Commit 73721d86 authored by Chenghao Duan's avatar Chenghao Duan Committed by Huacai Chen
Browse files

LoongArch: BPF: Enhance the bpf_arch_text_poke() function 



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.

Cc: stable@vger.kernel.org
Fixes: 677e6123 ("LoongArch: BPF: Disable trampoline for kernel module function trace")
Signed-off-by: default avatarChenghao Duan <duanchenghao@kylinos.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 26138762

arch/loongarch/net/bpf_jit.c

+16 −1
Original line number Diff line number Diff line
@@ -1309,15 +1309,30 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t, 
{

	int ret;

	bool is_call;

	unsigned long size = 0;

	unsigned long offset = 0;

	void *image = NULL;

	char namebuf[KSYM_NAME_LEN];

	u32 old_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP};

	u32 new_insns[LOONGARCH_LONG_JUMP_NINSNS] = {[0 ... 4] = INSN_NOP};



	/* 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)