[PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.

[PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.

[Nicolas Schichan]

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.
---
 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

[PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.

[Nicolas Schichan]

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

Re: [PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.

[David Miller]

From: Nicolas Schichan <nschichan@freebox.fr>
Date: Wed, 13 Feb 2013 18:30:39 +0100

> 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>

ARM folks do you want to pick this up or would you like me to
apply it to the 'net' tree?

Re: [PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.

[Mircea Gherzan]

Am 13.02.2013 18:30, schrieb Nicolas Schichan:
> 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+ */

Acked-by: Mircea Gherzan <mgherzan@gmail.com>

Re: [PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.

[Nicolas Schichan]

On 02/13/2013 10:32 PM, Mircea Gherzan wrote:
[...]
> Acked-by: Mircea Gherzan <mgherzan@gmail.com>

Hi,

Thanks Mircea. Russel, David, do you have any preference as to which path this 
patch should take (net tree or ARM tree) ?

Regards,

-- 
Nicolas Schichan
Freebox SAS

Re: [PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.

[Russell King - ARM Linux]

On Thu, Feb 14, 2013 at 02:40:09PM +0100, Nicolas Schichan wrote:
> On 02/13/2013 10:32 PM, Mircea Gherzan wrote:
> [...]
>> Acked-by: Mircea Gherzan <mgherzan@gmail.com>
>
> Hi,
>
> Thanks Mircea. Russel, David, do you have any preference as to which path 
> this patch should take (net tree or ARM tree) ?

I'm happy for either - I'm under the weather at the moment, so I'd be
greatful if David could pick this one up this time around.

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

Thanks.

Re: [PATCH] ARM: net: bpf_jit: fix emit_swap16() for non ARMv6+.

[David Miller]

From: Russell King - ARM Linux <linux@arm.linux.org.uk>
Date: Thu, 14 Feb 2013 15:09:25 +0000

> On Thu, Feb 14, 2013 at 02:40:09PM +0100, Nicolas Schichan wrote:
>> On 02/13/2013 10:32 PM, Mircea Gherzan wrote:
>> [...]
>>> Acked-by: Mircea Gherzan <mgherzan@gmail.com>
>>
>> Hi,
>>
>> Thanks Mircea. Russel, David, do you have any preference as to which path 
>> this patch should take (net tree or ARM tree) ?
> 
> I'm happy for either - I'm under the weather at the moment, so I'd be
> greatful if David could pick this one up this time around.
> 
> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

Applied to 'net', thanks everyone.