On Wed, Apr 29, 2015 at 03:37:37PM +0200, Nicolas Schichan wrote:
> In that case, emit_udiv() will be called with rn == ARM_R0 (r_scratch)
> and loading rm first into ARM_R0 will result in jit_udiv() function
> being called the same dividend and divisor. Fix that by loading rn
> first into ARM_R1 and then rm into ARM_R0.
>
> Signed-off-by: Nicolas Schichan <nschic...@freebox.fr>
> ---
> arch/arm/net/bpf_jit_32.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
> index b5f470d..ffaf311 100644
> --- a/arch/arm/net/bpf_jit_32.c
> +++ b/arch/arm/net/bpf_jit_32.c
> @@ -449,10 +449,10 @@ static inline void emit_udiv(u8 rd, u8 rm, u8 rn,
> struct jit_ctx *ctx)
> return;
> }
> #endif
> - if (rm != ARM_R0)
> - emit(ARM_MOV_R(ARM_R0, rm), ctx);
> if (rn != ARM_R1)
> emit(ARM_MOV_R(ARM_R1, rn), ctx);
> + if (rm != ARM_R0)
> + emit(ARM_MOV_R(ARM_R0, rm), ctx);
I don't think you've thought enough about this. What if rm is ARM_R1?
What if rn = ARM_R0 and rm = ARM_R1?
How about:
if (rn == ARM_R0 && rm == ARM_R1) {
emit(ARM_MOV_R(ARM_R3, rn), ctx); // r3 <- r0(rn)
emit(ARM_MOV_R(ARM_R0, rm), ctx); // r0 <- r1(rm)
emit(ARM_MOV_R(ARM_R1, ARM_R3), ctx); // r1 <- r3
} else if (rn == ARM_R0) {
emit(ARM_MOV_R(ARM_R1, rn), ctx); // r1 <- rn
if (rm != ARM_R0)
emit(ARM_MOV_R(ARM_R0, rm), ctx); // r0 <- rm
} else {
if (rm != ARM_R0)
emit(ARM_MOV_R(ARM_R0, rm), ctx); // r0 <- rm
if (rn != ARM_R1)
emit(ARM_MOV_R(ARM_R1, rn), ctx); // r1 <- rn
}
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