netdev - [PATCH net-next v2 2/5] s390/bpf: Fix multiple macro expansions

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Date:	Wed, 29 Jul 2015 10:45:40 +0200
From:	Michael Holzheu <holzheu@...ux.vnet.ibm.com>
To:	David Miller <davem@...emloft.net>
Cc:	Alexei Starovoitov <ast@...mgrid.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	Joe Perches <joe@...ches.com>, netdev@...r.kernel.org,
	linux-s390@...r.kernel.org
Subject: [PATCH net-next v2 2/5] s390/bpf: Fix multiple macro expansions

The EMIT6_DISP_LH macro passes the "disp" parameter to the _EMIT6_DISP_LH
macro. The _EMIT6_DISP_LH macro uses the "disp" parameter twice:

 unsigned int __disp_h = ((u32)disp) & 0xff000;
 unsigned int __disp_l = ((u32)disp) & 0x00fff;

The EMIT6_DISP_LH is used several times with EMIT_CONST_U64() as "disp"
parameter. Therefore always two constants are created per usage of
EMIT6_DISP_LH.

Fix this and add variable "_disp" to avoid multiple expansions.

* v2: Move "_disp" to _EMIT6_DISP_LH as suggested by Joe Perches

Fixes: 054623105728 ("s390/bpf: Add s390x eBPF JIT compiler backend")
Signed-off-by: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
---
 arch/s390/net/bpf_jit_comp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 01ad166..66926ab 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -214,8 +214,9 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
 
 #define _EMIT6_DISP_LH(op1, op2, disp)				\
 ({								\
-	unsigned int __disp_h = ((u32)disp) & 0xff000;		\
-	unsigned int __disp_l = ((u32)disp) & 0x00fff;		\
+	u32 _disp = (u32) disp;					\
+	unsigned int __disp_h = _disp & 0xff000;		\
+	unsigned int __disp_l = _disp & 0x00fff;		\
 	_EMIT6(op1 | __disp_l, op2 | __disp_h >> 4);		\
 })
 
-- 
2.3.8

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