[V3,0/2] Fix Coresight instruction synthesis logic

Message

Tanmay Jagdale March 27, 2025, 11:11 a.m. UTC

When we use perf to catpure Coresight trace and generate instruction
trace using 'perf script', we get the following output:

# perf record -e cs_etm/@tmc_etr0/ -C 9 taskset -c 9 sleep 1
# perf script --itrace=i1ns --ns -Fcomm,tid,pid,time,cpu,event,ip,sym,addr,symoff,flags,callindent
..
 perf  9024/9024  [009]  2690.650470551:      instructions:   call                                 0 ffffb305591aed54 coresight_timeout+0x28
 perf  9024/9024  [009]  2690.650470551:      instructions:   call                                 0 ffffb305591aed58 coresight_timeout+0x2c
 perf  9024/9024  [009]  2690.650470551:      instructions:   call                                 0 ffffb305591aed5c coresight_timeout+0x30
 perf  9024/9024  [009]  2690.650470551:      instructions:   call                                 0 ffffb305591aed60 coresight_timeout+0x34
 perf  9024/9024  [009]  2690.650470551:      instructions:   jmp                                  0 ffffb305591aed7c coresight_timeout+0x50
 perf  9024/9024  [009]  2690.650470551:      instructions:   jmp                                  0 ffffb305591aed80 coresight_timeout+0x54
 perf  9024/9024  [009]  2690.650470551:      instructions:   jmp                                  0 ffffb305591aed84 coresight_timeout+0x58
 perf  9024/9024  [009]  2690.650470552:      instructions:   jcc                                  0 ffffb305591aede4 coresight_timeout+0xb8
 perf  9024/9024  [009]  2690.650470552:      instructions:   jcc                                  0 ffffb305591aede8 coresight_timeout+0xbc
 perf  9024/9024  [009]  2690.650470552:      instructions:   jcc                                  0 ffffb305591aedec coresight_timeout+0xc0
 perf  9024/9024  [009]  2690.650470552:      instructions:   jcc                                  0 ffffb305591aedf0 coresight_timeout+0xc4
 perf  9024/9024  [009]  2690.650470557:      instructions:   call                                 0 ffffb305591bccec ete_sysreg_read+0x0
 perf  9024/9024  [009]  2690.650470557:      instructions:   call                                 0 ffffb305591bccf0 ete_sysreg_read+0x4
 perf  9024/9024  [009]  2690.650470557:      instructions:   call                                 0 ffffb305591bccf4 ete_sysreg_read+0x8
 perf  9024/9024  [009]  2690.650470557:      instructions:   call                                 0 ffffb305591bccf8 ete_sysreg_read+0xc
 perf  9024/9024  [009]  2690.650470557:      instructions:   call                                 0 ffffb305591bccfc ete_sysreg_read+0x10
 perf  9024/9024  [009]  2690.650470557:      instructions:   call                                 0 ffffb305591bcd00 ete_sysreg_read+0x14

This output has the following issues:
1. Non-branch instructions have mnemonics of branch instructions (Column 6)
2. Branch target address is missing (Column 7)

This patch fixes these issues by changing the logic of instruction syntehsis
for the Coresight trace queues.

Output after applying the patch:
 ...
 perf  6111/6111  [008]   457.332794461:      instructions:                                        0 ffffb305591aed54 coresight_timeout+0x28
 perf  6111/6111  [008]   457.332794461:      instructions:                                        0 ffffb305591aed58 coresight_timeout+0x2c
 perf  6111/6111  [008]   457.332794461:      instructions:                                        0 ffffb305591aed5c coresight_timeout+0x30
 perf  6111/6111  [008]   457.332794461:      instructions:   jmp                   ffffb305591aed7c ffffb305591aed60 coresight_timeout+0x34
 perf  6111/6111  [008]   457.332794461:      instructions:                                        0 ffffb305591aed7c coresight_timeout+0x50
 perf  6111/6111  [008]   457.332794461:      instructions:                                        0 ffffb305591aed80 coresight_timeout+0x54
 perf  6111/6111  [008]   457.332794461:      instructions:   jcc                   ffffb305591aede4 ffffb305591aed84 coresight_timeout+0x58
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591aede4 coresight_timeout+0xb8
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591aede8 coresight_timeout+0xbc
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591aedec coresight_timeout+0xc0
 perf  6111/6111  [008]   457.332794462:      instructions:   call                  ffffb305591bccec ffffb305591aedf0 coresight_timeout+0xc4
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591bccec ete_sysreg_read+0x0
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591bccf0 ete_sysreg_read+0x4
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591bccf4 ete_sysreg_read+0x8
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591bccf8 ete_sysreg_read+0xc
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591bccfc ete_sysreg_read+0x10
 perf  6111/6111  [008]   457.332794462:      instructions:                                        0 ffffb305591bcd00 ete_sysreg_read+0x14

Changes in V3
  - Rebased to latest coresight-next branch
  - Added Reviewed-by tags from V2 [2]

Changes in V2
  - Updated commit message of Patch 1
  - As discussed in the previous version [1], there were differences in instruction
    trace output before and after the patch. The timestamps for the instructions
    were not in sync. Added a patch 2 which fixes this issue.

Changes in V1
  - https://lkml.org/lkml/2023/6/23/912

[1] https://lkml.org/lkml/2023/6/28/506
[2] https://lore.kernel.org/lkml/[e-mail]/

Tanmay Jagdale (2):
  perf: cs-etm: Fixes in instruction sample synthesis
  perf: cs-etm: Store previous timestamp in packet queue

 tools/perf/util/cs-etm.c | 49 +++++++++++++++++++++++++++++++---------
 tools/perf/util/cs-etm.h |  1 +
 2 files changed, 39 insertions(+), 11 deletions(-)