From ea645cfd3d5f74a2bd40a60003f113b3c467975d Mon Sep 17 00:00:00 2001 From: Hengqi Chen Date: Thu, 2 Oct 2025 22:39:52 +0800 Subject: [PATCH] LoongArch: BPF: Make trampoline size stable When attach fentry/fexit BPF programs, __arch_prepare_bpf_trampoline() is called twice with different `struct bpf_tramp_image *im`: bpf_trampoline_update() -> arch_bpf_trampoline_size() -> __arch_prepare_bpf_trampoline() -> arch_prepare_bpf_trampoline() -> __arch_prepare_bpf_trampoline() Use move_imm() will emit unstable instruction sequences, so let's use move_addr() instead to prevent subtle bugs. (I observed this while debugging other issues with printk.) Cc: stable@vger.kernel.org Tested-by: Vincent Li Signed-off-by: Hengqi Chen Signed-off-by: Huacai Chen --- arch/loongarch/net/bpf_jit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 8d5547014b2c..a941a9f4c337 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -1595,7 +1595,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i orig_call += LOONGARCH_BPF_FENTRY_NBYTES; if (flags & BPF_TRAMP_F_CALL_ORIG) { - move_imm(ctx, LOONGARCH_GPR_A0, (const s64)im, false); + move_addr(ctx, LOONGARCH_GPR_A0, (const u64)im); ret = emit_call(ctx, (const u64)__bpf_tramp_enter); if (ret) return ret; @@ -1645,7 +1645,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i if (flags & BPF_TRAMP_F_CALL_ORIG) { im->ip_epilogue = ctx->ro_image + ctx->idx; - move_imm(ctx, LOONGARCH_GPR_A0, (const s64)im, false); + move_addr(ctx, LOONGARCH_GPR_A0, (const u64)im); ret = emit_call(ctx, (const u64)__bpf_tramp_exit); if (ret) goto out; -- 2.47.3