From: Jiri Olsa <jolsa@redhat.com>
Date: Mon, 6 Feb 2012 20:54:06 +0000 (-0200)
Subject: perf tools: Fix perf stack to non executable on x86_64
X-Git-Tag: firefly_0821_release~7541^2~1755
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f021e004b62bf213e3dfa70f747f1d3d6304fa6b;p=firefly-linux-kernel-4.4.55.git

perf tools: Fix perf stack to non executable on x86_64

commit 7a0153ee15575a4d07b5da8c96b79e0b0fd41a12 upstream.

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>
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/tools/perf/bench/mem-memcpy-x86-64-asm.S b/tools/perf/bench/mem-memcpy-x86-64-asm.S
index a57b66e853c2..185a96d66dd1 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