| Message ID | 306f76fc-c445-6578-d4fe-5e462861920c@mir.dev (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] scripts/kallsyms: fix wrong kallsyms_relative_base | expand |
On Thu, Mar 12, 2020 at 5:37 AM Mikhail Petrov <Mikhail.Petrov@mir.dev> wrote: > > 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 > > Signed-off-by: Mikhail Petrov <Mikhail.Petrov@mir.dev> Applied with the following info: [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 is 'T' on binutils >= 2.23 The current minimal supported binutils version is 2.21 ] Thanks. > --- > > 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); > -- Best Regards Masahiro Yamada
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);
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 Signed-off-by: Mikhail Petrov <Mikhail.Petrov@mir.dev> ---