[PATCH] perf: Use extended syscall error reporting somewhat

[Alexander Shishkin]

Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/perf_event.c |  5 ++++-
 include/linux/perf_event.h       | 14 ++++++++++++++
 kernel/events/core.c             | 17 ++++++++++++++++-
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index f56cf074d0..5e8f2edb2c 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -12,6 +12,8 @@
  *  For licencing details see kernel-base/COPYING
  */
 
+#define EXTERR_MODNAME	"perf/x86"
+
 #include <linux/perf_event.h>
 #include <linux/capability.h>
 #include <linux/notifier.h>
@@ -426,7 +428,8 @@ int x86_setup_perfctr(struct perf_event *event)
 
 		/* BTS is currently only allowed for user-mode. */
 		if (!attr->exclude_kernel)
-			return -EOPNOTSUPP;
+			return perf_err(-EOPNOTSUPP, exclude_kernel,
+					"BTS sampling not allowed for kernel space");
 
 		/* disallow bts if conflicting events are present */
 		if (x86_add_exclusive(x86_lbr_exclusive_lbr))
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2027809433..eb63074012 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -16,6 +16,20 @@
 
 #include <uapi/linux/perf_event.h>
 
+#include <linux/exterr.h>
+
+struct perf_ext_err_site {
+	struct ext_err_site	site;
+	const char		*attr_field;
+};
+
+#define perf_err(__c, __a, __m)						\
+	({ /* make sure it's a real field before stringifying it */	\
+		struct perf_event_attr __x; (void)__x.__a;		\
+		ext_err(perf, __c, __m,					\
+			.attr_field = __stringify(__a));		\
+	})
+
 /*
  * Kernel-internal data types and definitions:
  */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index ae16867670..5523c623c4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9,6 +9,8 @@
  * For licensing details see kernel-base/COPYING
  */
 
+#define EXTERR_MODNAME	"perf"
+
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/cpu.h>
@@ -44,11 +46,24 @@
 #include <linux/compat.h>
 #include <linux/bpf.h>
 #include <linux/filter.h>
+#include <linux/exterr.h>
 
 #include "internal.h"
 
 #include <asm/irq_regs.h>
 
+static char *perf_exterr_format(void *site)
+{
+	struct perf_ext_err_site *psite = site;
+	char *output;
+
+	output = kasprintf(GFP_KERNEL, ",\t\"attr_field\": \"%s\"\n",
+			   psite->attr_field);
+	return output;
+}
+
+DECLARE_EXTERR_DOMAIN(perf, perf_exterr_format);
+
 static struct workqueue_struct *perf_wq;
 
 typedef int (*remote_function_f)(void *);
@@ -8352,7 +8367,7 @@ err_group_fd:
 	fdput(group);
 err_fd:
 	put_unused_fd(event_fd);
-	return err;
+	return ext_err_errno(err);
 }
 
 /**
-- 
2.5.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/