linux-kernel - [PATCH v2] perf headers: fix processing of pmu

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Message-Id: <20200609193050.241972-1-eranian@google.com>
Date:   Tue,  9 Jun 2020 12:30:50 -0700
From:   Stephane Eranian <eranian@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     acme@...hat.com, jolsa@...hat.com, peterz@...radead.org,
        mingo@...e.hu, irogers@...gle.com
Subject: [PATCH v2] perf headers: fix processing of pmu_mappings

This patch changes the handling of the env->pmu_mappings string.
It transforms the string from a \0 separated list of value:name pairs
into a space separated list of value:name pairs. This makes it much simpler
to parse looking for a particular value or name.

This version also updates print_pmu_mappings() to handle the new space
separator.

Before: printf(env->pmu_mappings);
14:amd_iommu_1

After: printf(env->pmu_mappings);
14:amd_iommu_1 7:uprobe 5:breakpoint 10:amd_l3 19:amd_iommu_6 8:power 4:cpu 17:amd_iommu_4 15:amd_iommu_2 1:software 6:kprobe 13:amd_iommu_0 9:amd_df 20:amd_iommu_7 18:amd_iommu_5 2:tracepoint 21:msr 12:ibs_op 16:amd_iommu_3 11:ibs_fetch

Signed-off-by: Stephane Eranian <eranian@...gle.com>
---
 tools/perf/util/header.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 31a7f278036c..3649c0e1740b 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1470,10 +1470,19 @@ static void print_pmu_mappings(struct feat_fd *ff, FILE *fp)
 			goto error;
 
 		str = tmp + 1;
+
+		tmp = strchr(str, ' ');
+		if (tmp)
+			*tmp = '\0';
+
 		fprintf(fp, "%s%s = %" PRIu32, delimiter, str, type);
 
 		delimiter = ", ";
-		str += strlen(str) + 1;
+
+		if (tmp) {
+			*tmp = ' ';
+			str = tmp + 1;
+		}
 		pmu_num--;
 	}
 
@@ -1956,13 +1965,15 @@ static int process_numa_topology(struct feat_fd *ff, void *data __maybe_unused)
 static int process_pmu_mappings(struct feat_fd *ff, void *data __maybe_unused)
 {
 	char *name;
-	u32 pmu_num;
+	u32 pmu_num, o_num;
 	u32 type;
 	struct strbuf sb;
 
 	if (do_read_u32(ff, &pmu_num))
 		return -1;
 
+	o_num = pmu_num;
+
 	if (!pmu_num) {
 		pr_debug("pmu mappings not available\n");
 		return 0;
@@ -1980,10 +1991,11 @@ static int process_pmu_mappings(struct feat_fd *ff, void *data __maybe_unused)
 		if (!name)
 			goto error;
 
-		if (strbuf_addf(&sb, "%u:%s", type, name) < 0)
+		/* add proper spacing between entries */
+		if (pmu_num < o_num && strbuf_add(&sb, " ", 1) < 0)
 			goto error;
-		/* include a NULL character at the end */
-		if (strbuf_add(&sb, "", 1) < 0)
+
+		if (strbuf_addf(&sb, "%u:%s", type, name) < 0)
 			goto error;
 
 		if (!strcmp(name, "msr"))
@@ -1992,6 +2004,9 @@ static int process_pmu_mappings(struct feat_fd *ff, void *data __maybe_unused)
 		free(name);
 		pmu_num--;
 	}
+	/* include a NULL character at the end */
+	if (strbuf_add(&sb, "", 1) < 0)
+		goto error;
 	ff->ph->env.pmu_mappings = strbuf_detach(&sb, NULL);
 	return 0;
 
-- 
2.27.0.278.ge193c7cf3a9-goog