perf cs-etm: Output 0 instead of 0xdeadbeef when exception packets are flushed

Normally exception packets don't directly output a branch sample, but
if they're the last record in a buffer then they will. Because they
don't have addresses set we'll see the placeholder value
CS_ETM_INVAL_ADDR (0xdeadbeef) in the output.

Since commit 6035b6804bdf ("perf cs-etm: Support dummy address value for
CS_ETM_TRACE_ON packet") we've used 0 as an externally visible "not set"
address value. For consistency reasons and to not make exceptions look
like an error, change them to use 0 too.

This is particularly visible when doing userspace only tracing because
trace is disabled when jumping to the kernel, causing the flush and then
forcing the last exception packet to be emitted as a branch. With kernel
trace included, there is no flush so exception packets don't generate
samples until the next range packet and they'll pick up the correct
address.

Before:

  $ perf record -e cs_etm//u -- stress -i 1 -t 1
  $ perf script -F comm,ip,addr,flags

  stress   syscall                    ffffb7eedbc0 => deadbeefdeadbeef
  stress   syscall                    ffffb7f14a14 => deadbeefdeadbeef
  stress   syscall                    ffffb7eedbc0 => deadbeefdeadbeef

After:

  stress   syscall                    ffffb7eedbc0 =>                0
  stress   syscall                    ffffb7f14a14 =>                0
  stress   syscall                    ffffb7eedbc0 =>                0

Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: coresight@lists.linaro.org
Cc: gankulkarni@os.amperecomputing.com
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20240722152756.59453-2-james.clark@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions