On Thu, Nov 07, 2013 at 12:09:59PM +0100, Eric Bénard wrote:
> From: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>
>
> Commit 455bd4c430b0 ("ARM: 7668/1: fix memset-related crashes caused by
> recent GCC (4.7.2) optimizations") attempted to fix a compliance issue
> with the memset return value. However the memset itself became broken
> by that patch for misaligned pointers.
>
> This fixes the above by branching over the entry code from the
> misaligned fixup code to avoid reloading the original pointer.
>
> Also, because the function entry alignment is wrong in the Thumb mode
> compilation, that fixup code is moved to the end.
>
> While at it, the entry instructions are slightly reworked to help dual
> issue pipelines.
>
> * For stable 3.4.x :
> this patch allows the kernel to boot when compiled with recent GCC
> (tested with gcc 4.8.1 on and ARMv7 target)
>
> This patch is in master :
> 418df63a ARM: 7670/1: fix the memset fix
> and depends on :
> 455bd4c ARM: 7668/1: fix memset-related crashes caused by recent GCC (4.7.2) optimizations
Thanks Eric, I'm queuing both of these commits for the 3.5 kernel.
Cheers,
--
Luis
>
> Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxx> Tested-by: Alexander
> Holler <holler@xxxxxxxxxxxxx> Signed-off-by: Russell King
> <rmk+kernel@xxxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # 3.4.x:
> 455bd4c ARM: 7668/1: fix memset-related crashes caused by recent GCC
> (4.7.2) optimizations Cc: <stable@xxxxxxxxxxxxxxx> # 3.4.x ---
> arch/arm/lib/memset.S | 33 +++++++++++++-------------------- 1 file
> changed, 13 insertions(+), 20 deletions(-)
>
> diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S
> index d912e73..94b0650 100644
> --- a/arch/arm/lib/memset.S
> +++ b/arch/arm/lib/memset.S
> @@ -14,31 +14,15 @@
>
> .text
> .align 5
> - .word 0
> -
> -1: subs r2, r2, #4 @ 1 do we have enough
> - blt 5f @ 1 bytes to align with?
> - cmp r3, #2 @ 1
> - strltb r1, [ip], #1 @ 1
> - strleb r1, [ip], #1 @ 1
> - strb r1, [ip], #1 @ 1
> - add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
> -/*
> - * The pointer is now aligned and the length is adjusted. Try doing the
> - * memset again.
> - */
>
> ENTRY(memset)
> -/*
> - * Preserve the contents of r0 for the return value.
> - */
> - mov ip, r0
> - ands r3, ip, #3 @ 1 unaligned?
> - bne 1b @ 1
> + ands r3, r0, #3 @ 1 unaligned?
> + mov ip, r0 @ preserve r0 as return value
> + bne 6f @ 1
> /*
> * we know that the pointer in ip is aligned to a word boundary.
> */
> - orr r1, r1, r1, lsl #8
> +1: orr r1, r1, r1, lsl #8
> orr r1, r1, r1, lsl #16
> mov r3, r1
> cmp r2, #16
> @@ -127,4 +111,13 @@ ENTRY(memset)
> tst r2, #1
> strneb r1, [ip], #1
> mov pc, lr
> +
> +6: subs r2, r2, #4 @ 1 do we have enough
> + blt 5b @ 1 bytes to align with?
> + cmp r3, #2 @ 1
> + strltb r1, [ip], #1 @ 1
> + strleb r1, [ip], #1 @ 1
> + strb r1, [ip], #1 @ 1
> + add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
> + b 1b
> ENDPROC(memset)
> --
> 1.8.3.1
>
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