[PATCH bpf-next v2 05/21] bpf, x86: Introduce bpf_arch_text_poke_batch() on x86_64

[Leon Hwang <leon.hwang@linux.dev>]

Introduce bpf_arch_text_poke_batch() to patch multiple targets in batch,
which utilizes smp_text_poke_batch_add/finish() on x86_64.

Thereafter, it will able to text-poke multiple bpf progs at once via
bpf_arch_text_poke_batch().

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
 arch/x86/net/bpf_jit_comp.c | 41 +++++++++++++++++++++++++++++++++++++
 include/linux/bpf.h         |  9 ++++++++
 kernel/bpf/core.c           |  5 +++++
 3 files changed, 55 insertions(+)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index c80d3161d458..b2040ae09273 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -734,6 +734,47 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t,
 	return __bpf_arch_text_poke(ip, old_t, new_t, old_addr, new_addr);
 }
 
+int bpf_arch_text_poke_batch(struct bpf_text_poke **pokes, u32 cnt)
+{
+	u8 old_insn[X86_PATCH_SIZE];
+	u8 new_insn[X86_PATCH_SIZE];
+	int err;
+	u32 i;
+
+	for (i = 0; i < cnt; i++) {
+		err = bpf_arch_text_poke_check_ip(&pokes[i]->ip);
+		if (err)
+			return err;
+	}
+
+	guard(mutex)(&text_mutex);
+
+	for (i = 0; i < cnt; i++) {
+		struct bpf_text_poke *poke = pokes[i];
+
+		err = bpf_arch_text_poke_prepare_insns(poke->ip, poke->old_t, poke->new_t,
+						       poke->old_addr, poke->new_addr, old_insn,
+						       new_insn);
+		if (err)
+			return err;
+		if (memcmp(poke->ip, old_insn, X86_PATCH_SIZE))
+			return -EBUSY;
+	}
+
+	for (i = 0; i < cnt; i++) {
+		struct bpf_text_poke *poke = pokes[i];
+
+		bpf_arch_text_poke_prepare_insns(poke->ip, poke->old_t, poke->new_t,
+						 poke->old_addr, poke->new_addr, old_insn,
+						 new_insn);
+		if (memcmp(poke->ip, new_insn, X86_PATCH_SIZE))
+			smp_text_poke_batch_add(poke->ip, new_insn, X86_PATCH_SIZE, NULL);
+	}
+
+	smp_text_poke_batch_finish();
+	return 0;
+}
+
 #define EMIT_LFENCE()	EMIT3(0x0F, 0xAE, 0xE8)
 
 static void __emit_indirect_jump(u8 **pprog, int reg, bool ereg)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 54144372281c..5b1a189e6e89 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -4231,6 +4231,15 @@ enum bpf_text_poke_type {
 	BPF_MOD_JUMP,
 };
 
+struct bpf_text_poke {
+	void *ip;
+	void *old_addr;
+	void *new_addr;
+	enum bpf_text_poke_type old_t;
+	enum bpf_text_poke_type new_t;
+};
+
+int bpf_arch_text_poke_batch(struct bpf_text_poke **pokes, u32 cnt);
 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t,
 		       enum bpf_text_poke_type new_t, void *old_addr,
 		       void *new_addr);
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 05c89396119a..49b794878c11 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -3484,6 +3484,11 @@ int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to,
 	return -EFAULT;
 }
 
+int __weak bpf_arch_text_poke_batch(struct bpf_text_poke **pokes, u32 cnt)
+{
+	return -EOPNOTSUPP;
+}
+
 int __weak bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t,
 			      enum bpf_text_poke_type new_t, void *old_addr,
 			      void *new_addr)
-- 
2.55.0