[PATCH v4 4/7] LoongArch: BPF: Save return address register ra to t0 before trampoline
From: Chenghao Duan <hidden>
Date: 2025-12-17 06:14:56
Also in:
bpf, lkml, loongarch
Subsystem:
bpf jit for loongarch, bpf [general] (safe dynamic programs and tools), loongarch, the rest · Maintainers:
Tiezhu Yang, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Huacai Chen, Linus Torvalds
Modify the build_prologue function to ensure the return address register ra is saved to t0 before entering trampoline operations. This change ensures accurate return address handling when a BPF program calls another BPF program, preventing errors in the BPF-to-BPF call chain. Signed-off-by: Chenghao Duan <redacted> --- arch/loongarch/net/bpf_jit.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
index 76cd24646bec..c560d1e14b9d 100644
--- a/arch/loongarch/net/bpf_jit.c
+++ b/arch/loongarch/net/bpf_jit.c@@ -139,6 +139,7 @@ static void build_prologue(struct jit_ctx *ctx) stack_adjust = round_up(stack_adjust, 16); stack_adjust += bpf_stack_adjust; + move_reg(ctx, LOONGARCH_GPR_T0, LOONGARCH_GPR_RA); /* Reserve space for the move_imm + jirl instruction */ for (i = 0; i < LOONGARCH_LONG_JUMP_NINSNS; i++) emit_insn(ctx, nop);
--
2.25.1