Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1214041
| From | Alexander Shishkin <alexander.shishkin@linux.intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2 0/6] perf: Introduce extended syscall error reporting |
| Date | 2015-08-26 19:00 +0200 |
| Message-ID | <q1Mdk-38r-11@gated-at.bofh.it> (permalink) |
| References | (6 earlier) <q1AYx-3Q5-1@gated-at.bofh.it> <q1D0l-71b-9@gated-at.bofh.it> <q1D0l-71b-7@gated-at.bofh.it> <q1DjI-7nv-11@gated-at.bofh.it> <q1DjI-7nv-9@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Ingo Molnar <mingo@kernel.org> writes:
> * Ingo Molnar <mingo@kernel.org> wrote:
>
>> ... but back then I didn't feel like complicating an error recovery ABI for the
>> needs of the 1%, robust error handling is all about simplicity: if it's not
>> simple, tools won't use it.
>
> And note that it needs to be 'simple' in two places for usage to grow naturally:
>
> - the usage site in the kernel
> - the tooling side that recovers the information.
>
> That's why I think that such a form:
>
> return err_str(-EINVAL, "x86/perf: CPU does not support precise sampling");
>
> is obviously simple on the kernel side as it returns -EINVAL, and is very simple
> on the tooling side as well, if we are allowed to extend prctl().
So I hacked stuff a bit [1] to accomodate some of the above
ideas. The below diff shows how these ideas integrate with perf. The
rest is in my github tree.
- this exterr implementation allows its users to add arbitrary
information to the call site structures and also pretty print them on
the way out; in the example, perf stores perf_event_attr field name
that is the source of trouble; it's a string rather than offsetof(),
because half of our event attribute is a bit field;
- the "way out" doesn't have to be syscall return path (although in the
example it is);
- userspace can fetch the extended error reports via prctl() like you
suggested above;
- error codes are still passed around in the [-EXT_ERRNO..-MAX_ERRNO]
range until they are passed to userspace (which is where ext_err_code()
converts them back to traditional errno.h values).
# perf record -e branches -c1 ls
kernel says (0/95): {
"file": "/home/ash/work/linux/arch/x86/kernel/cpu/perf_event.c",
"line": 432,
"code": -95,
"module": "perf/x86",
"message": "BTS sampling not allowed for kernel space"
, "attr_field": "exclude_kernel"
}
Error:
No hardware sampling interrupt available.
No APIC? If so then you can boot the kernel with the "lapic" boot parameter to force-enable it.
#
[1] https://github.com/virtuoso/linux-perf/commits/exterr
From 1338fe417223cc1d8bc7588d95c6a913993d966f Mon Sep 17 00:00:00 2001
From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Date: Wed, 26 Aug 2015 18:36:14 +0300
Subject: [PATCH] perf: Use extended syscall error reporting somewhat
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
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@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll 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
csiph-web