2021-05-10 13:14:16

by Tiezhu Yang

Subject: [PATCH bpf-next] bpf: arm64: Replace STACK_ALIGN() with round_up() to align stack size

Use the common function round_up() directly to show the align size
explicitly, the function STACK_ALIGN() is needless, remove it.

Signed-off-by: Tiezhu Yang <[email protected]>
---
arch/arm64/net/bpf_jit_comp.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index f7b1948..81c380f 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -178,9 +178,6 @@ static bool is_addsub_imm(u32 imm)
return !(imm & ~0xfff) || !(imm & ~0xfff000);
}

-/* Stack must be multiples of 16B */
-#define STACK_ALIGN(sz) (((sz) + 15) & ~15)
-
/* Tail call offset to jump into */
#if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)
#define PROLOGUE_OFFSET 8
@@ -255,7 +252,7 @@ static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf)
emit(A64_BTI_J, ctx);
}

- ctx->stack_size = STACK_ALIGN(prog->aux->stack_depth);
+ ctx->stack_size = round_up(prog->aux->stack_depth, 16);

/* Set up function call stack */
emit(A64_SUB_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
--
2.1.0

2021-05-12 22:09:27

by Daniel Borkmann

Subject: Re: [PATCH bpf-next] bpf: arm64: Replace STACK_ALIGN() with round_up() to align stack size

On 5/10/21 2:51 PM, Tiezhu Yang wrote:
> Use the common function round_up() directly to show the align size
> explicitly, the function STACK_ALIGN() is needless, remove it.
>
> Signed-off-by: Tiezhu Yang <[email protected]>
> ---
> arch/arm64/net/bpf_jit_comp.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
> index f7b1948..81c380f 100644
> --- a/arch/arm64/net/bpf_jit_comp.c
> +++ b/arch/arm64/net/bpf_jit_comp.c
> @@ -178,9 +178,6 @@ static bool is_addsub_imm(u32 imm)
> return !(imm & ~0xfff) || !(imm & ~0xfff000);
> }
>
> -/* Stack must be multiples of 16B */
> -#define STACK_ALIGN(sz) (((sz) + 15) & ~15)
> -
> /* Tail call offset to jump into */
> #if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL)
> #define PROLOGUE_OFFSET 8
> @@ -255,7 +252,7 @@ static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf)
> emit(A64_BTI_J, ctx);
> }
>
> - ctx->stack_size = STACK_ALIGN(prog->aux->stack_depth);
> + ctx->stack_size = round_up(prog->aux->stack_depth, 16);
>

Applied, thanks! (I retained the comment wrt stack requirement to have it explicitly stated.)