[Qemu-devel] qemu-x86_64: Error processing bextr

[Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>]

Hi

I have the following   assembly snipset (from get_common_indeces in
glibc compiled with gcc 6.3 -march=bdver4)

   0x00000040008179b3 <+19>: 89 15 8b c3 20 00 mov
%edx,0x20c38b(%rip)        # 0x4000a23d44 <_rtld_local_ro+132>
   0x00000040008179b9 <+25>: 89 1d 7d c3 20 00 mov
%ebx,0x20c37d(%rip)        # 0x4000a23d3c <_rtld_local_ro+124>
   0x00000040008179bf <+31>: 8f ea 78 10 d0 08 04 00 00 bextr  $0x408,%eax,%edx
   0x00000040008179c8 <+40>: 89 0d 72 c3 20 00 mov
%ecx,0x20c372(%rip)        # 0x4000a23d40 <_rtld_local_ro+128>
   0x00000040008179ce <+46>: 89 05 64 c3 20 00 mov
%eax,0x20c364(%rip)        # 0x4000a23d38 <_rtld_local_ro+120>


When I run the application using qemu-x86-64, the instruction bextr is
not understood by the emulator and results in a SIGSEGV, because it
runs:

0x00000040008179b9: mov    %ebx,0x20c37d(%rip)        # 0x4000a23d3c
0x00000040008179bf: (bad)
0x00000040008179c0: (bad)
0x00000040008179c1: js     0x40008179d3
0x00000040008179c3: rorb   (%rax)


It seems that, bextr is not supported by the emulator/cpu, althoug I
have launched the emualtor with -cpu Haswell, that should support bmi1
(https://en.wikipedia.org/wiki/Bit_Manipulation_Instruction_Sets#BMI1)

What am I doing wrong?


Thanks!


cc: Richard Henderson and Blue Swril, that Implemented BEXTR
-- 
Ricardo Ribalda