From: Nicolas Schichan <nschichan@freebox.fr>
To: Mircea Gherzan <mgherzan@gmail.com>,
Russell King <linux@arm.linux.org.uk>
Cc: Nicolas Schichan <nschichan@freebox.fr>,
"David S. Miller" <davem@davemloft.net>,
Daniel Borkmann <daniel.borkmann@tik.ee.ethz.ch>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.
Date: Wed, 13 Feb 2013 18:30:39 +0100 [thread overview]
Message-ID: <1360776645-14726-1-git-send-email-nschichan@freebox.fr> (raw)
In-Reply-To: <1360776125-14542-1-git-send-email-nschichan@freebox.fr>
The original code was generating an lsl instructions using the value
of ARM_R8 (skb_headlen, possibly uninitialized if no skb_headlen
access was required) as a shift amount.
Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
---
Resent due to missing Signed-off-by
arch/arm/net/bpf_jit_32.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index a34f1e2..6828ef6 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -341,10 +341,17 @@ static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx)
static inline void emit_swap16(u8 r_dst, u8 r_src, struct jit_ctx *ctx)
{
- emit(ARM_LSL_R(ARM_R1, r_src, 8), ctx);
- emit(ARM_ORR_S(r_dst, ARM_R1, r_src, SRTYPE_LSL, 8), ctx);
- emit(ARM_LSL_I(r_dst, r_dst, 8), ctx);
- emit(ARM_LSL_R(r_dst, r_dst, 8), ctx);
+ /* r_dst = (r_src << 8) | (r_src >> 8) */
+ emit(ARM_LSL_I(ARM_R1, r_src, 8), ctx);
+ emit(ARM_ORR_S(r_dst, ARM_R1, r_src, SRTYPE_LSR, 8), ctx);
+
+ /*
+ * we need to mask out the bits set in r_dst[23:16] due to
+ * the first shift instruction.
+ *
+ * note that 0x8ff is the encoded immediate 0x00ff0000.
+ */
+ emit(ARM_BIC_I(r_dst, r_dst, 0x8ff), ctx);
}
#else /* ARMv6+ */
--
1.7.10.4
next prev parent reply other threads:[~2013-02-13 17:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-13 17:22 [PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+ Nicolas Schichan
2013-02-13 17:30 ` Nicolas Schichan [this message]
2013-02-13 19:02 ` David Miller
2013-02-13 21:32 ` Mircea Gherzan
2013-02-14 13:40 ` Nicolas Schichan
2013-02-14 15:09 ` Russell King - ARM Linux
2013-02-14 18:27 ` David Miller
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