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The x86 instruction decoder is used not only for decoding kernel
instructions. It is also used by perf uprobes (user space probes) and by
perf tools Intel Processor Trace decoding. Consequently, it needs to
support instructions executed by user space also.
Opcode 0x68 PUSH instruction is currently defined as 64-bit operand size
only i.e. (d64). That was based on Intel SDM Opcode Map. However that is
contradicted by the Instruction Set Reference section for PUSH in the
same manual.
Remove 64-bit operand size only annotation from opcode 0x68 PUSH
instruction.
Example:
$ cat pushw.s
.global _start
.text
_start:
pushw $0x1234
mov $0x1,%eax # system call number (sys_exit)
int $0x80
$ as -o pushw.o pushw.s
$ ld -s -o pushw pushw.o
$ objdump -d pushw | tail -4
0000000000401000 <.text>:
401000: 66 68 34 12 pushw $0x1234
401004: b8 01 00 00 00 mov $0x1,%eax
401009: cd 80 int $0x80
$ perf record -e intel_pt//u ./pushw
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.014 MB perf.data ]
Before:
$ perf script --insn-trace=disasm
Warning:
1 instruction trace errors
pushw 10349 [000] 10586.869237014: 401000 [unknown] (/home/ahunter/git/misc/rtit-tests/pushw) pushw $0x1234
pushw 10349 [000] 10586.869237014: 401006 [unknown] (/home/ahunter/git/misc/rtit-tests/pushw) addb %al, (%rax)
pushw 10349 [000] 10586.869237014: 401008 [unknown] (/home/ahunter/git/misc/rtit-tests/pushw) addb %cl, %ch
pushw 10349 [000] 10586.869237014: 40100a [unknown] (/home/ahunter/git/misc/rtit-tests/pushw) addb $0x2e, (%rax)
instruction trace error type 1 time 10586.869237224 cpu 0 pid 10349 tid 10349 ip 0x40100d code 6: Trace doesn't match instruction
After:
$ perf script --insn-trace=disasm
pushw 10349 [000] 10586.869237014: 401000 [unknown] (./pushw) pushw $0x1234
pushw 10349 [000] 10586.869237014: 401004 [unknown] (./pushw) movl $1, %eax
Fixes: eb13296cfa ("x86: Instruction decoder API")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20240502105853.5338-3-adrian.hunter@intel.com
59162e0c11