[PATCH] perf, tool: Fix perf stack to non executable on x86_64

[PATCH] perf, tool: Fix perf stack to non executable on x86_64

[Jiri Olsa]

By adding following objects:
  bench/mem-memset-x86-64-asm.o
  bench/mem-memcpy-x86-64-asm.o
the x86_64 perf binary ended up with executable stack.

The reason was that above objects are assembler sourced and
are missing the GNU-stack note section. In such case the linker
assumes that the final binary should not be restricted at all
and mark the stack as RWX.

Adding section ".note.GNU-stack" definition to mentioned objects,
with all flags disabled, thus omiting those objects from linker
stack flags decision.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
---
 tools/perf/bench/mem-memcpy-x86-64-asm.S |    7 +++++++
 tools/perf/bench/mem-memset-x86-64-asm.S |    7 +++++++
 2 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/tools/perf/bench/mem-memcpy-x86-64-asm.S b/tools/perf/bench/mem-memcpy-x86-64-asm.S
index a20780b..a6c8909 100644
--- a/tools/perf/bench/mem-memcpy-x86-64-asm.S
+++ b/tools/perf/bench/mem-memcpy-x86-64-asm.S
@@ -4,3 +4,10 @@
 #define Lmemcpy_c globl memcpy_c; memcpy_c
 #define Lmemcpy_c_e globl memcpy_c_e; memcpy_c_e
 #include "../../../arch/x86/lib/memcpy_64.S"
+
+/*
+ * We need to provide note.GNU-stack section, saying that we want
+ * NOT executable stack. Otherwise the final linking will assume that
+ * the ELF stack should not be restricted at all and set it RWX.
+ */
+.section .note.GNU-stack,"",@progbits
diff --git a/tools/perf/bench/mem-memset-x86-64-asm.S b/tools/perf/bench/mem-memset-x86-64-asm.S
index cb92170..9e5af89 100644
--- a/tools/perf/bench/mem-memset-x86-64-asm.S
+++ b/tools/perf/bench/mem-memset-x86-64-asm.S
@@ -4,3 +4,10 @@
 #define Lmemset_c globl memset_c; memset_c
 #define Lmemset_c_e globl memset_c_e; memset_c_e
 #include "../../../arch/x86/lib/memset_64.S"
+
+/*
+ * We need to provide note.GNU-stack section, saying that we want
+ * NOT executable stack. Otherwise the final linking will assume that
+ * the ELF stack should not be restricted at all and set it RWX.
+ */
+.section .note.GNU-stack,"",@progbits
-- 
1.7.1

Re: [PATCH] perf, tool: Fix perf stack to non executable on x86_64

[Eric Dumazet]

Le mercredi 01 février 2012 à 13:54 +0100, Jiri Olsa a écrit :
> By adding following objects:
>   bench/mem-memset-x86-64-asm.o
>   bench/mem-memcpy-x86-64-asm.o
> the x86_64 perf binary ended up with executable stack.
> 
> The reason was that above objects are assembler sourced and
> are missing the GNU-stack note section. In such case the linker
> assumes that the final binary should not be restricted at all
> and mark the stack as RWX.
> 
> Adding section ".note.GNU-stack" definition to mentioned objects,
> with all flags disabled, thus omiting those objects from linker
> stack flags decision.
> 
> Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> ---

Good catch, thanks !

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

[tip:perf/core] perf tools: Fix perf stack to non executable on x86_64

[tip-bot for Jiri Olsa]

Commit-ID:  7a0153ee15575a4d07b5da8c96b79e0b0fd41a12
Gitweb:     http://git.kernel.org/tip/7a0153ee15575a4d07b5da8c96b79e0b0fd41a12
Author:     Jiri Olsa <jolsa@redhat.com>
AuthorDate: Mon, 6 Feb 2012 18:54:06 -0200
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 6 Feb 2012 18:54:06 -0200

perf tools: Fix perf stack to non executable on x86_64

By adding following objects:
  bench/mem-memcpy-x86-64-asm.o
the x86_64 perf binary ended up with executable stack.

The reason was that above object are assembler sourced and is missing the
GNU-stack note section. In such case the linker assumes that the final binary
should not be restricted at all and mark the stack as RWX.

Adding section ".note.GNU-stack" definition to mentioned object, with all
flags disabled, thus omiting this object from linker stack flags decision.

Problem introduced in:

  $ git describe ea7872b
  v2.6.37-rc2-19-gea7872b

Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=783570
Reported-by: Clark Williams <williams@redhat.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1328100848-5630-1-git-send-email-jolsa@redhat.com
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
[ committer note: Backported fix to perf/urgent (3.3-rc2+) ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/bench/mem-memcpy-x86-64-asm.S |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/tools/perf/bench/mem-memcpy-x86-64-asm.S b/tools/perf/bench/mem-memcpy-x86-64-asm.S
index a57b66e..185a96d 100644
--- a/tools/perf/bench/mem-memcpy-x86-64-asm.S
+++ b/tools/perf/bench/mem-memcpy-x86-64-asm.S
@@ -1,2 +1,8 @@
 
 #include "../../../arch/x86/lib/memcpy_64.S"
+/*
+ * We need to provide note.GNU-stack section, saying that we want
+ * NOT executable stack. Otherwise the final linking will assume that
+ * the ELF stack should not be restricted at all and set it RWX.
+ */
+.section .note.GNU-stack,"",@progbits

[tip:perf/core] perf tool: Fix perf stack to non executable on x86_64

[tip-bot for Jiri Olsa]

Commit-ID:  e89cef136a8b56eef1acf702591fd3039fc3385d
Gitweb:     http://git.kernel.org/tip/e89cef136a8b56eef1acf702591fd3039fc3385d
Author:     Jiri Olsa <jolsa@redhat.com>
AuthorDate: Wed, 1 Feb 2012 13:54:08 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 6 Feb 2012 19:14:17 -0200

perf tool: Fix perf stack to non executable on x86_64

By adding following objects:
  bench/mem-memset-x86-64-asm.o
  bench/mem-memcpy-x86-64-asm.o
the x86_64 perf binary ended up with executable stack.

The reason was that above objects are assembler sourced and are missing the
GNU-stack note section. In such case the linker assumes that the final binary
should not be restricted at all and mark the stack as RWX.

Adding section ".note.GNU-stack" definition to mentioned objects, with all
flags disabled, thus omiting those objects from linker stack flags decision.

Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=783570
Reported-by: Clark Williams <williams@redhat.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1328100848-5630-1-git-send-email-jolsa@redhat.com
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
[ committer note: Remaining bits after what was already added to perf/urgent ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/bench/mem-memset-x86-64-asm.S |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/tools/perf/bench/mem-memset-x86-64-asm.S b/tools/perf/bench/mem-memset-x86-64-asm.S
index cb92170..9e5af89 100644
--- a/tools/perf/bench/mem-memset-x86-64-asm.S
+++ b/tools/perf/bench/mem-memset-x86-64-asm.S
@@ -4,3 +4,10 @@
 #define Lmemset_c globl memset_c; memset_c
 #define Lmemset_c_e globl memset_c_e; memset_c_e
 #include "../../../arch/x86/lib/memset_64.S"
+
+/*
+ * We need to provide note.GNU-stack section, saying that we want
+ * NOT executable stack. Otherwise the final linking will assume that
+ * the ELF stack should not be restricted at all and set it RWX.
+ */
+.section .note.GNU-stack,"",@progbits