path: root/scripts/kallsyms.c
diff options
authorMikhail Petrov <Mikhail.Petrov@mir.dev>2020-03-11 23:37:09 +0300
committerMasahiro Yamada <masahiroy@kernel.org>2020-03-19 23:40:20 +0900
commit7883a14339299773b2ce08dcfd97c63c199a9289 (patch)
tree5edb449474faa1d9d5d32d624025eea3c9a68e47 /scripts/kallsyms.c
parentmodpost: Get proper section index by get_secindex() instead of st_shndx (diff)
scripts/kallsyms: fix wrong kallsyms_relative_base
There is the code in the read_symbol function in 'scripts/kallsyms.c': if (is_ignored_symbol(name, type)) return NULL; /* Ignore most absolute/undefined (?) symbols. */ if (strcmp(name, "_text") == 0) _text = addr; But the is_ignored_symbol function returns true for name="_text" and type='A'. So the next condition is not executed and the _text variable is always zero. It makes the wrong kallsyms_relative_base symbol as a result of the code (CONFIG_KALLSYMS_BASE_RELATIVE is defined): if (base_relative) { output_label("kallsyms_relative_base"); output_address(relative_base); printf("\n"); } Because the output_address function uses the _text variable. So the kallsyms_lookup function and all related functions in the kernel do not work properly. For example, the stack trace in oops: Call Trace: [aa095e58] [809feab8] kobj_ns_ops_tbl+0x7ff09ac8/0x7ff1c1c4 (unreliable) [aa095e98] [80002b64] kobj_ns_ops_tbl+0x7f50db74/0x80000010 [aa095ef8] [809c3d24] kobj_ns_ops_tbl+0x7feced34/0x7ff1c1c4 [aa095f28] [80002ed0] kobj_ns_ops_tbl+0x7f50dee0/0x80000010 [aa095f38] [8000f238] kobj_ns_ops_tbl+0x7f51a248/0x80000010 The right stack trace: Call Trace: [aa095e58] [809feab8] module_vdu_video_init+0x2fc/0x3bc (unreliable) [aa095e98] [80002b64] do_one_initcall+0x40/0x1f0 [aa095ef8] [809c3d24] kernel_init_freeable+0x164/0x1d8 [aa095f28] [80002ed0] kernel_init+0x14/0x124 [aa095f38] [8000f238] ret_from_kernel_thread+0x14/0x1c [masahiroy@kernel.org: This issue happens on binutils <= 2.22 The following commit fixed it: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d2667025dd30611514810c28bee9709e4623012a The symbol type of _text is 'T' on binutils >= 2.23 The minimal supported binutils version for the kernel build is 2.21 ] Signed-off-by: Mikhail Petrov <Mikhail.Petrov@mir.dev> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'scripts/kallsyms.c')
1 files changed, 4 insertions, 4 deletions
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 0133dfaaf352..3e8dea6e0a95 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -195,13 +195,13 @@ static struct sym_entry *read_symbol(FILE *in)
return NULL;
- if (is_ignored_symbol(name, type))
- return NULL;
- /* Ignore most absolute/undefined (?) symbols. */
if (strcmp(name, "_text") == 0)
_text = addr;
+ /* Ignore most absolute/undefined (?) symbols. */
+ if (is_ignored_symbol(name, type))
+ return NULL;
check_symbol_range(name, addr, text_ranges, ARRAY_SIZE(text_ranges));
check_symbol_range(name, addr, &percpu_range, 1);