perf annotate: Add support to capture and parse raw instruction in powerpc using dso__data_read_offset utility

Add support to capture and parse raw instruction in powerpc.
Currently, the perf tool infrastructure uses two ways to disassemble
and understand the instruction. One is objdump and other option is
via libcapstone.

Currently, the perf tool infrastructure uses "--no-show-raw-insn" option
with "objdump" while disassemble. Example from powerpc with this option
for an instruction address is:

Snippet from:

  objdump  --start-address=<address> --stop-address=<address>  -d --no-show-raw-insn -C <vmlinux>

  c0000000010224b4:	lwz     r10,0(r9)

This line "lwz r10,0(r9)" is parsed to extract instruction name,
registers names and offset. Also to find whether there is a memory
reference in the operands, "memory_ref_char" field of objdump is used.
For x86, "(" is used as memory_ref_char to tackle instructions of the
form "mov  (%rax), %rcx".

In case of powerpc, not all instructions using "(" are the only memory
instructions. Example, above instruction can also be of extended form (X
form) "lwzx r10,0,r19". Inorder to easy identify the instruction category
and extract the source/target registers, patch adds support to use raw
instruction for powerpc. Approach used is to read the raw instruction
directly from the DSO file using "dso__data_read_offset" utility which
is already implemented in perf infrastructure in "util/dso.c".

Example:

38 01 81 e8     ld      r4,312(r1)

Here "38 01 81 e8" is the raw instruction representation. In powerpc,
this translates to instruction form: "ld RT,DS(RA)" and binary code
as:

   | 58 |  RT  |  RA |      DS       | |
   -------------------------------------
   0    6     11    16              30 31

Function "symbol__disassemble_dso" is updated to read raw instruction
directly from DSO using dso__data_read_offset utility. In case of
above example, this captures:
line:    38 01 81 e8

The above works well when 'perf report' is invoked with only sort keys
for data type ie type and typeoff.

Because there is no instruction level annotation needed if only data
type information is requested for.

For annotating sample, along with type and typeoff sort key, "sym" sort
key is also needed. And by default invoking just "perf report" uses sort
key "sym" that displays the symbol information.

With approach changes in powerpc which first reads DSO for raw
instruction, "perf annotate" and "perf report" + a key breaks since
it doesn't do the instruction level disassembly.

Snippet of result from 'perf report':

  Samples: 1K of event 'mem-loads', 4000 Hz, Event count (approx.): 937238
  do_work  /usr/bin/pmlogger [Percent: local period]
  Percent│        ea230010
         │        3a550010
         │        3a600000

         │        38f60001
         │        39490008
         │        42400438
   51.44 │        81290008
         │        7d485378

Here, raw instruction is displayed in the output instead of human
readable annotated form.

One way to get the appropriate data is to specify "--objdump path", by
which code annotation will be done. But the default behaviour will be
changed. To fix this breakage, check if "sym" sort key is set. If so
fallback and use the libcapstone/objdump way of disassmbling the sample.

With the changes and "perf report"

Samples: 1K of event 'mem-loads', 4000 Hz, Event count (approx.): 937238
do_work  /usr/bin/pmlogger [Percent: local period]
Percent│        ld        r17,16(r3)
       │        addi      r18,r21,16
       │        li        r19,0

       │ 8b0:   rldicl    r10,r10,63,33
       │        addi      r10,r10,1
       │        mtctr     r10
       │      ↓ b         8e4
       │ 8c0:   addi      r7,r22,1
       │        addi      r10,r9,8
       │      ↓ bdz       d00
 51.44 │        lwz       r9,8(r9)
       │        mr        r8,r10
       │        cmpw      r20,r9

Committer notes:

Just add the extern for 'sort_order' in disasm.c so that we don't end up
breaking the build due to this type colision with capstone and libbpf:

  In file included from /usr/include/capstone/capstone.h:325,
                   from /git/perf-6.10.0/tools/perf/util/print_insn.h:23,
                   from builtin-script.c:38:
  /usr/include/capstone/bpf.h:94:14: error: 'bpf_insn' defined as wrong kind of tag
     94 | typedef enum bpf_insn {

I reported this to the bpf mailing list, see one of the links below.

Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Kajol Jain <kjain@linux.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Akanksha J N <akanksha@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Link: https://lore.kernel.org/lkml/20240718084358.72242-6-atrajeev@linux.vnet.ibm.com
Link: https://lore.kernel.org/bpf/ZqOltPk9VQGgJZAA@x1/T/#u
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions