Re: [PATCH 1/3] LoongArch: BPF: Introduce emit_store_stack_imm64() helper

Menglong Dong
2026-03-04T02:04:31Z

On 2026/2/26 14:59 Hengqi Chen <hengqi.chen@gmail.com> write:
> Introduce a helper to store 64-bit immediate on the trampoline stack.
> The helper will be used in the next patch. Also refactor the existing
> code to use this helper.
>
> Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
> ---
> arch/loongarch/net/bpf_jit.c | 24 +++++++++++++-----------
> 1 file changed, 13 insertions(+), 11 deletions(-)
>
> diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
> index 3bd89f55960d..e3deb0da6a50 100644
> --- a/arch/loongarch/net/bpf_jit.c
> +++ b/arch/loongarch/net/bpf_jit.c
> @@ -1480,6 +1480,12 @@ static void restore_args(struct jit_ctx *ctx, int nargs, int args_off)
> }
> }

LGTM.

Reviewed-by: Menglong Dong <menglong8.dong@gmail.com>

>
> +static void emit_store_stack_imm64(struct jit_ctx *ctx, int reg, int stack_off, u64 imm64)
> +{
> + move_imm(ctx, reg, imm64, false);
> + emit_insn(ctx, std, reg, LOONGARCH_GPR_FP, stack_off);
> +}
> +
> static int invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l,
> int args_off, int retval_off, int run_ctx_off, bool save_ret)
> {
> @@ -1488,12 +1494,11 @@ static int invoke_bpf_prog(struct jit_ctx *ctx, struct bpf_tramp_link *l,
> struct bpf_prog *p = l->link.prog;
> int cookie_off = offsetof(struct bpf_tramp_run_ctx, bpf_cookie);
>
> - if (l->cookie) {
> - move_imm(ctx, LOONGARCH_GPR_T1, l->cookie, false);
> - emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, -run_ctx_off + cookie_off);
> - } else {
> + if (l->cookie)
> + emit_store_stack_imm64(ctx, LOONGARCH_GPR_T1,
> + -run_ctx_off + cookie_off, l->cookie);
> + else
> emit_insn(ctx, std, LOONGARCH_GPR_ZERO, LOONGARCH_GPR_FP, -run_ctx_off + cookie_off);
> - }
>
> /* arg1: prog */
> move_imm(ctx, LOONGARCH_GPR_A0, (const s64)p, false);
> @@ -1726,14 +1731,11 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
> emit_insn(ctx, std, LOONGARCH_GPR_S1, LOONGARCH_GPR_FP, -sreg_off);
>
> /* store ip address of the traced function */
> - if (flags & BPF_TRAMP_F_IP_ARG) {
> - move_imm(ctx, LOONGARCH_GPR_T1, (const s64)func_addr, false);
> - emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, -ip_off);
> - }
> + if (flags & BPF_TRAMP_F_IP_ARG)
> + emit_store_stack_imm64(ctx, LOONGARCH_GPR_T1, -ip_off, (u64)func_addr);
>
> /* store nargs number */
> - move_imm(ctx, LOONGARCH_GPR_T1, nargs, false);
> - emit_insn(ctx, std, LOONGARCH_GPR_T1, LOONGARCH_GPR_FP, -nargs_off);
> + emit_store_stack_imm64(ctx, LOONGARCH_GPR_T1, -nargs_off, nargs);
>
> store_args(ctx, nargs, args_off);
>
> --
> 2.43.5
>
>
>