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[PATCH v2 5/6] perf/x86/intel/pt: Use extended error reporting in event initialization

From Alexander Shishkin <alexander.shishkin@linux.intel.com>
Newsgroups linux.kernel
Subject [PATCH v2 5/6] perf/x86/intel/pt: Use extended error reporting in event initialization
Date 2015-08-24 16:40 +0200
Message-ID <q114K-23E-5@gated-at.bofh.it> (permalink)
References <q114K-23E-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Event attribute validation is one of the biggest sources of EINVALs around
perf_event_open() syscall. This patch annotates error checks with extended
error reporting macros to provide the user with more details on what they
are doing wrong.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
 arch/x86/kernel/cpu/perf_event_intel_pt.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c b/arch/x86/kernel/cpu/perf_event_intel_pt.c
index 4216928344..9a09c89928 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_pt.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
@@ -18,6 +18,8 @@
 
 #undef DEBUG
 
+#define PERF_MODNAME	"perf/x86/intel/pt"
+
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/types.h>
@@ -198,29 +200,29 @@ fail:
 			RTIT_CTL_CYC_PSB	| \
 			RTIT_CTL_MTC)
 
-static bool pt_event_valid(struct perf_event *event)
+static int pt_event_valid(struct perf_event *event)
 {
 	u64 config = event->attr.config;
 	u64 allowed, requested;
 
 	if ((config & PT_CONFIG_MASK) != config)
-		return false;
+		return perf_err(-EINVAL, "PT config: disallowed bits");
 
 	if (config & RTIT_CTL_CYC_PSB) {
 		if (!pt_cap_get(PT_CAP_psb_cyc))
-			return false;
+			return perf_err(-EINVAL, "PT config: PSB/CYC not supported");
 
 		allowed = pt_cap_get(PT_CAP_psb_periods);
 		requested = (config & RTIT_CTL_PSB_FREQ) >>
 			RTIT_CTL_PSB_FREQ_OFFSET;
 		if (requested && (!(allowed & BIT(requested))))
-			return false;
+			return perf_err(-EINVAL, "PT config: unsupported PSB period");
 
 		allowed = pt_cap_get(PT_CAP_cycle_thresholds);
 		requested = (config & RTIT_CTL_CYC_THRESH) >>
 			RTIT_CTL_CYC_THRESH_OFFSET;
 		if (requested && (!(allowed & BIT(requested))))
-			return false;
+			return perf_err(-EINVAL, "PT config: unsupported CYC threshold");
 	}
 
 	if (config & RTIT_CTL_MTC) {
@@ -232,20 +234,20 @@ static bool pt_event_valid(struct perf_event *event)
 		 * CPUID is 0 will #GP, so better safe than sorry.
 		 */
 		if (!pt_cap_get(PT_CAP_mtc))
-			return false;
+			return perf_err(-EINVAL, "PT config: MTC not supported");
 
 		allowed = pt_cap_get(PT_CAP_mtc_periods);
 		if (!allowed)
-			return false;
+			return perf_err(-EINVAL, "PT config: MTC periods not supported");
 
 		requested = (config & RTIT_CTL_MTC_RANGE) >>
 			RTIT_CTL_MTC_RANGE_OFFSET;
 
 		if (!(allowed & BIT(requested)))
-			return false;
+			return perf_err(-EINVAL, "PT config: unsupported MTC period");
 	}
 
-	return true;
+	return 0;
 }
 
 /*
@@ -1111,14 +1113,17 @@ static void pt_event_destroy(struct perf_event *event)
 
 static int pt_event_init(struct perf_event *event)
 {
+	int err;
+
 	if (event->attr.type != pt_pmu.pmu.type)
 		return -ENOENT;
 
-	if (!pt_event_valid(event))
-		return -EINVAL;
+	err = pt_event_valid(event);
+	if (err)
+		return err;
 
 	if (x86_add_exclusive(x86_lbr_exclusive_pt))
-		return -EBUSY;
+		return perf_err(-EBUSY, "PT conflicts with active events");
 
 	event->destroy = pt_event_destroy;
 
-- 
2.5.0

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Thread

[PATCH v2 0/6] perf: Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-24 16:40 +0200
  [PATCH v2 5/6] perf/x86/intel/pt: Use extended error reporting in event initialization Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-24 16:40 +0200
  [PATCH v2 6/6] perf/x86/intel/bts: Use extended error reporting in event initialization Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-24 16:40 +0200
  [PATCH v2 1/6] perf: Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-24 16:40 +0200
    Re: [PATCH v2 1/6] perf: Introduce extended syscall error reporting Andy Shevchenko <andy.shevchenko@gmail.com> - 2015-08-31 20:50 +0200
      Re: [PATCH v2 1/6] perf: Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-09-01 08:40 +0200
  [PATCH v2 3/6] perf: Annotate some of the error codes with perf_err() Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-24 16:40 +0200
  [PATCH v2 2/6] perf: Add file name and line number to perf extended error reports Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-24 16:40 +0200
  [PATCH v2 4/6] perf/x86: Annotate some of the error codes with perf_err() Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-24 16:40 +0200
  Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-25 10:30 +0200
  Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Johannes Berg <johannes@sipsolutions.net> - 2015-08-25 11:00 +0200
    Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-25 11:10 +0200
      Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-25 11:20 +0200
        Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Johannes Berg <johannes@sipsolutions.net> - 2015-08-25 11:40 +0200
          Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-25 12:10 +0200
            Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Johannes Berg <johannes@sipsolutions.net> - 2015-08-25 12:30 +0200
              Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-26 07:00 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Johannes Berg <johannes@sipsolutions.net> - 2015-08-26 09:10 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-26 09:30 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-26 19:00 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-08-26 23:00 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Andrew Morton <akpm@linux-foundation.org> - 2015-08-26 20:50 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Peter Zijlstra <peterz@infradead.org> - 2015-08-26 22:10 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Andrew Morton <akpm@linux-foundation.org> - 2015-08-26 22:30 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error  reporting Vince Weaver <vince@deater.net> - 2015-08-26 23:00 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Andrew Morton <akpm@linux-foundation.org> - 2015-08-26 23:00 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error  reporting Vince Weaver <vince@deater.net> - 2015-08-26 23:20 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-28 12:10 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Arnaldo Carvalho de Melo <acme@infradead.org> - 2015-08-26 23:10 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-26 09:30 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Johannes Berg <johannes@sipsolutions.net> - 2015-08-26 09:40 +0200
                Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Ingo Molnar <mingo@kernel.org> - 2015-08-26 09:10 +0200
        Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting Alexander Shishkin <alexander.shishkin@linux.intel.com> - 2015-08-26 13:40 +0200

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