Re: [Crash-utility] [PATCH] Fix for "dis" command to correctly display the offset of disassembly code

On 2023/02/21 12:03, Lianbo Jiang wrote: > For gdb-10.2, the disassembly code may start with "=>", which needs to > be stripped when calculating the address. Otherwise, parsing the address > will fail because the current code always assumes that it starts with the > "0x". For example: > > crash> gdb disassemble 0xffffffffa2317add > Dump of assembler code for function native_queued_spin_lock_slowpath: > 0xffffffffa2317ab0 <+0>: nopl 0x0(%rax,%rax,1) > 0xffffffffa2317ab5 <+5>: push %rbp > 0xffffffffa2317ab6 <+6>: mov %rsp,%rbp > ... > 0xffffffffa2317ad3 <+35>: mov %edx,%eax > 0xffffffffa2317ad5 <+37>: lock cmpxchg %ecx,(%rdi) > => 0xffffffffa2317ad9 <+41>: cmp %eax,%edx > 0xffffffffa2317adb <+43>: jne 0xffffffffa2317ac0 <native_queued_spin_lock_slowpath+16> > 0xffffffffa2317add <+45>: pop %rbp > 0xffffffffa2317ade <+46>: xchg %ax,%ax > ... Probably the following prints the "=> ". Out of curiosity, what did you do before the gdb disas?

"=> " for current instruction, else " ". */ const char * pc_prefix (CORE_ADDR addr) { if (has_stack_frames ()) { struct frame_info *frame; CORE_ADDR pc; frame = get_selected_frame (NULL); if (get_frame_pc_if_available (frame, &pc) && pc == addr) return "=> "; } return " "; } Anyway, the patch looks good to me. Acked-by: Kazuhito Hagio <k-hagio-ab(a)nec.com&gt; Thanks, Kazu > > Without the patch: > crash> dis 0xffffffffa2317add -r | tail -5 > 0xffffffffa2317ad3 <native_queued_spin_lock_slowpath+35>: mov %edx,%eax > 0xffffffffa2317ad5 <native_queued_spin_lock_slowpath+37>: lock cmpxchg %ecx,(%rdi) > 0xffffffffa2317ad5 <native_queued_spin_lock_slowpath+37>: cmp %eax,%edx > ^^^ > 0xffffffffa2317adb <native_queued_spin_lock_slowpath+43>: jne 0xffffffffa2317ac0 <native_queued_spin_lock_slowpath+16> > 0xffffffffa2317add <native_queued_spin_lock_slowpath+45>: pop %rbp > > With the patch: > crash> dis 0xffffffffa2317add -r | tail -5 > 0xffffffffa2317ad3 <native_queued_spin_lock_slowpath+35>: mov %edx,%eax > 0xffffffffa2317ad5 <native_queued_spin_lock_slowpath+37>: lock cmpxchg %ecx,(%rdi) > 0xffffffffa2317ad9 <native_queued_spin_lock_slowpath+41>: cmp %eax,%edx > 0xffffffffa2317adb <native_queued_spin_lock_slowpath+43>: jne 0xffffffffa2317ac0 <native_queued_spin_lock_slowpath+16> > 0xffffffffa2317add <native_queued_spin_lock_slowpath+45>: pop %rbp > > Reported-by: Vernon Lovejoy <vlovejoy(a)redhat.com&gt; > Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; > --- > kernel.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/kernel.c b/kernel.c > index a42e6ad7d78c..6e98f5f6f6b1 100644 > --- a/kernel.c > +++ b/kernel.c > @@ -2112,6 +2112,10 @@ cmd_dis(void) > rewind(pc->tmpfile); > > while (fgets(buf2, BUFSIZE, pc->tmpfile)) { > + > + if (STRNEQ(buf2, "=>")) > + shift_string_left(buf2, 2); > + > strip_beginning_whitespace(buf2); > > if (do_load_module_filter)