Messages in this thread | | | Date | Tue, 19 Apr 2022 22:14:35 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2] scripts: Create objdump-func helper script |
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On Tue, Apr 19, 2022 at 09:50:01PM +0200, Borislav Petkov wrote: > On Tue, Apr 19, 2022 at 09:12:23AM -0700, Josh Poimboeuf wrote: > > Add a simple script which disassembles a single function from an object > > file. Comes in handy for objtool warnings and kernel stack traces. > > > > Originally-by: Peter Zijlstra <peterz@infradead.org> > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > > --- > > v2: > > - require gawk > > > > scripts/objdump-func | 18 ++++++++++++++++++ > > 1 file changed, 18 insertions(+) > > create mode 100755 scripts/objdump-func > > Was that supposed to be user-friendly too? > > $ ./scripts/objdump-func -h > ./scripts/objdump-func: line 16: $1: unbound variable > > :-) > > > It works tho: > > $ ./scripts/objdump-func vmlinux rewind_stack_and_make_dead > 0000 ffffffff81001c00 <rewind_stack_and_make_dead>: > 0000 ffffffff81001c00: 31 ed xor %ebp,%ebp > 0000 ffffffff81001c02: 65 48 8b 04 25 d0 ec 01 00 mov %gs:0x1ecd0,%rax > 0000 ffffffff81001c0b: 48 8d a0 58 ff ff ff lea -0xa8(%rax),%rsp > 0000 ffffffff81001c12: e8 39 24 07 00 call ffffffff81074050 <make_task_dead> > ^^^^ > > I guess those zeros at the beginning are supposed to mean something...
Use the .o file and it'll work:
$ ./objdump-func.sh defconfig-build/vmlinux.o rewind_stack_and_make_dead 0000 0000000000001380 <rewind_stack_and_make_dead>: 0000 1380: 31 ed xor %ebp,%ebp 0002 1382: 65 48 8b 04 25 00 00 00 00 mov %gs:0x0,%rax 1387: R_X86_64_32S cpu_current_top_of_stack 000b 138b: 48 8d a0 58 ff ff ff lea -0xa8(%rax),%rsp 0012 1392: e8 00 00 00 00 call 1397 <preempt_schedule_thunk> 1393: R_X86_64_PLT32 make_task_dead-0x4
Now the first coloumn is the symbol relative offset, while the second column is the section relative offset objdump normally gives you.
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