* [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access in find_epilogue_using_linetable
@ 2024-04-09 9:27 Tom de Vries
2024-04-09 9:27 ` [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function " Tom de Vries
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Tom de Vries @ 2024-04-09 9:27 UTC (permalink / raw)
To: gdb-patches
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
An out of bounds array access in find_epilogue_using_linetable causes random
test failures like these:
FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $fba_value == $fn_fba
FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: check frame-id matches
FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: bt 2
FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: up
FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $sp_value == $::main_sp
FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $fba_value == $::main_fba
FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: [string equal $fid $::main_fid]
Here the read happens below the first element of the line
table, and the test failure depends on the value that is
read from there.
It also happens that std::lower_bound returns a pointer exactly at the upper
bound of the line table, also here the read value is undefined, that happens
in this test:
FAIL: gdb.dwarf2/dw2-epilogue-begin.exp: confirm watchpoint doesn't trigger
Fixes: 528b729be1a2 ("gdb/dwarf2: Add support for DW_LNS_set_epilogue_begin in line-table")
Co-Authored-By: Tom de Vries <tdevries@suse.de>
PR symtab/31268
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31268
---
gdb/symtab.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 84 insertions(+), 10 deletions(-)
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 86603dfebc3..e032178aaa6 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -4156,6 +4156,9 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
if (!find_pc_partial_function (func_addr, nullptr, &start_pc, &end_pc))
return {};
+ /* While the standard allows for multiple points marked with epilogue_begin
+ in the same function, for performance reasons, this function will only
+ find the last address that sets this flag for a given block. */
const struct symtab_and_line sal = find_pc_line (start_pc, 0);
if (sal.symtab != nullptr && sal.symtab->language () != language_asm)
{
@@ -4166,24 +4169,95 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
= unrelocated_addr (end_pc - objfile->text_section_offset ());
const linetable *linetable = sal.symtab->linetable ();
- /* This should find the last linetable entry of the current function.
- It is probably where the epilogue begins, but since the DWARF 5
- spec doesn't guarantee it, we iterate backwards through the function
- until we either find it or are sure that it doesn't exist. */
+ if (linetable == nullptr || linetable->nitems == 0)
+ {
+ /* Empty line table. */
+ return {};
+ }
+
+ /* Find the first linetable entry after the current function. Note that
+ this also may be an end_sequence entry. */
auto it = std::lower_bound
(linetable->item, linetable->item + linetable->nitems, unrel_end,
[] (const linetable_entry <e, unrelocated_addr pc)
{
return lte.unrelocated_pc () < pc;
});
+ if (it == linetable->item + linetable->nitems)
+ {
+ /* We couldn't find either:
+ - a linetable entry starting the function after the current
+ function, or
+ - an end_sequence entry that terminates the current function
+ at unrel_end.
+
+ This can happen when the linetable doesn't describe the full
+ extent of the function. This can be triggered with:
+ - compiler-generated debug info, in the cornercase that the pc
+ with which we call find_pc_line resides in a different file
+ than unrel_end, or
+ - invalid dwarf assembly debug info.
+ In the former case, there's no point in iterating further, simply
+ return "not found". In the latter case, there's no current
+ incentive to attempt to support this, so handle this
+ conservatively and do the same. */
+ return {};
+ }
- while (it->unrelocated_pc () >= unrel_start)
- {
- if (it->epilogue_begin)
- return {it->pc (objfile)};
- it --;
- }
+ if (unrel_end < it->unrelocated_pc ())
+ {
+ /* We found a line entry that starts past the end of the
+ function. This can happen if the previous entry straddles
+ two functions, which shouldn't happen with compiler-generated
+ debug info. Handle the corner case conservatively. */
+ return {};
+ }
+ gdb_assert (unrel_end == it->unrelocated_pc ());
+
+ /* Move to the last linetable entry of the current function. */
+ if (it == &linetable->item[0])
+ {
+ /* Doing it-- would introduce undefined behaviour, avoid it by
+ explicitly handling this case. */
+ return {};
+ }
+ it--;
+ if (it->unrelocated_pc () < unrel_start)
+ {
+ /* Not in the current function. */
+ return {};
+ }
+ gdb_assert (it->unrelocated_pc () < unrel_end);
+
+ /* We're at the the last linetable entry of the current function. This
+ is probably where the epilogue begins, but since the DWARF 5 spec
+ doesn't guarantee it, we iterate backwards through the current
+ function until we either find the epilogue beginning, or are sure
+ that it doesn't exist. */
+ for (; it >= &linetable->item[0]; it--)
+ {
+ if (it->unrelocated_pc () < unrel_start)
+ {
+ /* No longer in the current function. */
+ break;
+ }
+
+ if (it->epilogue_begin)
+ {
+ /* Found the beginning of the epilogue. */
+ return {it->pc (objfile)};
+ }
+
+ if (it == &linetable->item[0])
+ {
+ /* No more entries in the current function.
+ Doing it-- would introduce undefined behaviour, avoid it by
+ explicitly handling this case. */
+ break;
+ }
+ }
}
+
return {};
}
base-commit: 9132c8152b899a1683bc886f8ba76bedadb48aa1
--
2.35.3
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function in find_epilogue_using_linetable
2024-04-09 9:27 [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access in find_epilogue_using_linetable Tom de Vries
@ 2024-04-09 9:27 ` Tom de Vries
2024-04-10 7:28 ` Bernd Edlinger
2024-04-22 13:39 ` Andrew Burgess
2024-04-11 13:59 ` [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access " Bernd Edlinger
2024-04-22 13:22 ` Andrew Burgess
2 siblings, 2 replies; 6+ messages in thread
From: Tom de Vries @ 2024-04-09 9:27 UTC (permalink / raw)
To: gdb-patches
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Consider the following test-case:
...
$ cat hello.c
int main()
{
printf("hello ");
#include "world.inc"
$ cat world.inc
printf("world\n");
return 0;
}
$ gcc -g hello.c
...
The line table for the compilation unit, consisting just of
function main, is translated into these two gdb line tables, one for hello.c
and one for world.inc:
...
compunit_symtab: hello.c
symtab: hello.c
INDEX LINE REL-ADDRESS UNREL-ADDRESS IS-STMT PROLOGUE-END EPILOGUE-BEGIN
0 3 0x400557 0x400557 Y
1 4 0x40055b 0x40055b Y
2 END 0x40056a 0x40056a Y
compunit_symtab: hello.c
symtab: world.inc
INDEX LINE REL-ADDRESS UNREL-ADDRESS IS-STMT PROLOGUE-END EPILOGUE-BEGIN
0 1 0x40056a 0x40056a Y
1 2 0x400574 0x400574 Y
2 3 0x400579 0x400579 Y
3 END 0x40057b 0x40057b Y
...
The epilogue of main starts at 0x400579:
...
400579: 5d pop %rbp
40057a: c3 ret
...
Now, say we have an epilogue_begin marker in the line table at 0x400579.
We won't find it using find_epilogue_using_linetable, because it does:
...
const struct symtab_and_line sal = find_pc_line (start_pc, 0);
...
which gets us the line table for hello.c.
Fix this by using "find_pc_line (end_pc - 1, 0)" instead.
Tested on x86_64-linux.
Co-Authored-By: Tom de Vries <tdevries@suse.de>
PR symtab/31622
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31622
---
gdb/symtab.c | 11 +-
.../gdb.dwarf2/dw2-epilogue-begin-2.exp | 20 ++
.../gdb.dwarf2/dw2-epilogue-begin.c.inc | 51 +++++
.../gdb.dwarf2/dw2-epilogue-begin.exp | 157 +-------------
.../gdb.dwarf2/dw2-epilogue-begin.exp.tcl | 199 ++++++++++++++++++
gdb/testsuite/lib/dwarf.exp | 5 +-
6 files changed, 284 insertions(+), 159 deletions(-)
create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
diff --git a/gdb/symtab.c b/gdb/symtab.c
index e032178aaa6..034f71226b6 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -4158,8 +4158,15 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
/* While the standard allows for multiple points marked with epilogue_begin
in the same function, for performance reasons, this function will only
- find the last address that sets this flag for a given block. */
- const struct symtab_and_line sal = find_pc_line (start_pc, 0);
+ find the last address that sets this flag for a given block.
+
+ The lines of a function can be described by several line tables in case
+ there are different files involved. There's a corner case where a
+ function epilogue is in a different file than a function start, and using
+ start_pc as argument to find_pc_line will mean we won't find the
+ epilogue. Instead, use "end_pc - 1" to maximize our changes of picking
+ the line table containing an epilogue. */
+ const struct symtab_and_line sal = find_pc_line (end_pc - 1, 0);
if (sal.symtab != nullptr && sal.symtab->language () != language_asm)
{
struct objfile *objfile = sal.symtab->compunit ()->objfile ();
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
new file mode 100644
index 00000000000..6302ef1ad05
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
@@ -0,0 +1,20 @@
+# Copyright 2022-2024 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+standard_testfile dw2-epilogue-begin.c dw2-epilogue-begin.S
+
+set version 2
+
+source $srcdir/$subdir/dw2-epilogue-begin.exp.tcl
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
new file mode 100644
index 00000000000..4ff445cf37d
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
@@ -0,0 +1,51 @@
+/* Copyright 2023-2024 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+
+void
+__attribute__((used))
+trivial (void)
+{
+ asm ("trivial_label: .global trivial_label"); /* trivial function */
+}
+
+char global;
+
+void
+watch (void)
+{ /* watch start */
+ asm ("watch_label: .global watch_label");
+ asm ("mov $0x0, %rax");
+ int local = 0; /* watch prologue */
+
+ asm ("watch_start: .global watch_start");
+ asm ("mov $0x1, %rax");
+ local = 1; /* watch assign */
+ asm ("watch_reassign: .global watch_reassign");
+ asm ("mov $0x2, %rax");
+ local = 2; /* watch reassign */
+ asm ("watch_end: .global watch_end"); /* watch end */
+}
+
+int
+main (void)
+{ /* main prologue */
+ asm ("main_label: .global main_label");
+ global = 0;
+ asm ("main_fun_call: .global main_fun_call");
+ watch (); /* main function call */
+ asm ("main_epilogue: .global main_epilogue");
+ global = 10;
+ return 0; /* main end */
+}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
index f646e23da62..9b9d6c71de4 100644
--- a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
+++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
@@ -13,161 +13,8 @@
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
-# Check that GDB can honor the epilogue_begin flag the compiler can place
-# in the line-table data.
-# We test 2 things: 1. that a software watchpoint triggered in an epilogue
-# is correctly ignored
-# 2. that GDB can mark the same line as both prologue and epilogue
-
-load_lib dwarf.exp
-
-# This test can only be run on targets which support DWARF-2 and use gas.
-require dwarf2_support
-# restricted to x86 to make it simpler to follow a variable
-require is_x86_64_m64_target
-
standard_testfile .c .S
-set trivial_line [gdb_get_line_number "trivial function"]
-set main_prologue [gdb_get_line_number "main prologue"]
-set main_epilogue [gdb_get_line_number "main end"]
-set watch_start_line [gdb_get_line_number "watch start"]
-
-set asm_file [standard_output_file $srcfile2]
-
-# The producer will be set to clang because at the time of writing
-# we only care about epilogues if the producer is clang. When the
-# producer is GCC, variables use CFA locations, so watchpoints can
-# continue working even on epilogues.
-Dwarf::assemble $asm_file {
- global srcdir subdir srcfile srcfile2
- global trivial_line main_prologue main_epilogue watch_start_line
- declare_labels lines_label
-
- get_func_info main
- get_func_info trivial
- get_func_info watch
-
- cu {} {
- compile_unit {
- {language @DW_LANG_C}
- {name dw2-prologue-end.c}
- {stmt_list ${lines_label} DW_FORM_sec_offset}
- {producer "clang version 17.0.1"}
- } {
- declare_labels char_label
-
- char_label: base_type {
- {name char}
- {encoding @DW_ATE_signed}
- {byte_size 1 DW_FORM_sdata}
- }
-
- subprogram {
- {external 1 flag}
- {name trivial}
- {low_pc $trivial_start addr}
- {high_pc "$trivial_start + $trivial_len" addr}
- }
- subprogram {
- {external 1 flag}
- {name watch}
- {low_pc $watch_start addr}
- {high_pc "$watch_start + $watch_len" addr}
- } {
- DW_TAG_variable {
- {name local}
- {type :$char_label}
- {DW_AT_location {DW_OP_reg0} SPECIAL_expr}
- }
- }
- subprogram {
- {external 1 flag}
- {name main}
- {low_pc $main_start addr}
- {high_pc "$main_start + $main_len" addr}
- }
- }
- }
-
- lines {version 5} lines_label {
- set diridx [include_dir "${srcdir}/${subdir}"]
- file_name "$srcfile" $diridx
-
- program {
- DW_LNS_set_file $diridx
- DW_LNE_set_address $trivial_start
- line $trivial_line
- DW_LNS_set_prologue_end
- DW_LNS_set_epilogue_begin
- DW_LNS_copy
-
- DW_LNE_set_address watch
- line $watch_start_line
- DW_LNS_copy
-
- DW_LNE_set_address watch_start
- line [gdb_get_line_number "watch assign"]
- DW_LNS_set_prologue_end
- DW_LNS_copy
-
- DW_LNE_set_address watch_reassign
- line [gdb_get_line_number "watch reassign"]
- DW_LNS_set_epilogue_begin
- DW_LNS_copy
-
- DW_LNE_set_address watch_end
- line [gdb_get_line_number "watch end"]
- DW_LNS_copy
-
- DW_LNE_set_address $main_start
- line $main_prologue
- DW_LNS_set_prologue_end
- DW_LNS_copy
-
- DW_LNE_set_address main_fun_call
- line [gdb_get_line_number "main function call"]
- DW_LNS_copy
-
- DW_LNE_set_address main_epilogue
- line $main_epilogue
- DW_LNS_set_epilogue_begin
- DW_LNS_copy
-
- DW_LNE_end_sequence
- }
- }
-}
-
-if { [prepare_for_testing "failed to prepare" ${testfile} \
- [list $srcfile $asm_file] {nodebug}] } {
- return -1
-}
-
-if ![runto_main] {
- return -1
-}
-
-# Moving to the scope with a local variable.
-gdb_breakpoint $watch_start_line
-gdb_continue_to_breakpoint "continuing to function" ".*"
-gdb_test "next" "local = 2.*" "stepping to epilogue"
-
-# Forcing software watchpoints because hardware ones don't care if we
-# are in the epilogue or not.
-gdb_test_no_output "set can-use-hw-watchpoints 0"
-
-# Test that the software watchpoint will not trigger in this case
-gdb_test "watch local" "\[W|w\]atchpoint .: local" "set watchpoint"
-gdb_test "continue" ".*\[W|w\]atchpoint . deleted.*" \
- "confirm watchpoint doesn't trigger"
+set version 1
-# First we test that the trivial function has a line with both a prologue
-# and an epilogue. Do this by finding a line that has 3 Y columns
-set sep "\[ \t\]"
-set hex_number "0x\[0-9a-f\]+"
-gdb_test_multiple "maint info line-table" "test epilogue in linetable" -lbl {
- -re "\[0-9\]$sep+$trivial_line$sep+$hex_number$sep+$hex_number$sep+Y$sep+Y$sep+Y" {
- pass $gdb_test_name
- }
-}
+source $srcdir/$subdir/dw2-epilogue-begin.exp.tcl
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
new file mode 100644
index 00000000000..155916b92df
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
@@ -0,0 +1,199 @@
+# Copyright 2022-2024 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# Check that GDB can honor the epilogue_begin flag the compiler can place
+# in the line-table data.
+# We test 2 things: 1. that a software watchpoint triggered in an epilogue
+# is correctly ignored
+# 2. that GDB can mark the same line as both prologue and epilogue
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+require dwarf2_support
+# restricted to x86 to make it simpler to follow a variable
+require is_x86_64_m64_target
+
+set trivial_line [gdb_get_line_number "trivial function"]
+set main_prologue [gdb_get_line_number "main prologue"]
+set main_epilogue [gdb_get_line_number "main end"]
+set watch_start_line [gdb_get_line_number "watch start"]
+
+set asm_file [standard_output_file $srcfile2]
+
+# The producer will be set to clang because at the time of writing
+# we only care about epilogues if the producer is clang. When the
+# producer is GCC, variables use CFA locations, so watchpoints can
+# continue working even on epilogues.
+Dwarf::assemble $asm_file {
+ global srcdir subdir srcfile srcfile2
+ global trivial_line main_prologue main_epilogue watch_start_line
+ declare_labels lines_label
+
+ get_func_info main
+ get_func_info trivial
+ get_func_info watch
+
+ if { $::version == 1 } {
+ set switch_file {}
+ } elseif { $::version == 2 } {
+ set switch_file { set f $f2 }
+ } else {
+ error "Unhandled version: $::version"
+ }
+
+ cu {} {
+ compile_unit {
+ {language @DW_LANG_C}
+ {name dw2-prologue-end.c}
+ {stmt_list ${lines_label} DW_FORM_sec_offset}
+ {producer "clang version 17.0.1"}
+ } {
+ declare_labels char_label
+
+ char_label: base_type {
+ {name char}
+ {encoding @DW_ATE_signed}
+ {byte_size 1 DW_FORM_sdata}
+ }
+
+ subprogram {
+ {external 1 flag}
+ {name trivial}
+ {low_pc $trivial_start addr}
+ {high_pc "$trivial_start + $trivial_len" addr}
+ }
+ subprogram {
+ {external 1 flag}
+ {name watch}
+ {low_pc $watch_start addr}
+ {high_pc "$watch_start + $watch_len" addr}
+ } {
+ DW_TAG_variable {
+ {name local}
+ {type :$char_label}
+ {DW_AT_location {DW_OP_reg0} SPECIAL_expr}
+ }
+ }
+ subprogram {
+ {external 1 flag}
+ {name main}
+ {low_pc $main_start addr}
+ {high_pc "$main_start + $main_len" addr}
+ }
+ }
+ }
+
+ lines {version 5} lines_label {
+ set diridx [include_dir "${srcdir}/${subdir}"]
+ set f1 [file_name "$srcfile" $diridx]
+ set f2 [file_name "$srcfile.inc" $diridx]
+
+ set f $f1
+ program {
+ DW_LNS_set_file $f
+
+ DW_LNE_set_address $trivial_start
+ line $trivial_line
+ DW_LNS_set_prologue_end
+ DW_LNS_set_epilogue_begin
+ DW_LNS_copy
+
+ DW_LNE_set_address $trivial_end
+ DW_LNE_end_sequence
+
+
+ DW_LNS_set_file $f
+
+ DW_LNE_set_address $watch_start
+ line $watch_start_line
+ DW_LNS_copy
+
+ DW_LNE_set_address watch_start
+ line [gdb_get_line_number "watch assign"]
+ DW_LNS_set_prologue_end
+ DW_LNS_copy
+
+ eval $switch_file
+ DW_LNS_set_file $f
+
+ DW_LNE_set_address watch_reassign
+ line [gdb_get_line_number "watch reassign"]
+ DW_LNS_set_epilogue_begin
+ DW_LNS_copy
+
+ DW_LNE_set_address watch_end
+ line [gdb_get_line_number "watch end"]
+ DW_LNS_copy
+
+ DW_LNE_set_address $watch_end
+ DW_LNE_end_sequence
+
+
+ DW_LNS_set_file $f
+
+ DW_LNE_set_address $main_start
+ line $main_prologue
+ DW_LNS_set_prologue_end
+ DW_LNS_copy
+
+ DW_LNE_set_address main_fun_call
+ line [gdb_get_line_number "main function call"]
+ DW_LNS_copy
+
+ DW_LNE_set_address main_epilogue
+ line $main_epilogue
+ DW_LNS_set_epilogue_begin
+ DW_LNS_copy
+
+ DW_LNE_set_address $main_end
+ DW_LNE_end_sequence
+ }
+ }
+}
+
+if { [prepare_for_testing "failed to prepare" ${testfile} \
+ [list $srcfile $asm_file] {nodebug}] } {
+ return -1
+}
+
+if ![runto_main] {
+ return -1
+}
+
+# Moving to the scope with a local variable.
+
+gdb_breakpoint $srcfile:$watch_start_line
+gdb_continue_to_breakpoint "continuing to function" ".*"
+gdb_test "next" "local = 2.*" "stepping to epilogue"
+
+# Forcing software watchpoints because hardware ones don't care if we
+# are in the epilogue or not.
+gdb_test_no_output "set can-use-hw-watchpoints 0"
+
+# Test that the software watchpoint will not trigger in this case
+gdb_test "watch local" "\[W|w\]atchpoint .: local" "set watchpoint"
+gdb_test "continue" ".*\[W|w\]atchpoint . deleted.*" \
+ "confirm watchpoint doesn't trigger"
+
+# First we test that the trivial function has a line with both a prologue
+# and an epilogue. Do this by finding a line that has 3 Y columns
+set sep "\[ \t\]"
+set hex_number "0x\[0-9a-f\]+"
+gdb_test_multiple "maint info line-table" "test epilogue in linetable" -lbl {
+ -re "\[0-9\]$sep+$trivial_line$sep+$hex_number$sep+$hex_number$sep+Y$sep+Y$sep+Y" {
+ pass $gdb_test_name
+ }
+}
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index d085f835f07..adc3a18ee4f 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -2427,10 +2427,11 @@ namespace eval Dwarf {
variable _line_file_names
lappend _line_file_names $filename $diridx
+ set nr_filenames [expr [llength $_line_file_names] / 2]
if { $Dwarf::_line_unit_version >= 5 } {
- return [expr [llength $_line_file_names] - 1]
+ return [expr $nr_filenames - 1]
} else {
- return [llength $_line_file_names]
+ return $nr_filenames
}
}
--
2.35.3
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function in find_epilogue_using_linetable
2024-04-09 9:27 ` [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function " Tom de Vries
@ 2024-04-10 7:28 ` Bernd Edlinger
2024-04-22 13:39 ` Andrew Burgess
1 sibling, 0 replies; 6+ messages in thread
From: Bernd Edlinger @ 2024-04-10 7:28 UTC (permalink / raw)
To: Tom de Vries, gdb-patches
Hi Tom,
Nice, just one nit below:
On 4/9/24 11:27, Tom de Vries wrote:
> From: Bernd Edlinger <bernd.edlinger@hotmail.de>
>
> Consider the following test-case:
> ...
> $ cat hello.c
> int main()
> {
> printf("hello ");
> #include "world.inc"
> $ cat world.inc
> printf("world\n");
> return 0;
> }
> $ gcc -g hello.c
> ...
>
> The line table for the compilation unit, consisting just of
> function main, is translated into these two gdb line tables, one for hello.c
> and one for world.inc:
> ...
> compunit_symtab: hello.c
> symtab: hello.c
> INDEX LINE REL-ADDRESS UNREL-ADDRESS IS-STMT PROLOGUE-END EPILOGUE-BEGIN
> 0 3 0x400557 0x400557 Y
> 1 4 0x40055b 0x40055b Y
> 2 END 0x40056a 0x40056a Y
>
> compunit_symtab: hello.c
> symtab: world.inc
> INDEX LINE REL-ADDRESS UNREL-ADDRESS IS-STMT PROLOGUE-END EPILOGUE-BEGIN
> 0 1 0x40056a 0x40056a Y
> 1 2 0x400574 0x400574 Y
> 2 3 0x400579 0x400579 Y
> 3 END 0x40057b 0x40057b Y
> ...
>
> The epilogue of main starts at 0x400579:
> ...
> 400579: 5d pop %rbp
> 40057a: c3 ret
> ...
>
> Now, say we have an epilogue_begin marker in the line table at 0x400579.
>
> We won't find it using find_epilogue_using_linetable, because it does:
> ...
> const struct symtab_and_line sal = find_pc_line (start_pc, 0);
> ...
> which gets us the line table for hello.c.
>
> Fix this by using "find_pc_line (end_pc - 1, 0)" instead.
>
> Tested on x86_64-linux.
>
> Co-Authored-By: Tom de Vries <tdevries@suse.de>
>
> PR symtab/31622
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31622
> ---
> gdb/symtab.c | 11 +-
> .../gdb.dwarf2/dw2-epilogue-begin-2.exp | 20 ++
> .../gdb.dwarf2/dw2-epilogue-begin.c.inc | 51 +++++
> .../gdb.dwarf2/dw2-epilogue-begin.exp | 157 +-------------
> .../gdb.dwarf2/dw2-epilogue-begin.exp.tcl | 199 ++++++++++++++++++
> gdb/testsuite/lib/dwarf.exp | 5 +-
> 6 files changed, 284 insertions(+), 159 deletions(-)
> create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
> create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
> create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
>
> diff --git a/gdb/symtab.c b/gdb/symtab.c
> index e032178aaa6..034f71226b6 100644
> --- a/gdb/symtab.c
> +++ b/gdb/symtab.c
> @@ -4158,8 +4158,15 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
>
> /* While the standard allows for multiple points marked with epilogue_begin
> in the same function, for performance reasons, this function will only
> - find the last address that sets this flag for a given block. */
> - const struct symtab_and_line sal = find_pc_line (start_pc, 0);
> + find the last address that sets this flag for a given block.
> +
> + The lines of a function can be described by several line tables in case
> + there are different files involved. There's a corner case where a
> + function epilogue is in a different file than a function start, and using
> + start_pc as argument to find_pc_line will mean we won't find the
> + epilogue. Instead, use "end_pc - 1" to maximize our changes of picking
s/changes/chances/
> + the line table containing an epilogue. */
> + const struct symtab_and_line sal = find_pc_line (end_pc - 1, 0);
> if (sal.symtab != nullptr && sal.symtab->language () != language_asm)
> {
> struct objfile *objfile = sal.symtab->compunit ()->objfile ();
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
> new file mode 100644
> index 00000000000..6302ef1ad05
> --- /dev/null
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
> @@ -0,0 +1,20 @@
> +# Copyright 2022-2024 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program. If not, see <http://www.gnu.org/licenses/>.
> +
> +standard_testfile dw2-epilogue-begin.c dw2-epilogue-begin.S
> +
> +set version 2
> +
> +source $srcdir/$subdir/dw2-epilogue-begin.exp.tcl
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
> new file mode 100644
> index 00000000000..4ff445cf37d
> --- /dev/null
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
> @@ -0,0 +1,51 @@
> +/* Copyright 2023-2024 Free Software Foundation, Inc.
> +
> + This program is free software; you can redistribute it and/or modify
> + it under the terms of the GNU General Public License as published by
> + the Free Software Foundation; either version 3 of the License, or
> + (at your option) any later version.
> +
> + This program is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + GNU General Public License for more details.
> +
> + You should have received a copy of the GNU General Public License
> + along with this program. If not, see <http://www.gnu.org/licenses/>. */
> +
> +void
> +__attribute__((used))
> +trivial (void)
> +{
> + asm ("trivial_label: .global trivial_label"); /* trivial function */
> +}
> +
> +char global;
> +
> +void
> +watch (void)
> +{ /* watch start */
> + asm ("watch_label: .global watch_label");
> + asm ("mov $0x0, %rax");
> + int local = 0; /* watch prologue */
> +
> + asm ("watch_start: .global watch_start");
> + asm ("mov $0x1, %rax");
> + local = 1; /* watch assign */
> + asm ("watch_reassign: .global watch_reassign");
> + asm ("mov $0x2, %rax");
> + local = 2; /* watch reassign */
> + asm ("watch_end: .global watch_end"); /* watch end */
> +}
> +
> +int
> +main (void)
> +{ /* main prologue */
> + asm ("main_label: .global main_label");
> + global = 0;
> + asm ("main_fun_call: .global main_fun_call");
> + watch (); /* main function call */
> + asm ("main_epilogue: .global main_epilogue");
> + global = 10;
> + return 0; /* main end */
> +}
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
> index f646e23da62..9b9d6c71de4 100644
> --- a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
> @@ -13,161 +13,8 @@
> # You should have received a copy of the GNU General Public License
> # along with this program. If not, see <http://www.gnu.org/licenses/>.
>
> -# Check that GDB can honor the epilogue_begin flag the compiler can place
> -# in the line-table data.
> -# We test 2 things: 1. that a software watchpoint triggered in an epilogue
> -# is correctly ignored
> -# 2. that GDB can mark the same line as both prologue and epilogue
> -
> -load_lib dwarf.exp
> -
> -# This test can only be run on targets which support DWARF-2 and use gas.
> -require dwarf2_support
> -# restricted to x86 to make it simpler to follow a variable
> -require is_x86_64_m64_target
> -
> standard_testfile .c .S
>
> -set trivial_line [gdb_get_line_number "trivial function"]
> -set main_prologue [gdb_get_line_number "main prologue"]
> -set main_epilogue [gdb_get_line_number "main end"]
> -set watch_start_line [gdb_get_line_number "watch start"]
> -
> -set asm_file [standard_output_file $srcfile2]
> -
> -# The producer will be set to clang because at the time of writing
> -# we only care about epilogues if the producer is clang. When the
> -# producer is GCC, variables use CFA locations, so watchpoints can
> -# continue working even on epilogues.
> -Dwarf::assemble $asm_file {
> - global srcdir subdir srcfile srcfile2
> - global trivial_line main_prologue main_epilogue watch_start_line
> - declare_labels lines_label
> -
> - get_func_info main
> - get_func_info trivial
> - get_func_info watch
> -
> - cu {} {
> - compile_unit {
> - {language @DW_LANG_C}
> - {name dw2-prologue-end.c}
> - {stmt_list ${lines_label} DW_FORM_sec_offset}
> - {producer "clang version 17.0.1"}
> - } {
> - declare_labels char_label
> -
> - char_label: base_type {
> - {name char}
> - {encoding @DW_ATE_signed}
> - {byte_size 1 DW_FORM_sdata}
> - }
> -
> - subprogram {
> - {external 1 flag}
> - {name trivial}
> - {low_pc $trivial_start addr}
> - {high_pc "$trivial_start + $trivial_len" addr}
> - }
> - subprogram {
> - {external 1 flag}
> - {name watch}
> - {low_pc $watch_start addr}
> - {high_pc "$watch_start + $watch_len" addr}
> - } {
> - DW_TAG_variable {
> - {name local}
> - {type :$char_label}
> - {DW_AT_location {DW_OP_reg0} SPECIAL_expr}
> - }
> - }
> - subprogram {
> - {external 1 flag}
> - {name main}
> - {low_pc $main_start addr}
> - {high_pc "$main_start + $main_len" addr}
> - }
> - }
> - }
> -
> - lines {version 5} lines_label {
> - set diridx [include_dir "${srcdir}/${subdir}"]
> - file_name "$srcfile" $diridx
> -
> - program {
> - DW_LNS_set_file $diridx
> - DW_LNE_set_address $trivial_start
> - line $trivial_line
> - DW_LNS_set_prologue_end
> - DW_LNS_set_epilogue_begin
> - DW_LNS_copy
> -
> - DW_LNE_set_address watch
> - line $watch_start_line
> - DW_LNS_copy
> -
> - DW_LNE_set_address watch_start
> - line [gdb_get_line_number "watch assign"]
> - DW_LNS_set_prologue_end
> - DW_LNS_copy
> -
> - DW_LNE_set_address watch_reassign
> - line [gdb_get_line_number "watch reassign"]
> - DW_LNS_set_epilogue_begin
> - DW_LNS_copy
> -
> - DW_LNE_set_address watch_end
> - line [gdb_get_line_number "watch end"]
> - DW_LNS_copy
> -
> - DW_LNE_set_address $main_start
> - line $main_prologue
> - DW_LNS_set_prologue_end
> - DW_LNS_copy
> -
> - DW_LNE_set_address main_fun_call
> - line [gdb_get_line_number "main function call"]
> - DW_LNS_copy
> -
> - DW_LNE_set_address main_epilogue
> - line $main_epilogue
> - DW_LNS_set_epilogue_begin
> - DW_LNS_copy
> -
> - DW_LNE_end_sequence
> - }
> - }
> -}
> -
> -if { [prepare_for_testing "failed to prepare" ${testfile} \
> - [list $srcfile $asm_file] {nodebug}] } {
> - return -1
> -}
> -
> -if ![runto_main] {
> - return -1
> -}
> -
> -# Moving to the scope with a local variable.
> -gdb_breakpoint $watch_start_line
> -gdb_continue_to_breakpoint "continuing to function" ".*"
> -gdb_test "next" "local = 2.*" "stepping to epilogue"
> -
> -# Forcing software watchpoints because hardware ones don't care if we
> -# are in the epilogue or not.
> -gdb_test_no_output "set can-use-hw-watchpoints 0"
> -
> -# Test that the software watchpoint will not trigger in this case
> -gdb_test "watch local" "\[W|w\]atchpoint .: local" "set watchpoint"
> -gdb_test "continue" ".*\[W|w\]atchpoint . deleted.*" \
> - "confirm watchpoint doesn't trigger"
> +set version 1
>
> -# First we test that the trivial function has a line with both a prologue
> -# and an epilogue. Do this by finding a line that has 3 Y columns
> -set sep "\[ \t\]"
> -set hex_number "0x\[0-9a-f\]+"
> -gdb_test_multiple "maint info line-table" "test epilogue in linetable" -lbl {
> - -re "\[0-9\]$sep+$trivial_line$sep+$hex_number$sep+$hex_number$sep+Y$sep+Y$sep+Y" {
> - pass $gdb_test_name
> - }
> -}
> +source $srcdir/$subdir/dw2-epilogue-begin.exp.tcl
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
> new file mode 100644
> index 00000000000..155916b92df
> --- /dev/null
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
> @@ -0,0 +1,199 @@
> +# Copyright 2022-2024 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program. If not, see <http://www.gnu.org/licenses/>.
> +
> +# Check that GDB can honor the epilogue_begin flag the compiler can place
> +# in the line-table data.
> +# We test 2 things: 1. that a software watchpoint triggered in an epilogue
> +# is correctly ignored
> +# 2. that GDB can mark the same line as both prologue and epilogue
> +
> +load_lib dwarf.exp
> +
> +# This test can only be run on targets which support DWARF-2 and use gas.
> +require dwarf2_support
> +# restricted to x86 to make it simpler to follow a variable
> +require is_x86_64_m64_target
> +
> +set trivial_line [gdb_get_line_number "trivial function"]
> +set main_prologue [gdb_get_line_number "main prologue"]
> +set main_epilogue [gdb_get_line_number "main end"]
> +set watch_start_line [gdb_get_line_number "watch start"]
> +
> +set asm_file [standard_output_file $srcfile2]
> +
> +# The producer will be set to clang because at the time of writing
> +# we only care about epilogues if the producer is clang. When the
> +# producer is GCC, variables use CFA locations, so watchpoints can
> +# continue working even on epilogues.
> +Dwarf::assemble $asm_file {
> + global srcdir subdir srcfile srcfile2
> + global trivial_line main_prologue main_epilogue watch_start_line
> + declare_labels lines_label
> +
> + get_func_info main
> + get_func_info trivial
> + get_func_info watch
> +
> + if { $::version == 1 } {
> + set switch_file {}
> + } elseif { $::version == 2 } {
> + set switch_file { set f $f2 }
> + } else {
> + error "Unhandled version: $::version"
> + }
> +
> + cu {} {
> + compile_unit {
> + {language @DW_LANG_C}
> + {name dw2-prologue-end.c}
> + {stmt_list ${lines_label} DW_FORM_sec_offset}
> + {producer "clang version 17.0.1"}
> + } {
> + declare_labels char_label
> +
> + char_label: base_type {
> + {name char}
> + {encoding @DW_ATE_signed}
> + {byte_size 1 DW_FORM_sdata}
> + }
> +
> + subprogram {
> + {external 1 flag}
> + {name trivial}
> + {low_pc $trivial_start addr}
> + {high_pc "$trivial_start + $trivial_len" addr}
> + }
> + subprogram {
> + {external 1 flag}
> + {name watch}
> + {low_pc $watch_start addr}
> + {high_pc "$watch_start + $watch_len" addr}
> + } {
> + DW_TAG_variable {
> + {name local}
> + {type :$char_label}
> + {DW_AT_location {DW_OP_reg0} SPECIAL_expr}
> + }
> + }
> + subprogram {
> + {external 1 flag}
> + {name main}
> + {low_pc $main_start addr}
> + {high_pc "$main_start + $main_len" addr}
> + }
> + }
> + }
> +
> + lines {version 5} lines_label {
> + set diridx [include_dir "${srcdir}/${subdir}"]
> + set f1 [file_name "$srcfile" $diridx]
> + set f2 [file_name "$srcfile.inc" $diridx]
> +
> + set f $f1
> + program {
> + DW_LNS_set_file $f
> +
> + DW_LNE_set_address $trivial_start
> + line $trivial_line
> + DW_LNS_set_prologue_end
> + DW_LNS_set_epilogue_begin
> + DW_LNS_copy
> +
> + DW_LNE_set_address $trivial_end
> + DW_LNE_end_sequence
> +
> +
> + DW_LNS_set_file $f
> +
> + DW_LNE_set_address $watch_start
> + line $watch_start_line
> + DW_LNS_copy
> +
> + DW_LNE_set_address watch_start
> + line [gdb_get_line_number "watch assign"]
> + DW_LNS_set_prologue_end
> + DW_LNS_copy
> +
> + eval $switch_file
> + DW_LNS_set_file $f
> +
> + DW_LNE_set_address watch_reassign
> + line [gdb_get_line_number "watch reassign"]
> + DW_LNS_set_epilogue_begin
> + DW_LNS_copy
> +
> + DW_LNE_set_address watch_end
> + line [gdb_get_line_number "watch end"]
> + DW_LNS_copy
> +
> + DW_LNE_set_address $watch_end
> + DW_LNE_end_sequence
> +
> +
> + DW_LNS_set_file $f
> +
> + DW_LNE_set_address $main_start
> + line $main_prologue
> + DW_LNS_set_prologue_end
> + DW_LNS_copy
> +
> + DW_LNE_set_address main_fun_call
> + line [gdb_get_line_number "main function call"]
> + DW_LNS_copy
> +
> + DW_LNE_set_address main_epilogue
> + line $main_epilogue
> + DW_LNS_set_epilogue_begin
> + DW_LNS_copy
> +
> + DW_LNE_set_address $main_end
> + DW_LNE_end_sequence
> + }
> + }
> +}
> +
> +if { [prepare_for_testing "failed to prepare" ${testfile} \
> + [list $srcfile $asm_file] {nodebug}] } {
> + return -1
> +}
> +
> +if ![runto_main] {
> + return -1
> +}
> +
> +# Moving to the scope with a local variable.
> +
> +gdb_breakpoint $srcfile:$watch_start_line
> +gdb_continue_to_breakpoint "continuing to function" ".*"
> +gdb_test "next" "local = 2.*" "stepping to epilogue"
> +
> +# Forcing software watchpoints because hardware ones don't care if we
> +# are in the epilogue or not.
> +gdb_test_no_output "set can-use-hw-watchpoints 0"
> +
> +# Test that the software watchpoint will not trigger in this case
> +gdb_test "watch local" "\[W|w\]atchpoint .: local" "set watchpoint"
> +gdb_test "continue" ".*\[W|w\]atchpoint . deleted.*" \
> + "confirm watchpoint doesn't trigger"
> +
> +# First we test that the trivial function has a line with both a prologue
> +# and an epilogue. Do this by finding a line that has 3 Y columns
> +set sep "\[ \t\]"
> +set hex_number "0x\[0-9a-f\]+"
> +gdb_test_multiple "maint info line-table" "test epilogue in linetable" -lbl {
> + -re "\[0-9\]$sep+$trivial_line$sep+$hex_number$sep+$hex_number$sep+Y$sep+Y$sep+Y" {
> + pass $gdb_test_name
> + }
> +}
> diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
> index d085f835f07..adc3a18ee4f 100644
> --- a/gdb/testsuite/lib/dwarf.exp
> +++ b/gdb/testsuite/lib/dwarf.exp
> @@ -2427,10 +2427,11 @@ namespace eval Dwarf {
> variable _line_file_names
> lappend _line_file_names $filename $diridx
>
> + set nr_filenames [expr [llength $_line_file_names] / 2]
> if { $Dwarf::_line_unit_version >= 5 } {
> - return [expr [llength $_line_file_names] - 1]
> + return [expr $nr_filenames - 1]
> } else {
> - return [llength $_line_file_names]
> + return $nr_filenames
> }
> }
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access in find_epilogue_using_linetable
2024-04-09 9:27 [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access in find_epilogue_using_linetable Tom de Vries
2024-04-09 9:27 ` [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function " Tom de Vries
@ 2024-04-11 13:59 ` Bernd Edlinger
2024-04-22 13:22 ` Andrew Burgess
2 siblings, 0 replies; 6+ messages in thread
From: Bernd Edlinger @ 2024-04-11 13:59 UTC (permalink / raw)
To: Tom de Vries, gdb-patches
On 4/9/24 11:27, Tom de Vries wrote:
> From: Bernd Edlinger <bernd.edlinger@hotmail.de>
>
> An out of bounds array access in find_epilogue_using_linetable causes random
> test failures like these:
>
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $fba_value == $fn_fba
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: check frame-id matches
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: bt 2
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: up
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $sp_value == $::main_sp
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $fba_value == $::main_fba
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: [string equal $fid $::main_fid]
>
> Here the read happens below the first element of the line
> table, and the test failure depends on the value that is
> read from there.
>
> It also happens that std::lower_bound returns a pointer exactly at the upper
> bound of the line table, also here the read value is undefined, that happens
> in this test:
>
> FAIL: gdb.dwarf2/dw2-epilogue-begin.exp: confirm watchpoint doesn't trigger
>
> Fixes: 528b729be1a2 ("gdb/dwarf2: Add support for DW_LNS_set_epilogue_begin in line-table")
>
> Co-Authored-By: Tom de Vries <tdevries@suse.de>
>
> PR symtab/31268
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31268
> ---
> gdb/symtab.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 84 insertions(+), 10 deletions(-)
>
> diff --git a/gdb/symtab.c b/gdb/symtab.c
> index 86603dfebc3..e032178aaa6 100644
> --- a/gdb/symtab.c
> +++ b/gdb/symtab.c
> @@ -4156,6 +4156,9 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
> if (!find_pc_partial_function (func_addr, nullptr, &start_pc, &end_pc))
> return {};
>
> + /* While the standard allows for multiple points marked with epilogue_begin
> + in the same function, for performance reasons, this function will only
> + find the last address that sets this flag for a given block. */
> const struct symtab_and_line sal = find_pc_line (start_pc, 0);
> if (sal.symtab != nullptr && sal.symtab->language () != language_asm)
> {
> @@ -4166,24 +4169,95 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
> = unrelocated_addr (end_pc - objfile->text_section_offset ());
>
> const linetable *linetable = sal.symtab->linetable ();
> - /* This should find the last linetable entry of the current function.
> - It is probably where the epilogue begins, but since the DWARF 5
> - spec doesn't guarantee it, we iterate backwards through the function
> - until we either find it or are sure that it doesn't exist. */
> + if (linetable == nullptr || linetable->nitems == 0)
> + {
> + /* Empty line table. */
> + return {};
> + }
> +
> + /* Find the first linetable entry after the current function. Note that
> + this also may be an end_sequence entry. */
> auto it = std::lower_bound
> (linetable->item, linetable->item + linetable->nitems, unrel_end,
> [] (const linetable_entry <e, unrelocated_addr pc)
> {
> return lte.unrelocated_pc () < pc;
> });
> + if (it == linetable->item + linetable->nitems)
> + {
> + /* We couldn't find either:
> + - a linetable entry starting the function after the current
> + function, or
> + - an end_sequence entry that terminates the current function
> + at unrel_end.
> +
> + This can happen when the linetable doesn't describe the full
> + extent of the function. This can be triggered with:
> + - compiler-generated debug info, in the cornercase that the pc
> + with which we call find_pc_line resides in a different file
> + than unrel_end, or
> + - invalid dwarf assembly debug info.
> + In the former case, there's no point in iterating further, simply
> + return "not found". In the latter case, there's no current
> + incentive to attempt to support this, so handle this
> + conservatively and do the same. */
> + return {};
> + }
>
> - while (it->unrelocated_pc () >= unrel_start)
> - {
> - if (it->epilogue_begin)
> - return {it->pc (objfile)};
> - it --;
> - }
> + if (unrel_end < it->unrelocated_pc ())
> + {
> + /* We found a line entry that starts past the end of the
> + function. This can happen if the previous entry straddles
> + two functions, which shouldn't happen with compiler-generated
> + debug info. Handle the corner case conservatively. */
> + return {};
> + }
> + gdb_assert (unrel_end == it->unrelocated_pc ());
> +
> + /* Move to the last linetable entry of the current function. */
> + if (it == &linetable->item[0])
> + {
> + /* Doing it-- would introduce undefined behaviour, avoid it by
> + explicitly handling this case. */
> + return {};
> + }
> + it--;
> + if (it->unrelocated_pc () < unrel_start)
> + {
> + /* Not in the current function. */
> + return {};
> + }
> + gdb_assert (it->unrelocated_pc () < unrel_end);
> +
> + /* We're at the the last linetable entry of the current function. This
> + is probably where the epilogue begins, but since the DWARF 5 spec
> + doesn't guarantee it, we iterate backwards through the current
> + function until we either find the epilogue beginning, or are sure
> + that it doesn't exist. */
> + for (; it >= &linetable->item[0]; it--)
> + {
> + if (it->unrelocated_pc () < unrel_start)
> + {
> + /* No longer in the current function. */
> + break;
> + }
> +
> + if (it->epilogue_begin)
> + {
> + /* Found the beginning of the epilogue. */
> + return {it->pc (objfile)};
> + }
> +
> + if (it == &linetable->item[0])
> + {
> + /* No more entries in the current function.
> + Doing it-- would introduce undefined behaviour, avoid it by
> + explicitly handling this case. */
> + break;
> + }
> + }
> }
> +
> return {};
> }
>
>
> base-commit: 9132c8152b899a1683bc886f8ba76bedadb48aa1
The patch is OK from my side.
Thanks
Bernd.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access in find_epilogue_using_linetable
2024-04-09 9:27 [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access in find_epilogue_using_linetable Tom de Vries
2024-04-09 9:27 ` [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function " Tom de Vries
2024-04-11 13:59 ` [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access " Bernd Edlinger
@ 2024-04-22 13:22 ` Andrew Burgess
2 siblings, 0 replies; 6+ messages in thread
From: Andrew Burgess @ 2024-04-22 13:22 UTC (permalink / raw)
To: Tom de Vries, gdb-patches
Tom de Vries <tdevries@suse.de> writes:
> From: Bernd Edlinger <bernd.edlinger@hotmail.de>
>
> An out of bounds array access in find_epilogue_using_linetable causes random
> test failures like these:
>
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $fba_value == $fn_fba
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: check frame-id matches
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: bt 2
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: up
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $sp_value == $::main_sp
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: $fba_value == $::main_fba
> FAIL: gdb.base/unwind-on-each-insn-amd64.exp: foo: instruction 6: [string equal $fid $::main_fid]
>
> Here the read happens below the first element of the line
> table, and the test failure depends on the value that is
> read from there.
>
> It also happens that std::lower_bound returns a pointer exactly at the upper
> bound of the line table, also here the read value is undefined, that happens
> in this test:
>
> FAIL: gdb.dwarf2/dw2-epilogue-begin.exp: confirm watchpoint doesn't trigger
>
> Fixes: 528b729be1a2 ("gdb/dwarf2: Add support for DW_LNS_set_epilogue_begin in line-table")
>
> Co-Authored-By: Tom de Vries <tdevries@suse.de>
LGTM.
Approved-By: Andrew Burgess <aburgess@redhat.com>
Thanks,
Andrew
>
> PR symtab/31268
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31268
> ---
> gdb/symtab.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 84 insertions(+), 10 deletions(-)
>
> diff --git a/gdb/symtab.c b/gdb/symtab.c
> index 86603dfebc3..e032178aaa6 100644
> --- a/gdb/symtab.c
> +++ b/gdb/symtab.c
> @@ -4156,6 +4156,9 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
> if (!find_pc_partial_function (func_addr, nullptr, &start_pc, &end_pc))
> return {};
>
> + /* While the standard allows for multiple points marked with epilogue_begin
> + in the same function, for performance reasons, this function will only
> + find the last address that sets this flag for a given block. */
> const struct symtab_and_line sal = find_pc_line (start_pc, 0);
> if (sal.symtab != nullptr && sal.symtab->language () != language_asm)
> {
> @@ -4166,24 +4169,95 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
> = unrelocated_addr (end_pc - objfile->text_section_offset ());
>
> const linetable *linetable = sal.symtab->linetable ();
> - /* This should find the last linetable entry of the current function.
> - It is probably where the epilogue begins, but since the DWARF 5
> - spec doesn't guarantee it, we iterate backwards through the function
> - until we either find it or are sure that it doesn't exist. */
> + if (linetable == nullptr || linetable->nitems == 0)
> + {
> + /* Empty line table. */
> + return {};
> + }
> +
> + /* Find the first linetable entry after the current function. Note that
> + this also may be an end_sequence entry. */
> auto it = std::lower_bound
> (linetable->item, linetable->item + linetable->nitems, unrel_end,
> [] (const linetable_entry <e, unrelocated_addr pc)
> {
> return lte.unrelocated_pc () < pc;
> });
> + if (it == linetable->item + linetable->nitems)
> + {
> + /* We couldn't find either:
> + - a linetable entry starting the function after the current
> + function, or
> + - an end_sequence entry that terminates the current function
> + at unrel_end.
> +
> + This can happen when the linetable doesn't describe the full
> + extent of the function. This can be triggered with:
> + - compiler-generated debug info, in the cornercase that the pc
> + with which we call find_pc_line resides in a different file
> + than unrel_end, or
> + - invalid dwarf assembly debug info.
> + In the former case, there's no point in iterating further, simply
> + return "not found". In the latter case, there's no current
> + incentive to attempt to support this, so handle this
> + conservatively and do the same. */
> + return {};
> + }
>
> - while (it->unrelocated_pc () >= unrel_start)
> - {
> - if (it->epilogue_begin)
> - return {it->pc (objfile)};
> - it --;
> - }
> + if (unrel_end < it->unrelocated_pc ())
> + {
> + /* We found a line entry that starts past the end of the
> + function. This can happen if the previous entry straddles
> + two functions, which shouldn't happen with compiler-generated
> + debug info. Handle the corner case conservatively. */
> + return {};
> + }
> + gdb_assert (unrel_end == it->unrelocated_pc ());
> +
> + /* Move to the last linetable entry of the current function. */
> + if (it == &linetable->item[0])
> + {
> + /* Doing it-- would introduce undefined behaviour, avoid it by
> + explicitly handling this case. */
> + return {};
> + }
> + it--;
> + if (it->unrelocated_pc () < unrel_start)
> + {
> + /* Not in the current function. */
> + return {};
> + }
> + gdb_assert (it->unrelocated_pc () < unrel_end);
> +
> + /* We're at the the last linetable entry of the current function. This
> + is probably where the epilogue begins, but since the DWARF 5 spec
> + doesn't guarantee it, we iterate backwards through the current
> + function until we either find the epilogue beginning, or are sure
> + that it doesn't exist. */
> + for (; it >= &linetable->item[0]; it--)
> + {
> + if (it->unrelocated_pc () < unrel_start)
> + {
> + /* No longer in the current function. */
> + break;
> + }
> +
> + if (it->epilogue_begin)
> + {
> + /* Found the beginning of the epilogue. */
> + return {it->pc (objfile)};
> + }
> +
> + if (it == &linetable->item[0])
> + {
> + /* No more entries in the current function.
> + Doing it-- would introduce undefined behaviour, avoid it by
> + explicitly handling this case. */
> + break;
> + }
> + }
> }
> +
> return {};
> }
>
>
> base-commit: 9132c8152b899a1683bc886f8ba76bedadb48aa1
> --
> 2.35.3
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function in find_epilogue_using_linetable
2024-04-09 9:27 ` [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function " Tom de Vries
2024-04-10 7:28 ` Bernd Edlinger
@ 2024-04-22 13:39 ` Andrew Burgess
1 sibling, 0 replies; 6+ messages in thread
From: Andrew Burgess @ 2024-04-22 13:39 UTC (permalink / raw)
To: Tom de Vries, gdb-patches
Tom de Vries <tdevries@suse.de> writes:
> From: Bernd Edlinger <bernd.edlinger@hotmail.de>
>
> Consider the following test-case:
> ...
> $ cat hello.c
> int main()
> {
> printf("hello ");
> #include "world.inc"
> $ cat world.inc
> printf("world\n");
> return 0;
> }
> $ gcc -g hello.c
> ...
>
> The line table for the compilation unit, consisting just of
> function main, is translated into these two gdb line tables, one for hello.c
> and one for world.inc:
> ...
> compunit_symtab: hello.c
> symtab: hello.c
> INDEX LINE REL-ADDRESS UNREL-ADDRESS IS-STMT PROLOGUE-END EPILOGUE-BEGIN
> 0 3 0x400557 0x400557 Y
> 1 4 0x40055b 0x40055b Y
> 2 END 0x40056a 0x40056a Y
>
> compunit_symtab: hello.c
> symtab: world.inc
> INDEX LINE REL-ADDRESS UNREL-ADDRESS IS-STMT PROLOGUE-END EPILOGUE-BEGIN
> 0 1 0x40056a 0x40056a Y
> 1 2 0x400574 0x400574 Y
> 2 3 0x400579 0x400579 Y
> 3 END 0x40057b 0x40057b Y
> ...
>
> The epilogue of main starts at 0x400579:
> ...
> 400579: 5d pop %rbp
> 40057a: c3 ret
> ...
>
> Now, say we have an epilogue_begin marker in the line table at 0x400579.
>
> We won't find it using find_epilogue_using_linetable, because it does:
> ...
> const struct symtab_and_line sal = find_pc_line (start_pc, 0);
> ...
> which gets us the line table for hello.c.
>
> Fix this by using "find_pc_line (end_pc - 1, 0)" instead.
>
> Tested on x86_64-linux.
>
> Co-Authored-By: Tom de Vries <tdevries@suse.de>
LGTM.
Approved-By: Andrew Burgess <aburgess@redhat.com>
Thanks,
Andrew
>
> PR symtab/31622
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31622
> ---
> gdb/symtab.c | 11 +-
> .../gdb.dwarf2/dw2-epilogue-begin-2.exp | 20 ++
> .../gdb.dwarf2/dw2-epilogue-begin.c.inc | 51 +++++
> .../gdb.dwarf2/dw2-epilogue-begin.exp | 157 +-------------
> .../gdb.dwarf2/dw2-epilogue-begin.exp.tcl | 199 ++++++++++++++++++
> gdb/testsuite/lib/dwarf.exp | 5 +-
> 6 files changed, 284 insertions(+), 159 deletions(-)
> create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
> create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
> create mode 100644 gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
>
> diff --git a/gdb/symtab.c b/gdb/symtab.c
> index e032178aaa6..034f71226b6 100644
> --- a/gdb/symtab.c
> +++ b/gdb/symtab.c
> @@ -4158,8 +4158,15 @@ find_epilogue_using_linetable (CORE_ADDR func_addr)
>
> /* While the standard allows for multiple points marked with epilogue_begin
> in the same function, for performance reasons, this function will only
> - find the last address that sets this flag for a given block. */
> - const struct symtab_and_line sal = find_pc_line (start_pc, 0);
> + find the last address that sets this flag for a given block.
> +
> + The lines of a function can be described by several line tables in case
> + there are different files involved. There's a corner case where a
> + function epilogue is in a different file than a function start, and using
> + start_pc as argument to find_pc_line will mean we won't find the
> + epilogue. Instead, use "end_pc - 1" to maximize our changes of picking
> + the line table containing an epilogue. */
> + const struct symtab_and_line sal = find_pc_line (end_pc - 1, 0);
> if (sal.symtab != nullptr && sal.symtab->language () != language_asm)
> {
> struct objfile *objfile = sal.symtab->compunit ()->objfile ();
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
> new file mode 100644
> index 00000000000..6302ef1ad05
> --- /dev/null
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin-2.exp
> @@ -0,0 +1,20 @@
> +# Copyright 2022-2024 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program. If not, see <http://www.gnu.org/licenses/>.
> +
> +standard_testfile dw2-epilogue-begin.c dw2-epilogue-begin.S
> +
> +set version 2
> +
> +source $srcdir/$subdir/dw2-epilogue-begin.exp.tcl
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
> new file mode 100644
> index 00000000000..4ff445cf37d
> --- /dev/null
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.c.inc
> @@ -0,0 +1,51 @@
> +/* Copyright 2023-2024 Free Software Foundation, Inc.
> +
> + This program is free software; you can redistribute it and/or modify
> + it under the terms of the GNU General Public License as published by
> + the Free Software Foundation; either version 3 of the License, or
> + (at your option) any later version.
> +
> + This program is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + GNU General Public License for more details.
> +
> + You should have received a copy of the GNU General Public License
> + along with this program. If not, see <http://www.gnu.org/licenses/>. */
> +
> +void
> +__attribute__((used))
> +trivial (void)
> +{
> + asm ("trivial_label: .global trivial_label"); /* trivial function */
> +}
> +
> +char global;
> +
> +void
> +watch (void)
> +{ /* watch start */
> + asm ("watch_label: .global watch_label");
> + asm ("mov $0x0, %rax");
> + int local = 0; /* watch prologue */
> +
> + asm ("watch_start: .global watch_start");
> + asm ("mov $0x1, %rax");
> + local = 1; /* watch assign */
> + asm ("watch_reassign: .global watch_reassign");
> + asm ("mov $0x2, %rax");
> + local = 2; /* watch reassign */
> + asm ("watch_end: .global watch_end"); /* watch end */
> +}
> +
> +int
> +main (void)
> +{ /* main prologue */
> + asm ("main_label: .global main_label");
> + global = 0;
> + asm ("main_fun_call: .global main_fun_call");
> + watch (); /* main function call */
> + asm ("main_epilogue: .global main_epilogue");
> + global = 10;
> + return 0; /* main end */
> +}
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
> index f646e23da62..9b9d6c71de4 100644
> --- a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp
> @@ -13,161 +13,8 @@
> # You should have received a copy of the GNU General Public License
> # along with this program. If not, see <http://www.gnu.org/licenses/>.
>
> -# Check that GDB can honor the epilogue_begin flag the compiler can place
> -# in the line-table data.
> -# We test 2 things: 1. that a software watchpoint triggered in an epilogue
> -# is correctly ignored
> -# 2. that GDB can mark the same line as both prologue and epilogue
> -
> -load_lib dwarf.exp
> -
> -# This test can only be run on targets which support DWARF-2 and use gas.
> -require dwarf2_support
> -# restricted to x86 to make it simpler to follow a variable
> -require is_x86_64_m64_target
> -
> standard_testfile .c .S
>
> -set trivial_line [gdb_get_line_number "trivial function"]
> -set main_prologue [gdb_get_line_number "main prologue"]
> -set main_epilogue [gdb_get_line_number "main end"]
> -set watch_start_line [gdb_get_line_number "watch start"]
> -
> -set asm_file [standard_output_file $srcfile2]
> -
> -# The producer will be set to clang because at the time of writing
> -# we only care about epilogues if the producer is clang. When the
> -# producer is GCC, variables use CFA locations, so watchpoints can
> -# continue working even on epilogues.
> -Dwarf::assemble $asm_file {
> - global srcdir subdir srcfile srcfile2
> - global trivial_line main_prologue main_epilogue watch_start_line
> - declare_labels lines_label
> -
> - get_func_info main
> - get_func_info trivial
> - get_func_info watch
> -
> - cu {} {
> - compile_unit {
> - {language @DW_LANG_C}
> - {name dw2-prologue-end.c}
> - {stmt_list ${lines_label} DW_FORM_sec_offset}
> - {producer "clang version 17.0.1"}
> - } {
> - declare_labels char_label
> -
> - char_label: base_type {
> - {name char}
> - {encoding @DW_ATE_signed}
> - {byte_size 1 DW_FORM_sdata}
> - }
> -
> - subprogram {
> - {external 1 flag}
> - {name trivial}
> - {low_pc $trivial_start addr}
> - {high_pc "$trivial_start + $trivial_len" addr}
> - }
> - subprogram {
> - {external 1 flag}
> - {name watch}
> - {low_pc $watch_start addr}
> - {high_pc "$watch_start + $watch_len" addr}
> - } {
> - DW_TAG_variable {
> - {name local}
> - {type :$char_label}
> - {DW_AT_location {DW_OP_reg0} SPECIAL_expr}
> - }
> - }
> - subprogram {
> - {external 1 flag}
> - {name main}
> - {low_pc $main_start addr}
> - {high_pc "$main_start + $main_len" addr}
> - }
> - }
> - }
> -
> - lines {version 5} lines_label {
> - set diridx [include_dir "${srcdir}/${subdir}"]
> - file_name "$srcfile" $diridx
> -
> - program {
> - DW_LNS_set_file $diridx
> - DW_LNE_set_address $trivial_start
> - line $trivial_line
> - DW_LNS_set_prologue_end
> - DW_LNS_set_epilogue_begin
> - DW_LNS_copy
> -
> - DW_LNE_set_address watch
> - line $watch_start_line
> - DW_LNS_copy
> -
> - DW_LNE_set_address watch_start
> - line [gdb_get_line_number "watch assign"]
> - DW_LNS_set_prologue_end
> - DW_LNS_copy
> -
> - DW_LNE_set_address watch_reassign
> - line [gdb_get_line_number "watch reassign"]
> - DW_LNS_set_epilogue_begin
> - DW_LNS_copy
> -
> - DW_LNE_set_address watch_end
> - line [gdb_get_line_number "watch end"]
> - DW_LNS_copy
> -
> - DW_LNE_set_address $main_start
> - line $main_prologue
> - DW_LNS_set_prologue_end
> - DW_LNS_copy
> -
> - DW_LNE_set_address main_fun_call
> - line [gdb_get_line_number "main function call"]
> - DW_LNS_copy
> -
> - DW_LNE_set_address main_epilogue
> - line $main_epilogue
> - DW_LNS_set_epilogue_begin
> - DW_LNS_copy
> -
> - DW_LNE_end_sequence
> - }
> - }
> -}
> -
> -if { [prepare_for_testing "failed to prepare" ${testfile} \
> - [list $srcfile $asm_file] {nodebug}] } {
> - return -1
> -}
> -
> -if ![runto_main] {
> - return -1
> -}
> -
> -# Moving to the scope with a local variable.
> -gdb_breakpoint $watch_start_line
> -gdb_continue_to_breakpoint "continuing to function" ".*"
> -gdb_test "next" "local = 2.*" "stepping to epilogue"
> -
> -# Forcing software watchpoints because hardware ones don't care if we
> -# are in the epilogue or not.
> -gdb_test_no_output "set can-use-hw-watchpoints 0"
> -
> -# Test that the software watchpoint will not trigger in this case
> -gdb_test "watch local" "\[W|w\]atchpoint .: local" "set watchpoint"
> -gdb_test "continue" ".*\[W|w\]atchpoint . deleted.*" \
> - "confirm watchpoint doesn't trigger"
> +set version 1
>
> -# First we test that the trivial function has a line with both a prologue
> -# and an epilogue. Do this by finding a line that has 3 Y columns
> -set sep "\[ \t\]"
> -set hex_number "0x\[0-9a-f\]+"
> -gdb_test_multiple "maint info line-table" "test epilogue in linetable" -lbl {
> - -re "\[0-9\]$sep+$trivial_line$sep+$hex_number$sep+$hex_number$sep+Y$sep+Y$sep+Y" {
> - pass $gdb_test_name
> - }
> -}
> +source $srcdir/$subdir/dw2-epilogue-begin.exp.tcl
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
> new file mode 100644
> index 00000000000..155916b92df
> --- /dev/null
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-epilogue-begin.exp.tcl
> @@ -0,0 +1,199 @@
> +# Copyright 2022-2024 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program. If not, see <http://www.gnu.org/licenses/>.
> +
> +# Check that GDB can honor the epilogue_begin flag the compiler can place
> +# in the line-table data.
> +# We test 2 things: 1. that a software watchpoint triggered in an epilogue
> +# is correctly ignored
> +# 2. that GDB can mark the same line as both prologue and epilogue
> +
> +load_lib dwarf.exp
> +
> +# This test can only be run on targets which support DWARF-2 and use gas.
> +require dwarf2_support
> +# restricted to x86 to make it simpler to follow a variable
> +require is_x86_64_m64_target
> +
> +set trivial_line [gdb_get_line_number "trivial function"]
> +set main_prologue [gdb_get_line_number "main prologue"]
> +set main_epilogue [gdb_get_line_number "main end"]
> +set watch_start_line [gdb_get_line_number "watch start"]
> +
> +set asm_file [standard_output_file $srcfile2]
> +
> +# The producer will be set to clang because at the time of writing
> +# we only care about epilogues if the producer is clang. When the
> +# producer is GCC, variables use CFA locations, so watchpoints can
> +# continue working even on epilogues.
> +Dwarf::assemble $asm_file {
> + global srcdir subdir srcfile srcfile2
> + global trivial_line main_prologue main_epilogue watch_start_line
> + declare_labels lines_label
> +
> + get_func_info main
> + get_func_info trivial
> + get_func_info watch
> +
> + if { $::version == 1 } {
> + set switch_file {}
> + } elseif { $::version == 2 } {
> + set switch_file { set f $f2 }
> + } else {
> + error "Unhandled version: $::version"
> + }
> +
> + cu {} {
> + compile_unit {
> + {language @DW_LANG_C}
> + {name dw2-prologue-end.c}
> + {stmt_list ${lines_label} DW_FORM_sec_offset}
> + {producer "clang version 17.0.1"}
> + } {
> + declare_labels char_label
> +
> + char_label: base_type {
> + {name char}
> + {encoding @DW_ATE_signed}
> + {byte_size 1 DW_FORM_sdata}
> + }
> +
> + subprogram {
> + {external 1 flag}
> + {name trivial}
> + {low_pc $trivial_start addr}
> + {high_pc "$trivial_start + $trivial_len" addr}
> + }
> + subprogram {
> + {external 1 flag}
> + {name watch}
> + {low_pc $watch_start addr}
> + {high_pc "$watch_start + $watch_len" addr}
> + } {
> + DW_TAG_variable {
> + {name local}
> + {type :$char_label}
> + {DW_AT_location {DW_OP_reg0} SPECIAL_expr}
> + }
> + }
> + subprogram {
> + {external 1 flag}
> + {name main}
> + {low_pc $main_start addr}
> + {high_pc "$main_start + $main_len" addr}
> + }
> + }
> + }
> +
> + lines {version 5} lines_label {
> + set diridx [include_dir "${srcdir}/${subdir}"]
> + set f1 [file_name "$srcfile" $diridx]
> + set f2 [file_name "$srcfile.inc" $diridx]
> +
> + set f $f1
> + program {
> + DW_LNS_set_file $f
> +
> + DW_LNE_set_address $trivial_start
> + line $trivial_line
> + DW_LNS_set_prologue_end
> + DW_LNS_set_epilogue_begin
> + DW_LNS_copy
> +
> + DW_LNE_set_address $trivial_end
> + DW_LNE_end_sequence
> +
> +
> + DW_LNS_set_file $f
> +
> + DW_LNE_set_address $watch_start
> + line $watch_start_line
> + DW_LNS_copy
> +
> + DW_LNE_set_address watch_start
> + line [gdb_get_line_number "watch assign"]
> + DW_LNS_set_prologue_end
> + DW_LNS_copy
> +
> + eval $switch_file
> + DW_LNS_set_file $f
> +
> + DW_LNE_set_address watch_reassign
> + line [gdb_get_line_number "watch reassign"]
> + DW_LNS_set_epilogue_begin
> + DW_LNS_copy
> +
> + DW_LNE_set_address watch_end
> + line [gdb_get_line_number "watch end"]
> + DW_LNS_copy
> +
> + DW_LNE_set_address $watch_end
> + DW_LNE_end_sequence
> +
> +
> + DW_LNS_set_file $f
> +
> + DW_LNE_set_address $main_start
> + line $main_prologue
> + DW_LNS_set_prologue_end
> + DW_LNS_copy
> +
> + DW_LNE_set_address main_fun_call
> + line [gdb_get_line_number "main function call"]
> + DW_LNS_copy
> +
> + DW_LNE_set_address main_epilogue
> + line $main_epilogue
> + DW_LNS_set_epilogue_begin
> + DW_LNS_copy
> +
> + DW_LNE_set_address $main_end
> + DW_LNE_end_sequence
> + }
> + }
> +}
> +
> +if { [prepare_for_testing "failed to prepare" ${testfile} \
> + [list $srcfile $asm_file] {nodebug}] } {
> + return -1
> +}
> +
> +if ![runto_main] {
> + return -1
> +}
> +
> +# Moving to the scope with a local variable.
> +
> +gdb_breakpoint $srcfile:$watch_start_line
> +gdb_continue_to_breakpoint "continuing to function" ".*"
> +gdb_test "next" "local = 2.*" "stepping to epilogue"
> +
> +# Forcing software watchpoints because hardware ones don't care if we
> +# are in the epilogue or not.
> +gdb_test_no_output "set can-use-hw-watchpoints 0"
> +
> +# Test that the software watchpoint will not trigger in this case
> +gdb_test "watch local" "\[W|w\]atchpoint .: local" "set watchpoint"
> +gdb_test "continue" ".*\[W|w\]atchpoint . deleted.*" \
> + "confirm watchpoint doesn't trigger"
> +
> +# First we test that the trivial function has a line with both a prologue
> +# and an epilogue. Do this by finding a line that has 3 Y columns
> +set sep "\[ \t\]"
> +set hex_number "0x\[0-9a-f\]+"
> +gdb_test_multiple "maint info line-table" "test epilogue in linetable" -lbl {
> + -re "\[0-9\]$sep+$trivial_line$sep+$hex_number$sep+$hex_number$sep+Y$sep+Y$sep+Y" {
> + pass $gdb_test_name
> + }
> +}
> diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
> index d085f835f07..adc3a18ee4f 100644
> --- a/gdb/testsuite/lib/dwarf.exp
> +++ b/gdb/testsuite/lib/dwarf.exp
> @@ -2427,10 +2427,11 @@ namespace eval Dwarf {
> variable _line_file_names
> lappend _line_file_names $filename $diridx
>
> + set nr_filenames [expr [llength $_line_file_names] / 2]
> if { $Dwarf::_line_unit_version >= 5 } {
> - return [expr [llength $_line_file_names] - 1]
> + return [expr $nr_filenames - 1]
> } else {
> - return [llength $_line_file_names]
> + return $nr_filenames
> }
> }
>
> --
> 2.35.3
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2024-04-22 15:53 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-04-09 9:27 [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access in find_epilogue_using_linetable Tom de Vries
2024-04-09 9:27 ` [PATCH v5 2/2] [gdb/symtab] Handle two-linetable function " Tom de Vries
2024-04-10 7:28 ` Bernd Edlinger
2024-04-22 13:39 ` Andrew Burgess
2024-04-11 13:59 ` [PATCH v5 1/2] [gdb/symtab] Fix an out of bounds array access " Bernd Edlinger
2024-04-22 13:22 ` Andrew Burgess
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