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

Hengqi Chen
2026-02-26T07:00:18Z

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)
}
}

+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