Enhance the bpf_arch_text_poke() function to enable accurate location of BPF program entry points.
When modifying the entry point of a BPF program, skip the move t0, ra instruction to ensure the correct logic and copy of the jump address. Signed-off-by: Chenghao Duan <[email protected]> --- arch/loongarch/net/bpf_jit.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c index 3dbabacc8856..0c16a1b18e8f 100644 --- a/arch/loongarch/net/bpf_jit.c +++ b/arch/loongarch/net/bpf_jit.c @@ -1290,6 +1290,10 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t, void *new_addr) { int ret; + unsigned long size = 0; + unsigned long offset = 0; + char namebuf[KSYM_NAME_LEN]; + void *image = NULL; bool is_call; u32 old_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP}; u32 new_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP}; @@ -1297,9 +1301,18 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t, /* Only poking bpf text is supported. Since kernel function entry * is set up by ftrace, we rely on ftrace to poke kernel functions. */ - if (!is_bpf_text_address((unsigned long)ip)) + if (!__bpf_address_lookup((unsigned long)ip, &size, &offset, namebuf)) return -ENOTSUPP; + image = ip - offset; + /* zero offset means we're poking bpf prog entry */ + if (offset == 0) + /* skip to the nop instruction in bpf prog entry: + * move t0, ra + * nop + */ + ip = image + LOONGARCH_INSN_SIZE; + is_call = old_t == BPF_MOD_CALL; ret = emit_jump_or_nops(old_addr, ip, old_insns, is_call); if (ret) -- 2.25.1
