[PATCH] perf: Fix sigbus with perf-top

[PATCH] perf: Fix sigbus with perf-top

[David Ahern]

perf-top is terminating due to SIGBUS on sparc64. git bisect points to:

    commit 82396986032915c1572bfb74b224fcc2e4e8ba7c
    Author: Arnaldo Carvalho de Melo <acme@redhat.com>
    Date:   Mon Sep 8 13:26:35 2014 -0300

        perf evlist: Refcount mmaps

        We need to know how many fds are using a perf mmap via
        PERF_EVENT_IOC_SET_OUTPUT, so that we can know when to ditch an mmap,
        refcount it.

This commit added 'int refcnt' to struct perf_mmap and the addition makes the
event_copy element no longer 8-byte aligned. Fix by adding a pad.

Signed-off-by: David Ahern <david.ahern@oracle.com>
---
 tools/perf/util/evlist.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index c94a9e03ecf1..7a5a77b2b907 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -28,6 +28,7 @@ struct perf_mmap {
 	int		 mask;
 	int		 refcnt;
 	unsigned int	 prev;
+	int		 pad;
 	char		 event_copy[PERF_SAMPLE_MAX_SIZE];
 };
 
-- 
1.9.3

Re: [PATCH] perf: Fix sigbus with perf-top

[Arnaldo Carvalho de Melo]

Em Wed, Feb 18, 2015 at 07:03:18PM -0500, David Ahern escreveu:
> perf-top is terminating due to SIGBUS on sparc64. git bisect points to:
> 
>     commit 82396986032915c1572bfb74b224fcc2e4e8ba7c
>     Author: Arnaldo Carvalho de Melo <acme@redhat.com>
>     Date:   Mon Sep 8 13:26:35 2014 -0300
> 
>         perf evlist: Refcount mmaps
> 
>         We need to know how many fds are using a perf mmap via
>         PERF_EVENT_IOC_SET_OUTPUT, so that we can know when to ditch an mmap,
>         refcount it.
> 
> This commit added 'int refcnt' to struct perf_mmap and the addition makes the
> event_copy element no longer 8-byte aligned. Fix by adding a pad.

I am applying this, but please consider doing like the kernel and using
one of those __aligned_on_foo struct member attributes.

I am adding a comment right after that pad...

- Arnaldo
 
> Signed-off-by: David Ahern <david.ahern@oracle.com>
> ---
>  tools/perf/util/evlist.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index c94a9e03ecf1..7a5a77b2b907 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -28,6 +28,7 @@ struct perf_mmap {
>  	int		 mask;
>  	int		 refcnt;
>  	unsigned int	 prev;
> +	int		 pad;
>  	char		 event_copy[PERF_SAMPLE_MAX_SIZE];
>  };
>  
> -- 
> 1.9.3

[tip:perf/urgent] perf top: Fix SIGBUS on sparc64

[tip-bot for David Ahern]

Commit-ID:  a73b6c199a663d64a38198f547d5c5be42163193
Gitweb:     http://git.kernel.org/tip/a73b6c199a663d64a38198f547d5c5be42163193
Author:     David Ahern <david.ahern@oracle.com>
AuthorDate: Wed, 18 Feb 2015 19:03:18 -0500
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 25 Feb 2015 17:37:44 -0300

perf top: Fix SIGBUS on sparc64

perf-top is terminating due to SIGBUS on sparc64. git bisect points to:

    commit 82396986032915c1572bfb74b224fcc2e4e8ba7c
    Author: Arnaldo Carvalho de Melo <acme@redhat.com>
    Date:   Mon Sep 8 13:26:35 2014 -0300

        perf evlist: Refcount mmaps

        We need to know how many fds are using a perf mmap via
        PERF_EVENT_IOC_SET_OUTPUT, so that we can know when to ditch an mmap,
        refcount it.

This commit added 'int refcnt' to struct perf_mmap and the addition makes the
event_copy element no longer 8-byte aligned.

Fix by adding __attribute__((aligned(8))) to the event_copy struct
member.

Signed-off-by: David Ahern <david.ahern@oracle.com>
Link: http://lkml.kernel.org/r/1424304198-92028-1-git-send-email-david.ahern@oracle.com
[ Switched from 'int pad;' to using __attribute__, David tested/acked that ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/evlist.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index c94a9e0..e99a676 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -28,7 +28,7 @@ struct perf_mmap {
 	int		 mask;
 	int		 refcnt;
 	unsigned int	 prev;
-	char		 event_copy[PERF_SAMPLE_MAX_SIZE];
+	char		 event_copy[PERF_SAMPLE_MAX_SIZE] __attribute__((aligned(8)));
 };
 
 struct perf_evlist {