scripts/decodecode: add the capability to supply the program counter

So that comparing with objdump output from vmlinux can ease pinpointing
where the trapping instruction actually is.  An example is better than a
thousand words:

  $ PC=0xffffffff8329a927 ./scripts/decodecode < ~/tmp/syz/gfs2.splat
  [ 477.379104][T23917] Code: 48 83 ec 28 48 89 3c 24 48 89 54 24 08 e8 c1 b4 4a fe 48 8d bb 00 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 97 05 00 00 48 8b 9b 00 01 00 00 48 85 db 0f 84
  All code
  ========
  ffffffff8329a8fd:       48 83 ec 28             sub    $0x28,%rsp
  ffffffff8329a901:       48 89 3c 24             mov    %rdi,(%rsp)
  ffffffff8329a905:       48 89 54 24 08          mov    %rdx,0x8(%rsp)
  ffffffff8329a90a:       e8 c1 b4 4a fe          callq  0xffffffff81745dd0
  ffffffff8329a90f:       48 8d bb 00 01 00 00    lea    0x100(%rbx),%rdi
  ffffffff8329a916:       48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
  ffffffff8329a91d:       fc ff df
  ffffffff8329a920:       48 89 fa                mov    %rdi,%rdx
  ffffffff8329a923:       48 c1 ea 03             shr    $0x3,%rdx
  ffffffff8329a927:*      80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1)               <-- trapping instruction
  ffffffff8329a92b:       0f 85 97 05 00 00       jne    0xffffffff8329aec8
  ffffffff8329a931:       48 8b 9b 00 01 00 00    mov    0x100(%rbx),%rbx
  ffffffff8329a938:       48 85 db                test   %rbx,%rbx
  ffffffff8329a93b:       0f                      .byte 0xf
  ffffffff8329a93c:       84                      .byte 0x84

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Marc Zyngier <maz@misterjones.org>
Cc: Will Deacon <will@kernel.org>
Cc: Rabin Vincent <rabin@rab.in>
Link: https://lkml.kernel.org/r/20200930111416.GF6810@zn.tnic
Link: https://lkml.kernel.org/r/20200929113238.GC21110@zn.tnic
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions