From: Jan Kratochvil <jan.kratochvil@redhat.com>
To: gdb-patches@sourceware.org
Cc: Sergio Durigan Junior <sergiodj@redhat.com>
Subject: [patch] Do not skip prologue for asm (.S) files
Date: Sat, 20 Jun 2015 15:44:00 -0000 [thread overview]
Message-ID: <20150620154449.GA24593@host1.jankratochvil.net> (raw)
[-- Attachment #1: Type: text/plain, Size: 2080 bytes --]
Hi,
https://bugzilla.redhat.com/show_bug.cgi?id=1084404
GDB tries to skip prologue for .S files according to .debug_line but it then
places the breakpoint to a location where it is never hit.
This is because #defines in .S files cause prologue skipping which is
completely inappropriate, for s390x:
glibc/sysdeps/unix/syscall-template.S
78:/* This is a "normal" system call stub: if there is an error,
79: it returns -1 and sets errno. */
80:
81:T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
82: ret
00000000000f4210 T __select
Line Number Statements:
Extended opcode 2: set Address to 0xf41c8
Advance Line by 80 to 81
Copy
Advance PC by 102 to 0xf422e
Special opcode 6: advance Address by 0 to 0xf422e and Line by 1 to 82
Special opcode 34: advance Address by 2 to 0xf4230 and Line by 1 to 83
Advance PC by 38 to 0xf4256
Extended opcode 1: End of Sequence
Compilation Unit @ offset 0x28b3e0:
<0><28b3eb>: Abbrev Number: 1 (DW_TAG_compile_unit)
<28b3ec> DW_AT_stmt_list : 0x7b439
<28b3f0> DW_AT_low_pc : 0xf41c8
<28b3f8> DW_AT_high_pc : 0xf4256
<28b400> DW_AT_name : ../sysdeps/unix/syscall-template.S
<28b423> DW_AT_comp_dir : /usr/src/debug////////glibc-2.17-c758a686/misc
<28b452> DW_AT_producer : GNU AS 2.23.52.0.1
<28b465> DW_AT_language : 32769 (MIPS assembler)
without debuginfo - correct address:
(gdb) b select
Breakpoint 1 at 0xf4210
with debuginfo, either with or without the fix:
(gdb) b select
Breakpoint 1 at 0xf41c8: file ../sysdeps/unix/syscall-template.S, line 81.
One part is to make 'locations_valid' true even for asm files.
/* Symtab has been compiled with both optimizations and debug info so that
GDB may stop skipping prologues as variables locations are valid already
at function entry points. */
unsigned int locations_valid : 1;
The other part is to extend the 'locations_valid' functionality more - I have
chosen mostly randomly this place.
No regressions on {x86_64,x86_64-m32,i686}-fedora23pre-linux-gnu.
Jan
[-- Attachment #2: locvalid3.patch --]
[-- Type: text/plain, Size: 4359 bytes --]
gdb/ChangeLog
2015-06-20 Jan Kratochvil <jan.kratochvil@redhat.com>
* dwarf2read.c (process_full_comp_unit): Set LOCATIONS_VALID also for
language_asm.
* linespec.c (minsym_found): Reset sal.PC forCOMPUNIT_LOCATIONS_VALID.
gdb/testsuite/ChangeLog
2015-06-20 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.arch/amd64-prologue-skip.S: New file.
* gdb.arch/amd64-prologue-skip.exp: New file.
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index d79b2e3..76ff66d 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -8096,7 +8096,7 @@ process_full_comp_unit (struct dwarf2_per_cu_data *per_cu,
Still one can confuse GDB by using non-standard GCC compilation
options - this waits on GCC PR other/32998 (-frecord-gcc-switches).
*/
- if (cu->has_loclist && gcc_4_minor >= 5)
+ if ((cu->has_loclist && gcc_4_minor >= 5) || cu->language == language_asm)
cust->locations_valid = 1;
if (gcc_4_minor >= 5)
diff --git a/gdb/linespec.c b/gdb/linespec.c
index d2089b5..a7ea41b 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -3454,7 +3454,17 @@ minsym_found (struct linespec_state *self, struct objfile *objfile,
sal = find_pc_sect_line (pc, NULL, 0);
if (self->funfirstline)
- skip_prologue_sal (&sal);
+ {
+ if (sal.symtab != NULL
+ && COMPUNIT_LOCATIONS_VALID (SYMTAB_COMPUNIT (sal.symtab)))
+ {
+ sal.pc = MSYMBOL_VALUE_ADDRESS (objfile, msymbol);
+ sal.pc = gdbarch_convert_from_func_ptr_addr (gdbarch, sal.pc,
+ ¤t_target);
+ }
+ else
+ skip_prologue_sal (&sal);
+ }
if (maybe_add_address (self->addr_set, objfile->pspace, sal.pc))
add_sal_to_sals (self, result, &sal, MSYMBOL_NATURAL_NAME (msymbol), 0);
diff --git a/gdb/testsuite/gdb.arch/amd64-prologue-skip.S b/gdb/testsuite/gdb.arch/amd64-prologue-skip.S
new file mode 100644
index 0000000..66b806a
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/amd64-prologue-skip.S
@@ -0,0 +1,28 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2015 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/>. */
+
+ .text
+/*0*/ hlt
+pushrbp: .globl pushrbp
+#define PUSHRBP push %rbp; mov %rsp, %rbp; nop
+/*1*/ PUSHRBP
+/*6*/ hlt
+
+/*7*/ hlt
+#define MINSYM nop; .globl minsym; minsym: nop
+/*8*/ MINSYM
+/*a*/ hlt
diff --git a/gdb/testsuite/gdb.arch/amd64-prologue-skip.exp b/gdb/testsuite/gdb.arch/amd64-prologue-skip.exp
new file mode 100644
index 0000000..015cd69
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/amd64-prologue-skip.exp
@@ -0,0 +1,35 @@
+# Copyright 2010-2015 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 .S
+set binfile ${binfile}.o
+
+if { ![istarget x86_64-*-* ] || ![is_lp64_target] } {
+ verbose "Skipping ${testfile}."
+ return
+}
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" object {debug}] != "" } {
+ untested ${testfile}
+ return
+}
+
+clean_restart ${binfile}
+
+gdb_test "break *pushrbp" " at 0x1: file .*"
+gdb_test "break pushrbp" " at 0x1: file .*"
+
+gdb_test "break *minsym" " at 0x9: file .*"
+gdb_test "break minsym" " at 0x9: file .*"
next reply other threads:[~2015-06-20 15:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-20 15:44 Jan Kratochvil [this message]
2015-06-21 22:52 ` Doug Evans
2015-06-22 21:16 ` Jan Kratochvil
2015-06-22 23:46 ` Doug Evans
2015-06-23 20:35 ` Jan Kratochvil
2015-06-24 20:20 ` Jan Kratochvil
2015-06-25 15:47 ` [patchv2] " Jan Kratochvil
2015-06-25 20:30 [patch] " Doug Evans
2015-06-25 20:37 ` Jan Kratochvil
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