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Description of problem:
Please add support to gdb and crash to decode the new CLFLUSHOPT instruction (in Intel Skylake and newer CPUs). Currently gdb shows the 0x66 prefix as a separate instruction, but objdump decodes it correctly:
$ echo 'int main(void) { asm volatile("clflushopt (%rdi)"); }' > clflushopt.c
$ gcc -g clflushopt.c
$ objdump -d a.out | grep clflush
4004f4: 66 0f ae 3f clflushopt (%rdi)
$ gdb -q ./a.out
Reading symbols from /tmp/clflushopt/a.out...done.
(gdb) disas /r main
Dump of assembler code for function main:
...
0x00000000004004f4 <+4>: 66 data16
0x00000000004004f5 <+5>: 0f ae 3f clflush (%rdi)
Version-Release number of selected component (if applicable):
gdb-7.6.1-78.el7
crash-7.1.2-2.el7
How reproducible:
always
Steps to Reproduce:
1. see above
Actual results:
0x00000000004004f4 <+4>: 66 data16
0x00000000004004f5 <+5>: 0f ae 3f clflush (%rdi)
Expected results:
0x00000000004004f4 <+4>: 66 0f ae 3f clflushopt (%rdi)
Additional info:
See bug 1170846 comment 19 for where the issue was seen with crash
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://rhn.redhat.com/errata/RHBA-2016-2328.html
Description of problem: Please add support to gdb and crash to decode the new CLFLUSHOPT instruction (in Intel Skylake and newer CPUs). Currently gdb shows the 0x66 prefix as a separate instruction, but objdump decodes it correctly: $ echo 'int main(void) { asm volatile("clflushopt (%rdi)"); }' > clflushopt.c $ gcc -g clflushopt.c $ objdump -d a.out | grep clflush 4004f4: 66 0f ae 3f clflushopt (%rdi) $ gdb -q ./a.out Reading symbols from /tmp/clflushopt/a.out...done. (gdb) disas /r main Dump of assembler code for function main: ... 0x00000000004004f4 <+4>: 66 data16 0x00000000004004f5 <+5>: 0f ae 3f clflush (%rdi) Version-Release number of selected component (if applicable): gdb-7.6.1-78.el7 crash-7.1.2-2.el7 How reproducible: always Steps to Reproduce: 1. see above Actual results: 0x00000000004004f4 <+4>: 66 data16 0x00000000004004f5 <+5>: 0f ae 3f clflush (%rdi) Expected results: 0x00000000004004f4 <+4>: 66 0f ae 3f clflushopt (%rdi) Additional info: See bug 1170846 comment 19 for where the issue was seen with crash