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[PATCH 02/10] x86/insn: Fix PUSH instruction in x86 instruction decoder opcode map

Adrian Hunter posted 10 patches 1 year, 7 months ago
[PATCH 02/10] x86/insn: Fix PUSH instruction in x86 instruction decoder opcode map
Posted by Adrian Hunter 1 year, 7 months ago 
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: eb13296cfaf6 ("x86: Instruction decoder API")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 arch/x86/lib/x86-opcode-map.txt       | 2 +-
 tools/arch/x86/lib/x86-opcode-map.txt | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/lib/x86-opcode-map.txt b/arch/x86/lib/x86-opcode-map.txt
index c94988d5130d..4ea2e6adb477 100644
--- a/arch/x86/lib/x86-opcode-map.txt
+++ b/arch/x86/lib/x86-opcode-map.txt
@@ -148,7 +148,7 @@ AVXcode:
 65: SEG=GS (Prefix)
 66: Operand-Size (Prefix)
 67: Address-Size (Prefix)
-68: PUSH Iz (d64)
+68: PUSH Iz
 69: IMUL Gv,Ev,Iz
 6a: PUSH Ib (d64)
 6b: IMUL Gv,Ev,Ib
diff --git a/tools/arch/x86/lib/x86-opcode-map.txt b/tools/arch/x86/lib/x86-opcode-map.txt
index c94988d5130d..4ea2e6adb477 100644
--- a/tools/arch/x86/lib/x86-opcode-map.txt
+++ b/tools/arch/x86/lib/x86-opcode-map.txt
@@ -148,7 +148,7 @@ AVXcode:
 65: SEG=GS (Prefix)
 66: Operand-Size (Prefix)
 67: Address-Size (Prefix)
-68: PUSH Iz (d64)
+68: PUSH Iz
 69: IMUL Gv,Ev,Iz
 6a: PUSH Ib (d64)
 6b: IMUL Gv,Ev,Ib
-- 
2.34.1
Re: [PATCH 02/10] x86/insn: Fix PUSH instruction in x86 instruction decoder opcode map
Posted by Arnaldo Carvalho de Melo 1 year, 7 months ago 
On Thu, May 02, 2024 at 01:58:45PM +0300, Adrian Hunter wrote:
> 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.

I wonder if we should do it this way, i.e. updating both tools/ and
kernel source code in the same patch.

I think the best is to update the kernel bits, then, after that is
merged, do the tooling part.

To avoid possible, yet unlikely, clashes in linux-next, for instance.

- Arnaldo
 
> 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: eb13296cfaf6 ("x86: Instruction decoder API")
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
>  arch/x86/lib/x86-opcode-map.txt       | 2 +-
>  tools/arch/x86/lib/x86-opcode-map.txt | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/lib/x86-opcode-map.txt b/arch/x86/lib/x86-opcode-map.txt
> index c94988d5130d..4ea2e6adb477 100644
> --- a/arch/x86/lib/x86-opcode-map.txt
> +++ b/arch/x86/lib/x86-opcode-map.txt
> @@ -148,7 +148,7 @@ AVXcode:
>  65: SEG=GS (Prefix)
>  66: Operand-Size (Prefix)
>  67: Address-Size (Prefix)
> -68: PUSH Iz (d64)
> +68: PUSH Iz
>  69: IMUL Gv,Ev,Iz
>  6a: PUSH Ib (d64)
>  6b: IMUL Gv,Ev,Ib
> diff --git a/tools/arch/x86/lib/x86-opcode-map.txt b/tools/arch/x86/lib/x86-opcode-map.txt
> index c94988d5130d..4ea2e6adb477 100644
> --- a/tools/arch/x86/lib/x86-opcode-map.txt
> +++ b/tools/arch/x86/lib/x86-opcode-map.txt
> @@ -148,7 +148,7 @@ AVXcode:
>  65: SEG=GS (Prefix)
>  66: Operand-Size (Prefix)
>  67: Address-Size (Prefix)
> -68: PUSH Iz (d64)
> +68: PUSH Iz
>  69: IMUL Gv,Ev,Iz
>  6a: PUSH Ib (d64)
>  6b: IMUL Gv,Ev,Ib
> -- 
> 2.34.1
Re: [PATCH 02/10] x86/insn: Fix PUSH instruction in x86 instruction decoder opcode map
Posted by Adrian Hunter 1 year, 7 months ago 
On 2/05/24 16:41, Arnaldo Carvalho de Melo wrote:
> On Thu, May 02, 2024 at 01:58:45PM +0300, Adrian Hunter wrote:
>> 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.
> 
> I wonder if we should do it this way, i.e. updating both tools/ and
> kernel source code in the same patch.
> 
> I think the best is to update the kernel bits, then, after that is
> merged, do the tooling part.

For objtool purposes, it might be better to do both at the same time.

> 
> To avoid possible, yet unlikely, clashes in linux-next, for instance.

Always gonna find out about clashes at some point.
[tip: perf/core] x86/insn: Fix PUSH instruction in x86 instruction decoder opcode map
Posted by tip-bot2 for Adrian Hunter 1 year, 7 months ago 
The following commit has been merged into the perf/core branch of tip:

Commit-ID:     59162e0c11d7257cde15f907d19fefe26da66692
Gitweb:        https://git.kernel.org/tip/59162e0c11d7257cde15f907d19fefe26da66692
Author:        Adrian Hunter <adrian.hunter@intel.com>
AuthorDate:    Thu, 02 May 2024 13:58:45 +03:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Thu, 02 May 2024 13:13:41 +02:00

x86/insn: Fix PUSH instruction in x86 instruction decoder opcode map

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: eb13296cfaf6 ("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
---
 arch/x86/lib/x86-opcode-map.txt       | 2 +-
 tools/arch/x86/lib/x86-opcode-map.txt | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/lib/x86-opcode-map.txt b/arch/x86/lib/x86-opcode-map.txt
index c94988d..4ea2e6a 100644
--- a/arch/x86/lib/x86-opcode-map.txt
+++ b/arch/x86/lib/x86-opcode-map.txt
@@ -148,7 +148,7 @@ AVXcode:
 65: SEG=GS (Prefix)
 66: Operand-Size (Prefix)
 67: Address-Size (Prefix)
-68: PUSH Iz (d64)
+68: PUSH Iz
 69: IMUL Gv,Ev,Iz
 6a: PUSH Ib (d64)
 6b: IMUL Gv,Ev,Ib
diff --git a/tools/arch/x86/lib/x86-opcode-map.txt b/tools/arch/x86/lib/x86-opcode-map.txt
index c94988d..4ea2e6a 100644
--- a/tools/arch/x86/lib/x86-opcode-map.txt
+++ b/tools/arch/x86/lib/x86-opcode-map.txt
@@ -148,7 +148,7 @@ AVXcode:
 65: SEG=GS (Prefix)
 66: Operand-Size (Prefix)
 67: Address-Size (Prefix)
-68: PUSH Iz (d64)
+68: PUSH Iz
 69: IMUL Gv,Ev,Iz
 6a: PUSH Ib (d64)
 6b: IMUL Gv,Ev,Ib

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