linux-kernel - [PATCH v2 11/13] perf tools: improve IBS error handling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20211111084415.663951-12-eranian@google.com>
Date:   Thu, 11 Nov 2021 00:44:13 -0800
From:   Stephane Eranian <eranian@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     peterz@...radead.org, kim.phillips@....com, acme@...hat.com,
        jolsa@...hat.com, songliubraving@...com, mpe@...erman.id.au,
        maddy@...ux.ibm.com
Subject: [PATCH v2 11/13] perf tools: improve IBS error handling

From: Kim Phillips <kim.phillips@....com>

This patch improves the error message returned on failed perf_event_open() on
AMD when using IBS.

Signed-off-by: Kim Phillips <kim.phillips@....com>
---
 tools/perf/util/evsel.c | 42 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index dbfeceb2546c..1b24b3000d66 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2743,12 +2743,52 @@ static bool find_process(const char *name)
 	return ret ? false : true;
 }
 
+static bool is_amd;
+
+static char *fgrep(FILE *inf, const char *str)
+{
+	char line[256];
+	int slen = strlen(str);
+
+	while (!feof(inf)) {
+		if (!fgets(line, 256, inf))
+			break;
+		if (strncmp(line, str, slen))
+			continue;
+
+		return strdup(line);
+	}
+
+	return NULL;
+}
+
+static void detect_amd(void)
+{
+	FILE *inf = fopen("/proc/cpuinfo", "r");
+	char *res;
+
+	if (!inf)
+		return;
+
+	res = fgrep(inf, "vendor_id");
+
+	if (res) {
+		char *s = strchr(res, ':');
+
+		is_amd = s && !strcmp(s, ": AuthenticAMD\n");
+		free(res);
+	}
+	fclose(inf);
+}
+
 int evsel__open_strerror(struct evsel *evsel, struct target *target,
 			 int err, char *msg, size_t size)
 {
 	char sbuf[STRERR_BUFSIZE];
 	int printed = 0, enforced = 0;
 
+	detect_amd();
+
 	switch (err) {
 	case EPERM:
 	case EACCES:
@@ -2841,6 +2881,8 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
 			return scnprintf(msg, size, "wrong clockid (%d).", clockid);
 		if (perf_missing_features.aux_output)
 			return scnprintf(msg, size, "The 'aux_output' feature is not supported, update the kernel.");
+		if (is_amd && (evsel->core.attr.precise_ip || !strncmp(evsel->pmu_name, "ibs", 3)) && (evsel->core.attr.exclude_kernel))
+			return scnprintf(msg, size, "AMD IBS can't exclude kernel events.  Try running at a higher privilege level.");
 		break;
 	case ENODATA:
 		return scnprintf(msg, size, "Cannot collect data source with the load latency event alone. "
-- 
2.34.0.rc0.344.g81b53c2807-goog