dwarf_loader: Support DW_TAG_label outside DW_TAG_lexblock
This happens with asm CUs, noticed when building the Linux kernel with
clang 15, where we have, for instance:
Contents of the .debug_info section:
Compilation Unit @ offset 0x0:
Length: 0x1df (32-bit)
Version: 5
Unit Type: DW_UT_compile (1)
Abbrev Offset: 0x0
Pointer Size: 8
<0><c>: Abbrev Number: 1 (DW_TAG_compile_unit)
<d> DW_AT_stmt_list : 0x0
<11> DW_AT_ranges : 0xc
<15> DW_AT_name : arch/x86/kernel/verify_cpu.S
<32> DW_AT_comp_dir : /home/nathan/cbl/src/linux
<4d> DW_AT_producer : ClangBuiltLinux clang version 16.0.0 (https://github.com/llvm/llvm-project 7e22179d38c438fedb0d9bb0cff1585843bd7082)
<c2> DW_AT_language : 32769 (MIPS assembler)
<1><c4>: Abbrev Number: 2 (DW_TAG_label)
<c5> DW_AT_name : startup_64
<d0> DW_AT_decl_file : 0x0
<d4> DW_AT_decl_line : 0x364
<d8> DW_AT_low_pc : 0xffffffff81000000
<1><e0>: Abbrev Number: 2 (DW_TAG_label)
<e1> DW_AT_name : secondary_startup_64
<f6> DW_AT_decl_file : 0x0
<fa> DW_AT_decl_line : 0x399
<fe> DW_AT_low_pc : 0xffffffff81000060
<1><106>: Abbrev Number: 2 (DW_TAG_label)
<107> DW_AT_name : secondary_startup_64_no_verify
<126> DW_AT_decl_file : 0x0
<12a> DW_AT_decl_line : 0x39f
<12e> DW_AT_low_pc : 0xffffffff81000065
<1><136>: Abbrev Number: 2 (DW_TAG_label)
<137> DW_AT_name : verify_cpu
<142> DW_AT_decl_file : 0x0
<146> DW_AT_decl_line : 0x430
<14a> DW_AT_low_pc : 0xffffffff81000150
<SNIP>
Bug: 261824655
Reported-by: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/dwarves/YzWSzXKcm6rSWOC5@kernel.org
Change-Id: Iefa1632a9307b57e11ca7f6a59bf86fd7b8cfd71
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/dwarf_loader.c b/dwarf_loader.c
index e30b03c..2ea901c 100644
--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -1472,7 +1472,12 @@
if (label == NULL)
return NULL;
- lexblock__add_label(lexblock, label);
+ if (lexblock != NULL) {
+ // asm CUs have labels and they will be in the cu top level tag list
+ // See die__process_unit()
+ lexblock__add_label(lexblock, label);
+ }
+
return &label->ip.tag;
}
@@ -2023,6 +2028,12 @@
*/
tag = &unsupported_tag;
break;
+ case DW_TAG_label:
+ if (conf->ignore_labels)
+ tag = &unsupported_tag; // callers will assume conf->ignore_labels is true
+ else // We can have labels in asm CUs, no lexblock
+ tag = die__create_new_label(die, NULL, cu, conf);
+ break;
}
if (tag != NULL)
@@ -2041,7 +2052,8 @@
if (tag == &unsupported_tag) {
// XXX special case DW_TAG_dwarf_procedure, appears when looking at a recent ~/bin/perf
// Investigate later how to properly support this...
- if (dwarf_tag(die) != DW_TAG_dwarf_procedure)
+ if (dwarf_tag(die) != DW_TAG_dwarf_procedure &&
+ dwarf_tag(die) != DW_TAG_label) // conf->ignore_labels == true, see die__process_tag()
tag__print_not_supported(dwarf_tag(die));
continue;
}
