linux-kernel - [PATCH 1/1 fyi] tools headers: Sync linux/coresight-pmu.h with the kernel sources

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Date:   Fri, 3 Mar 2023 17:16:57 -0300
From:   arnaldo.melo@...il.com
To:     linux-kernel@...r.kernel.org
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Mike Leach <mike.leach@...aro.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH 1/1 fyi] tools headers: Sync linux/coresight-pmu.h with the
 kernel sources

tldr; Just FYI, I'm carrying this on the perf tools tree.

- Arnaldo

Full explanation:

There used to be no copies, with tools/ code using kernel headers
directly. From time to time tools/perf/ broke due to legitimate kernel
hacking. At some point Linus complained about such direct usage. Then we
adopted the current model.

The way these headers are used in perf are not restricted to just
including them to compile something.

There are sometimes used in scripts that convert defines into string
tables, etc, so some change may break one of these scripts, or new MSRs
may use some different #define pattern, etc.

E.g.:

  $ ls -1 tools/perf/trace/beauty/*.sh | head -5
  tools/perf/trace/beauty/arch_errno_names.sh
  tools/perf/trace/beauty/drm_ioctl.sh
  tools/perf/trace/beauty/fadvise.sh
  tools/perf/trace/beauty/fsconfig.sh
  tools/perf/trace/beauty/fsmount.sh
  $
  $ tools/perf/trace/beauty/fadvise.sh
  static const char *fadvise_advices[] = {
  	[0] = "NORMAL",
  	[1] = "RANDOM",
  	[2] = "SEQUENTIAL",
  	[3] = "WILLNEED",
  	[4] = "DONTNEED",
  	[5] = "NOREUSE",
  };
  $

The tools/perf/check-headers.sh script, part of the tools/ build
process, points out changes in the original files.

So its important not to touch the copies in tools/ when doing changes in
the original kernel headers, that will be done later, when
check-headers.sh inform about the change to the perf tools hackers.

---

To pick up the fixes in:

  206bb3858949b650 ("coresight: trace id: Remove legacy get trace ID function.")
  aa19bb4c35834dd5 ("coresight: events: PERF_RECORD_AUX_OUTPUT_HW_ID used for Trace ID")

That just rebuild perf when CORESIGHT=1 is used in the make command line
to enable linking with the libopencsd.

This addresses this perf build warning:

  Warning: Kernel ABI header at 'tools/include/linux/coresight-pmu.h' differs from latest version at 'include/linux/coresight-pmu.h'
  diff -u tools/include/linux/coresight-pmu.h include/linux/coresight-pmu.h

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Ian Rogers <irogers@...gle.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Mike Leach <mike.leach@...aro.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Suzuki K Poulose <suzuki.poulose@....com>
Link: http://lore.kernel.org/lkml/ZAJUHuvK0yvVAQ95@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/include/linux/coresight-pmu.h | 34 +++++++++++++++++++----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/tools/include/linux/coresight-pmu.h b/tools/include/linux/coresight-pmu.h
index 6c2fd6cc5a983fa4..51ac441a37c3e38f 100644
--- a/tools/include/linux/coresight-pmu.h
+++ b/tools/include/linux/coresight-pmu.h
@@ -7,8 +7,19 @@
 #ifndef _LINUX_CORESIGHT_PMU_H
 #define _LINUX_CORESIGHT_PMU_H
 
+#include <linux/bits.h>
+
 #define CORESIGHT_ETM_PMU_NAME "cs_etm"
-#define CORESIGHT_ETM_PMU_SEED  0x10
+
+/*
+ * The legacy Trace ID system based on fixed calculation from the cpu
+ * number. This has been replaced by drivers using a dynamic allocation
+ * system - but need to retain the legacy algorithm for backward comparibility
+ * in certain situations:-
+ * a) new perf running on older systems that generate the legacy mapping
+ * b) older tools that may not update at the same time as the kernel.
+ */
+#define CORESIGHT_LEGACY_CPU_TRACE_ID(cpu)  (0x10 + (cpu * 2))
 
 /*
  * Below are the definition of bit offsets for perf option, and works as
@@ -34,15 +45,16 @@
 #define ETM4_CFG_BIT_RETSTK	12
 #define ETM4_CFG_BIT_VMID_OPT	15
 
-static inline int coresight_get_trace_id(int cpu)
-{
-	/*
-	 * A trace ID of value 0 is invalid, so let's start at some
-	 * random value that fits in 7 bits and go from there.  Since
-	 * the common convention is to have data trace IDs be I(N) + 1,
-	 * set instruction trace IDs as a function of the CPU number.
-	 */
-	return (CORESIGHT_ETM_PMU_SEED + (cpu * 2));
-}
+/*
+ * Interpretation of the PERF_RECORD_AUX_OUTPUT_HW_ID payload.
+ * Used to associate a CPU with the CoreSight Trace ID.
+ * [07:00] - Trace ID - uses 8 bits to make value easy to read in file.
+ * [59:08] - Unused (SBZ)
+ * [63:60] - Version
+ */
+#define CS_AUX_HW_ID_TRACE_ID_MASK	GENMASK_ULL(7, 0)
+#define CS_AUX_HW_ID_VERSION_MASK	GENMASK_ULL(63, 60)
+
+#define CS_AUX_HW_ID_CURR_VERSION 0
 
 #endif
-- 
2.39.2