> On Jun 13, 2019, at 6:21 AM, Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
>
> Improve code readability by moving the BPF JIT function epilogue
> generation code to a dedicated emit_epilogue() function, analagous to
> the existing emit_prologue() function.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> ---
> arch/x86/net/bpf_jit_comp.c | 37 ++++++++++++++++++++++++-------------
> 1 file changed, 24 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
> index 32bfab4e21eb..da8c988b0f0f 100644
> --- a/arch/x86/net/bpf_jit_comp.c
> +++ b/arch/x86/net/bpf_jit_comp.c
> @@ -240,6 +240,28 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf)
> *pprog = prog;
> }
>
> +static void emit_epilogue(u8 **pprog)
> +{
> + u8 *prog = *pprog;
> + int cnt = 0;
> +
> + /* mov rbx, qword ptr [rbp+0] */
> + EMIT4(0x48, 0x8B, 0x5D, 0);
> + /* mov r13, qword ptr [rbp+8] */
> + EMIT4(0x4C, 0x8B, 0x6D, 8);
> + /* mov r14, qword ptr [rbp+16] */
> + EMIT4(0x4C, 0x8B, 0x75, 16);
> + /* mov r15, qword ptr [rbp+24] */
> + EMIT4(0x4C, 0x8B, 0x7D, 24);
Shall we update these comments to AT&T syntax?
Thanks,
Song
> +
> + /* add rbp, AUX_STACK_SPACE */
> + EMIT4(0x48, 0x83, 0xC5, AUX_STACK_SPACE);
> + EMIT1(0xC9); /* leave */
> + EMIT1(0xC3); /* ret */
> +
> + *pprog = prog;
> +}
> +
> /*
> * Generate the following code:
> *
> @@ -1036,19 +1058,8 @@ xadd: if (is_imm8(insn->off))
> seen_exit = true;
> /* Update cleanup_addr */
> ctx->cleanup_addr = proglen;
> - /* mov rbx, qword ptr [rbp+0] */
> - EMIT4(0x48, 0x8B, 0x5D, 0);
> - /* mov r13, qword ptr [rbp+8] */
> - EMIT4(0x4C, 0x8B, 0x6D, 8);
> - /* mov r14, qword ptr [rbp+16] */
> - EMIT4(0x4C, 0x8B, 0x75, 16);
> - /* mov r15, qword ptr [rbp+24] */
> - EMIT4(0x4C, 0x8B, 0x7D, 24);
> -
> - /* add rbp, AUX_STACK_SPACE */
> - EMIT4(0x48, 0x83, 0xC5, AUX_STACK_SPACE);
> - EMIT1(0xC9); /* leave */
> - EMIT1(0xC3); /* ret */
> +
> + emit_epilogue(&prog);
> break;
>
> default:
> --
> 2.20.1
>
