[PATCH] perf pmu: Create x86 specific perf_pmu__valid_suffix

[PATCH] perf pmu: Create x86 specific perf_pmu__valid_suffix

[Jin Yao]

The commit c47a5599eda3 ("perf tools: Fix pattern matching for same
substring in different PMU type") breaks arm64 system because it
assumes the first token must be followed by a '_', but it is
possibly a numeric on arm64.

For example, perf_pmu__valid_suffix("hisi_sccl3_l3c7", "hisi_sccl")
fails. "hisi_sccl3_l3c7" is pmu name and "hisi_sccl" is token.
"hisi_sccl" is followed by a digit but not followed by a '_'
('3' in this example).

Since the PMU alias format on arm64 has difference than the format
on x86. Create a x86 specific perf_pmu__valid_suffix. For other arch,
the weak function always returns true to keep original behavior
unchanged.

Fixes: c47a5599eda3 ("perf tools: Fix pattern matching for same substring in different PMU type")
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Reported-by: John Garry <john.garry@huawei.com>
---
 tools/perf/arch/x86/util/pmu.c | 22 ++++++++++++++++++++++
 tools/perf/util/pmu.c          | 27 ++++++---------------------
 tools/perf/util/pmu.h          |  1 +
 3 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
index d48d608517fd..519da0811308 100644
--- a/tools/perf/arch/x86/util/pmu.c
+++ b/tools/perf/arch/x86/util/pmu.c
@@ -3,6 +3,7 @@
 
 #include <linux/stddef.h>
 #include <linux/perf_event.h>
+#include <linux/ctype.h>
 
 #include "../../../util/intel-pt.h"
 #include "../../../util/intel-bts.h"
@@ -18,3 +19,24 @@ struct perf_event_attr *perf_pmu__get_default_config(struct perf_pmu *pmu __mayb
 #endif
 	return NULL;
 }
+
+bool perf_pmu__valid_suffix(char *pmu_name, char *tok)
+{
+	char *p;
+
+	if (strncmp(pmu_name, tok, strlen(tok)))
+		return false;
+
+	p = pmu_name + strlen(tok);
+	if (*p == 0)
+		return true;
+
+	if (*p != '_')
+		return false;
+
+	++p;
+	if (*p == 0 || !isdigit(*p))
+		return false;
+
+	return true;
+}
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 44b90d638ad5..a671b16f2d3e 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -742,27 +742,6 @@ struct pmu_events_map *__weak pmu_events_map__find(void)
 	return perf_pmu__find_map(NULL);
 }
 
-static bool perf_pmu__valid_suffix(char *pmu_name, char *tok)
-{
-	char *p;
-
-	if (strncmp(pmu_name, tok, strlen(tok)))
-		return false;
-
-	p = pmu_name + strlen(tok);
-	if (*p == 0)
-		return true;
-
-	if (*p != '_')
-		return false;
-
-	++p;
-	if (*p == 0 || !isdigit(*p))
-		return false;
-
-	return true;
-}
-
 bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
 {
 	char *tmp = NULL, *tok, *str;
@@ -1906,3 +1885,9 @@ int perf_pmu__match(char *pattern, char *name, char *tok)
 
 	return 0;
 }
+
+bool __weak perf_pmu__valid_suffix(char *pmu_name __maybe_unused,
+				   char *tok __maybe_unused)
+{
+	return true;
+}
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 926da483a141..901812987b79 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -134,5 +134,6 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,
 
 bool perf_pmu__has_hybrid(void);
 int perf_pmu__match(char *pattern, char *name, char *tok);
+bool perf_pmu__valid_suffix(char *pmu_name, char *tok);
 
 #endif /* __PMU_H */
-- 
2.17.1

Re: [PATCH] perf pmu: Create x86 specific perf_pmu__valid_suffix

[John Garry]

On 20/07/2021 09:20, Jin Yao wrote:
> The commit c47a5599eda3 ("perf tools: Fix pattern matching for same
> substring in different PMU type") breaks arm64 system because it
> assumes the first token must be followed by a '_', but it is
> possibly a numeric on arm64.

I wouldn't just say arm64. The core code should support matching 
multiple tokens, but it just so happens that only arm64 uses it.

> 
> For example, perf_pmu__valid_suffix("hisi_sccl3_l3c7", "hisi_sccl")
> fails. "hisi_sccl3_l3c7" is pmu name and "hisi_sccl" is token.
> "hisi_sccl" is followed by a digit but not followed by a '_'
> ('3' in this example).
> 
> Since the PMU alias format on arm64 has difference than the format
> on x86. Create a x86 specific perf_pmu__valid_suffix. For other arch,
> the weak function always returns true to keep original behavior
> unchanged.
> 
> Fixes: c47a5599eda3 ("perf tools: Fix pattern matching for same substring in different PMU type")
> Signed-off-by: Jin Yao<yao.jin@linux.intel.com>
> Reported-by: John Garry<john.garry@huawei.com>
> ---

I tend not to agree with this solution. Let's not make it x86 vs non-x86 
problem. Indeed, if we continue to support custom PMU alias matching 
per-arch, then it becomes a maintenance burden.

So this change fixes my initial problem:

-----8<------

 From bbc9c7bf65c9cea756f0716dd717e9cfc767ba39 Mon Sep 17 00:00:00 2001
From: John Garry <john.garry@huawei.com>
Date: Tue, 20 Jul 2021 09:48:22 +0100
Subject: [PATCH] perf pmu: Only check valid suffix for final token

Since commit 730670b1d108 ("perf pmu: Support more complex PMU event
aliasing"), matching multiple alias tokens has been supported.

However, commit c47a5599eda32 ("perf tools: Fix pattern matching for 
same substring in different PMU type"), ignored the possibility of 
multiple tokens, and assumed that we can only match on valid suffix and 
a single token.

Fix multiple token support by only checking valid suffix from final token.

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 44b90d638ad5..6de2275b2ae2 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -789,12 +789,17 @@ bool pmu_uncore_alias_match(const char *pmu_name, 
const char *name)
  	 *	    match "socket" in "socketX_pmunameY" and then "pmuname" in
  	 *	    "pmunameY".
  	 */
-	for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {
+	for (; ; ) {
+		char *next_tok = strtok_r(NULL, ",", &tmp);
  		name = strstr(name, tok);
-		if (!name || !perf_pmu__valid_suffix((char *)name, tok)) {
+		if (!name || (!perf_pmu__valid_suffix((char *)name, tok) && !next_tok)) {
  			res = false;
  			goto out;
  		}
+		if (!next_tok)
+			break;
+		name += strlen(tok);
+		tok = next_tok;
  	}

  	res = true;
-- 
2.26.2

----->8------

Please check it.

I need to check the other place perf_pmu__valid_suffix() is referenced 
(perf_pmu__match()) to see if anything is broken there.

Thanks,
John