* [committed][multi-file] Handle intra-CU DW_FORM_ref_addr reference
2019-01-01 0:00 [PATCH] [multi-file] Handle DW_FORM_ref_addr reference that points to containing unit Tom de Vries
@ 2019-01-01 0:00 ` Tom de Vries
0 siblings, 0 replies; 2+ messages in thread
From: Tom de Vries @ 2019-01-01 0:00 UTC (permalink / raw)
To: dwz, jakub, Mark Wielaard
[-- Attachment #1: Type: text/plain, Size: 1015 bytes --]
[ was: [PATCH] [multi-file] Handle DW_FORM_ref_addr reference that
points to containing unit ]
On 07-03-19 08:36, Tom de Vries wrote:
> [ Submitted earlier off-list ]
>
> Hi,
>
> For test-cases with DW_FORM_ref_addr attributes that point to within the CU
> containing the attribute, we run into the following assert in multifile mode:
> ...
> dwz: dwz.c:1984: checksum_die: Assertion `
> ((!op_multifile && !rd_multifile && !fi_multifile) || cu != die_cu (ref))
> && (!op_multifile || cu->cu_chunk == die_cu (ref)->cu_chunk)
> ' failed.
> ...
>
> This conservative fix detects the situation, and instead of asserting stops
> further processing of the DIE.
>
I've committed this version, which:
- does essentially the same fix
- has a more elaborate rationale
- adds comments
- is more minimal (remaining assert still checks op_multifile and
rd_multifile).
- includes a test-case (which happens to break the buildbot for
dwz-debian-armhf and dwz-debian-i386), I'll push a fix shortly.
Thanks,
- Tom
[-- Attachment #2: 0001-multi-file-Handle-intra-CU-DW_FORM_ref_addr-reference.patch --]
[-- Type: text/x-patch, Size: 13651 bytes --]
[multi-file] Handle intra-CU DW_FORM_ref_addr reference
When self-dwz-m-ing the implptr-64bit-d2o4a8r8t0 test-case, we run into the
following assert in multifile mode:
...
dwz: dwz.c:2363: checksum_die: Assertion `
((!op_multifile && !rd_multifile && !fi_multifile) || cu != die_cu (ref))
&& (!op_multifile || cu->cu_chunk == die_cu (ref)->cu_chunk)
' failed.
...
The test-case contains a DIE:
...
<1><110>: Abbrev Number: 8 (DW_TAG_subprogram)
<111> DW_AT_name : main
<116> DW_AT_low_pc : 0x400497
<11e> DW_AT_high_pc : 0x400597
<126> DW_AT_type : <0xe4>
<12e> DW_AT_external : 1
...
with DW_AT_type referring to a DIE at 0xe4:
...
<1><e4>: Abbrev Number: 3 (DW_TAG_base_type)
<e5> DW_AT_byte_size : 4
<e6> DW_AT_encoding : 5 (signed)
<e7> DW_AT_name : int
...
using a section-relative encoding DW_FORM_ref_addr:
...
8 DW_TAG_subprogram [has children]
DW_AT_name DW_FORM_string
DW_AT_low_pc DW_FORM_addr
DW_AT_high_pc DW_FORM_addr
DW_AT_type DW_FORM_ref_addr
DW_AT_external DW_FORM_flag
DW_AT value: 0 DW_FORM value: 0
...
[ This is not incorrect, merely unoptimal. The DW_FORM_ref_addr reference uses
4 bytes, while it could have been encoded with DW_FORM_ref1 using only 1
byte. ]
This part of the assert triggers during finalize_multifile:
...
((!op_multifile && !rd_multifile && !fi_multifile) || cu != die_cu (ref))
...
Since the offending reference is part of the input DWARF, and there's nothing
to guarantee that it will be removed during single-file optimization, we can
expect it to occur during finalize_multifile.
This conservative fix detects the situation, and instead of asserting stops
further processing of the DIE.
2019-06-25 Tom de Vries <tdevries@suse.de>
PR dwz/24170
* dwz.c (checksum_die): Handle intra-CU DW_FORM_ref_addr references
conservatively.
* testsuite/dwz.tests/implptr-64bit-d2o4a8r8t0.S: New test source.
* testsuite/dwz.tests/main.c: Same.
* testsuite/dwz.tests/pr24170.sh: New test.
---
Makefile | 5 +-
dwz.c | 31 ++++-
testsuite/dwz.tests/implptr-64bit-d2o4a8r8t0.S | 156 +++++++++++++++++++++++++
testsuite/dwz.tests/main.c | 5 +
testsuite/dwz.tests/pr24170.sh | 16 +++
5 files changed, 208 insertions(+), 5 deletions(-)
diff --git a/Makefile b/Makefile
index f039b4d..45ca3d2 100644
--- a/Makefile
+++ b/Makefile
@@ -24,7 +24,7 @@ PWD:=$(shell pwd -P)
TEST_SRC = $(srcdir)/testsuite/dwz.tests
TEST_EXECS = hello dw2-restrict py-section-script dwz-for-test min two-typedef \
- dw2-skip-prologue start
+ dw2-skip-prologue start implptr-64bit-d2o4a8r8t0
hello:
$(CC) $(TEST_SRC)/hello.c -o $@ -g
@@ -58,6 +58,9 @@ two-typedef:
start:
$(CC) $(TEST_SRC)/start.c -o $@ -g -nostdlib
+implptr-64bit-d2o4a8r8t0:
+ $(CC) $(TEST_SRC)/implptr-64bit-d2o4a8r8t0.S $(TEST_SRC)/main.c -o $@ -g
+
# On some systems we need to set and export DEJAGNU to suppress
# WARNING: Couldn't find the global config file.
DEJAGNU ?= /dev/null
diff --git a/dwz.c b/dwz.c
index 6f34a0c..9e39824 100644
--- a/dwz.c
+++ b/dwz.c
@@ -2357,10 +2357,33 @@ checksum_die (DSO *dso, dw_cu_ref cu, dw_die_ref top_die, dw_die_ref die)
}
if (unlikely (op_multifile) && ref->die_collapsed_child)
ref = ref->die_parent;
- assert (((!op_multifile && !rd_multifile && !fi_multifile)
- || cu != die_cu (ref))
- && (!op_multifile
- || cu->cu_chunk == die_cu (ref)->cu_chunk));
+ if (cu == die_cu (ref))
+ {
+ /* The reference was encoded using a section-relative
+ encoding, while if it could have been encoded using
+ CU-relative encoding. Typically, the latter is used,
+ because:
+ - it's potentially smaller, and
+ - it doesn't require a link-time relocation. */
+
+ /* Assert that the multifile only contains section-relative
+ encoding when necessary. */
+ assert (!op_multifile && !rd_multifile);
+
+ if (fi_multifile)
+ {
+ /* It's possible that the input DWARF contains this
+ sub-optimal reference. We currently don't optimize
+ this during single-file optimization, so it will still
+ be there during finalize_multifile. Bail out to handle
+ this conservatively. */
+ die->die_ck_state = CK_BAD;
+ return 0;
+ }
+ }
+ /* Assert that during op_multifile, die belongs to the same object
+ as ref. */
+ assert (!op_multifile || cu->cu_chunk == die_cu (ref)->cu_chunk);
handled = true;
break;
}
diff --git a/testsuite/dwz.tests/implptr-64bit-d2o4a8r8t0.S b/testsuite/dwz.tests/implptr-64bit-d2o4a8r8t0.S
new file mode 100644
index 0000000..7c41f5b
--- /dev/null
+++ b/testsuite/dwz.tests/implptr-64bit-d2o4a8r8t0.S
@@ -0,0 +1,156 @@
+/* This was generated using git://sourceware.org/git/binutils-gdb.git
+ repository, file gdb/testsuite/gdb.dwarf2/implptr-64bit.exp. */
+ .section .debug_info
+.Lcu1_begin:
+ .4byte .Lcu1_end - .Lcu1_start
+.Lcu1_start:
+ .2byte 2 /* Version */
+ .4byte .Labbrev1_begin /* Abbrevs */
+ .byte 8 /* Pointer size */
+ .uleb128 2 /* Abbrev (DW_TAG_compile_unit) */
+ .ascii "GNU C 4.4.3\0"
+ .sleb128 0x0001
+ .ascii "1.c\0"
+.Llabel3:
+ .uleb128 3 /* Abbrev (DW_TAG_base_type) */
+ .sleb128 4
+ .sleb128 0x5
+ .ascii "int\0"
+.Llabel1:
+ .uleb128 4 /* Abbrev (DW_TAG_structure_type) */
+ .ascii "s\0"
+ .sleb128 4
+ .uleb128 5 /* Abbrev (DW_TAG_member) */
+ .ascii "f\0"
+ .4byte .Llabel3 - .Lcu1_begin
+ .byte 0
+ .byte 0x0 /* Terminate children */
+.Llabel4:
+ .uleb128 6 /* Abbrev (DW_TAG_pointer_type) */
+ .sleb128 8
+ .4byte .Llabel1 - .Lcu1_begin
+.Llabel2:
+ .uleb128 7 /* Abbrev (DW_TAG_variable) */
+ .ascii "v\0"
+ .uleb128 .Lexpr_end6 - .Lexpr_start5/* expression */
+.Lexpr_start5:
+ .byte 0x9e /* DW_OP_implicit_value */
+ .uleb128 .Lvalue_end8 - .Lvalue_start7
+.Lvalue_start7:
+ .byte 0x1
+ .byte 0x1
+ .byte 0x1
+ .byte 0x1
+.Lvalue_end8:
+.Lexpr_end6:
+ .8byte .Llabel1 - .Lcu1_begin
+ .uleb128 8 /* Abbrev (DW_TAG_subprogram) */
+ .ascii "main\0"
+ .8byte main
+ .8byte main+0x100
+ .8byte .Llabel3
+ .byte 1
+ .uleb128 9 /* Abbrev (DW_TAG_variable) */
+ .ascii "p\0"
+ .uleb128 .Lexpr_end10 - .Lexpr_start9/* expression */
+.Lexpr_start9:
+ .byte 0xf2 /* DW_OP_GNU_implicit_pointer */
+ .8byte .Llabel2
+ .sleb128 0
+.Lexpr_end10:
+ .8byte .Llabel4 - .Lcu1_begin
+ .byte 0x0 /* Terminate children */
+ .byte 0x0 /* Terminate children */
+.Lcu1_end:
+ .section .debug_abbrev
+.Labbrev1_begin:
+ .uleb128 2 /* Abbrev start */
+ .uleb128 0x11 /* DW_TAG_compile_unit */
+ .byte 1 /* has_children */
+ .uleb128 0x25 /* DW_AT_producer */
+ .uleb128 0x08 /* DW_FORM_string */
+ .uleb128 0x13 /* DW_AT_language */
+ .uleb128 0x0d /* DW_FORM_sdata */
+ .uleb128 0x03 /* DW_AT_name */
+ .uleb128 0x08 /* DW_FORM_string */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .uleb128 3 /* Abbrev start */
+ .uleb128 0x24 /* DW_TAG_base_type */
+ .byte 0 /* has_children */
+ .uleb128 0x0b /* DW_AT_byte_size */
+ .uleb128 0x0d /* DW_FORM_sdata */
+ .uleb128 0x3e /* DW_AT_encoding */
+ .uleb128 0x0d /* DW_FORM_sdata */
+ .uleb128 0x03 /* DW_AT_name */
+ .uleb128 0x08 /* DW_FORM_string */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .uleb128 4 /* Abbrev start */
+ .uleb128 0x13 /* DW_TAG_structure_type */
+ .byte 1 /* has_children */
+ .uleb128 0x03 /* DW_AT_name */
+ .uleb128 0x08 /* DW_FORM_string */
+ .uleb128 0x0b /* DW_AT_byte_size */
+ .uleb128 0x0d /* DW_FORM_sdata */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .uleb128 5 /* Abbrev start */
+ .uleb128 0x0d /* DW_TAG_member */
+ .byte 0 /* has_children */
+ .uleb128 0x03 /* DW_AT_name */
+ .uleb128 0x08 /* DW_FORM_string */
+ .uleb128 0x49 /* DW_AT_type */
+ .uleb128 0x13 /* DW_FORM_ref4 */
+ .uleb128 0x38 /* DW_AT_data_member_location */
+ .uleb128 0x0b /* DW_FORM_data1 */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .uleb128 6 /* Abbrev start */
+ .uleb128 0x0f /* DW_TAG_pointer_type */
+ .byte 0 /* has_children */
+ .uleb128 0x0b /* DW_AT_byte_size */
+ .uleb128 0x0d /* DW_FORM_sdata */
+ .uleb128 0x49 /* DW_AT_type */
+ .uleb128 0x13 /* DW_FORM_ref4 */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .uleb128 7 /* Abbrev start */
+ .uleb128 0x34 /* DW_TAG_variable */
+ .byte 0 /* has_children */
+ .uleb128 0x03 /* DW_AT_name */
+ .uleb128 0x08 /* DW_FORM_string */
+ .uleb128 0x02 /* DW_AT_location */
+ .uleb128 0x09 /* SPECIAL_expr */
+ .uleb128 0x49 /* DW_AT_type */
+ .uleb128 0x14 /* DW_FORM_ref8 */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .uleb128 8 /* Abbrev start */
+ .uleb128 0x2e /* DW_TAG_subprogram */
+ .byte 1 /* has_children */
+ .uleb128 0x03 /* DW_AT_name */
+ .uleb128 0x08 /* DW_FORM_string */
+ .uleb128 0x11 /* DW_AT_low_pc */
+ .uleb128 0x01 /* DW_FORM_addr */
+ .uleb128 0x12 /* DW_AT_high_pc */
+ .uleb128 0x01 /* DW_FORM_addr */
+ .uleb128 0x49 /* DW_AT_type */
+ .uleb128 0x10 /* DW_FORM_ref_addr */
+ .uleb128 0x3f /* DW_AT_external */
+ .uleb128 0x0c /* DW_FORM_flag */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .uleb128 9 /* Abbrev start */
+ .uleb128 0x34 /* DW_TAG_variable */
+ .byte 0 /* has_children */
+ .uleb128 0x03 /* DW_AT_name */
+ .uleb128 0x08 /* DW_FORM_string */
+ .uleb128 0x02 /* DW_AT_location */
+ .uleb128 0x09 /* SPECIAL_expr */
+ .uleb128 0x49 /* DW_AT_type */
+ .uleb128 0x14 /* DW_FORM_ref8 */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
+ .byte 0x0 /* Terminator */
diff --git a/testsuite/dwz.tests/main.c b/testsuite/dwz.tests/main.c
new file mode 100644
index 0000000..398ec67
--- /dev/null
+++ b/testsuite/dwz.tests/main.c
@@ -0,0 +1,5 @@
+int
+main (void)
+{
+ return 0;
+}
diff --git a/testsuite/dwz.tests/pr24170.sh b/testsuite/dwz.tests/pr24170.sh
new file mode 100644
index 0000000..20fe339
--- /dev/null
+++ b/testsuite/dwz.tests/pr24170.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+exec=$execs/implptr-64bit-d2o4a8r8t0
+
+cp $exec 1
+cp 1 2
+
+dwz -m 3 1 2
+
+smaller-than.sh 1 $exec
+smaller-than.sh 2 $exec
+
+[ "$(gnu-debugaltlink-name.sh 1)" = "3" ]
+[ "$(gnu-debugaltlink-name.sh 2)" = "3" ]
+
+rm -f 1 2 3
^ permalink raw reply [flat|nested] 2+ messages in thread