linux-kernel - [PATCH v7 bpf-next 6/9] bpf: introduce bpf_arch_text

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Message-ID: <20220128234517.3503701-7-song@kernel.org>
Date:   Fri, 28 Jan 2022 15:45:14 -0800
From:   Song Liu <song@...nel.org>
To:     <bpf@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <ast@...nel.org>, <daniel@...earbox.net>, <andrii@...nel.org>,
        <kernel-team@...com>, <peterz@...radead.org>, <x86@...nel.org>,
        <iii@...ux.ibm.com>, Song Liu <song@...nel.org>
Subject: [PATCH v7 bpf-next 6/9] bpf: introduce bpf_arch_text_copy

This will be used to copy JITed text to RO protected module memory. On
x86, bpf_arch_text_copy is implemented with text_poke_copy.

bpf_arch_text_copy returns pointer to dst on success, and ERR_PTR(errno)
on errors.

Signed-off-by: Song Liu <song@...nel.org>
---
 arch/x86/net/bpf_jit_comp.c | 7 +++++++
 include/linux/bpf.h         | 2 ++
 kernel/bpf/core.c           | 5 +++++
 3 files changed, 14 insertions(+)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index ce1f86f245c9..9792bf10d881 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -2413,3 +2413,10 @@ bool bpf_jit_supports_kfunc_call(void)
 {
 	return true;
 }
+
+void *bpf_arch_text_copy(void *dst, void *src, size_t len)
+{
+	if (text_poke_copy(dst, src, len) == NULL)
+		return ERR_PTR(-EINVAL);
+	return dst;
+}
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 28ac752f21ba..7f58fe256671 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2350,6 +2350,8 @@ enum bpf_text_poke_type {
 int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 		       void *addr1, void *addr2);
 
+void *bpf_arch_text_copy(void *dst, void *src, size_t len);
+
 struct btf_id_set;
 bool btf_id_set_contains(const struct btf_id_set *set, u32 id);
 
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 7cbcf6bfbb52..dc0142e20c72 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2448,6 +2448,11 @@ int __weak bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 	return -ENOTSUPP;
 }
 
+void * __weak bpf_arch_text_copy(void *dst, void *src, size_t len)
+{
+	return ERR_PTR(-ENOTSUPP);
+}
+
 DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
 EXPORT_SYMBOL(bpf_stats_enabled_key);
 
-- 
2.30.2