[3.11.y.z extended stable] Patch "x86: bpf_jit: support negative offsets" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    x86: bpf_jit: support negative offsets

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 0daa3f20772cd2237f670819dbdf9bd59ea071ba Mon Sep 17 00:00:00 2001
From: Alexei Starovoitov <ast at plumgrid.com>
Date: Mon, 10 Mar 2014 15:56:51 -0700
Subject: x86: bpf_jit: support negative offsets

commit fdfaf64e75397567257e1051931f9a3377360665 upstream.

Commit a998d4342337 claimed to introduce negative offset support to x86 jit,
but it couldn't be working, since at the time of the execution
of LD+ABS or LD+IND instructions via call into
bpf_internal_load_pointer_neg_helper() the %edx (3rd argument of this func)
had junk value instead of access size in bytes (1 or 2 or 4).

Store size into %edx instead of %ecx (what original commit intended to do)

Fixes: a998d4342337 ("bpf jit: Let the x86 jit handle negative offsets")
Signed-off-by: Alexei Starovoitov <ast at plumgrid.com>
Cc: Jan Seiffert <kaffeemonster at googlemail.com>
Cc: Eric Dumazet <edumazet at google.com>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/x86/net/bpf_jit.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit.S b/arch/x86/net/bpf_jit.S
index 877b9a1..0149575 100644
--- a/arch/x86/net/bpf_jit.S
+++ b/arch/x86/net/bpf_jit.S
@@ -140,7 +140,7 @@ bpf_slow_path_byte_msh:
 	push	%r9;						\
 	push	SKBDATA;					\
 /* rsi already has offset */					\
-	mov	$SIZE,%ecx;	/* size */			\
+	mov	$SIZE,%edx;	/* size */			\
 	call	bpf_internal_load_pointer_neg_helper;		\
 	test	%rax,%rax;					\
 	pop	SKBDATA;					\
--
1.9.1