From: Song Liu <song@kernel.org>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: <ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>,
<kernel-team@fb.com>, <peterz@infradead.org>, <x86@kernel.org>,
<iii@linux.ibm.com>, Song Liu <song@kernel.org>
Subject: [PATCH v9 bpf-next 5/9] x86/alternative: introduce text_poke_copy
Date: Fri, 4 Feb 2022 10:57:38 -0800 [thread overview]
Message-ID: <20220204185742.271030-6-song@kernel.org> (raw)
In-Reply-To: <20220204185742.271030-1-song@kernel.org>
This will be used by BPF jit compiler to dump JITed binary to a RX huge
page, and thus allow multiple BPF programs sharing the a huge (2MB) page.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Song Liu <song@kernel.org>
---
arch/x86/include/asm/text-patching.h | 1 +
arch/x86/kernel/alternative.c | 34 ++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index b7421780e4e9..4cc18ba1b75e 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -44,6 +44,7 @@ extern void text_poke_early(void *addr, const void *opcode, size_t len);
extern void *text_poke(void *addr, const void *opcode, size_t len);
extern void text_poke_sync(void);
extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len);
+extern void *text_poke_copy(void *addr, const void *opcode, size_t len);
extern int poke_int3_handler(struct pt_regs *regs);
extern void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate);
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 5007c3ffe96f..018b61febf0e 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1102,6 +1102,40 @@ void *text_poke_kgdb(void *addr, const void *opcode, size_t len)
return __text_poke(addr, opcode, len);
}
+/**
+ * text_poke_copy - Copy instructions into (an unused part of) RX memory
+ * @addr: address to modify
+ * @opcode: source of the copy
+ * @len: length to copy, could be more than 2x PAGE_SIZE
+ *
+ * Not safe against concurrent execution; useful for JITs to dump
+ * new code blocks into unused regions of RX memory. Can be used in
+ * conjunction with synchronize_rcu_tasks() to wait for existing
+ * execution to quiesce after having made sure no existing functions
+ * pointers are live.
+ */
+void *text_poke_copy(void *addr, const void *opcode, size_t len)
+{
+ unsigned long start = (unsigned long)addr;
+ size_t patched = 0;
+
+ if (WARN_ON_ONCE(core_kernel_text(start)))
+ return NULL;
+
+ mutex_lock(&text_mutex);
+ while (patched < len) {
+ unsigned long ptr = start + patched;
+ size_t s;
+
+ s = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(ptr), len - patched);
+
+ __text_poke((void *)ptr, opcode + patched, s);
+ patched += s;
+ }
+ mutex_unlock(&text_mutex);
+ return addr;
+}
+
static void do_sync_core(void *info)
{
sync_core();
--
2.30.2
next prev parent reply other threads:[~2022-02-04 19:01 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 18:57 [PATCH v9 bpf-next 0/9] bpf_prog_pack allocator Song Liu
2022-02-04 18:57 ` [PATCH v9 bpf-next 1/9] x86/Kconfig: select HAVE_ARCH_HUGE_VMALLOC with HAVE_ARCH_HUGE_VMAP Song Liu
2022-03-26 0:06 ` Edgecombe, Rick P
2022-03-28 23:27 ` Song Liu
2022-03-29 0:18 ` Edgecombe, Rick P
2022-03-29 8:23 ` Song Liu
2022-03-29 18:39 ` Edgecombe, Rick P
2022-03-29 19:13 ` Song Liu
2022-03-29 21:36 ` Edgecombe, Rick P
2022-03-29 22:12 ` Song Liu
2022-03-26 18:46 ` BUG: Bad page state in process systemd-udevd (was: [PATCH v9 bpf-next 1/9] x86/Kconfig: select HAVE_ARCH_HUGE_VMALLOC with HAVE_ARCH_HUGE_VMAP) Paul Menzel
2022-03-27 10:36 ` Paul Menzel
2022-03-28 6:37 ` Song Liu
2022-03-28 6:51 ` Paul Menzel
2022-03-28 19:24 ` Song Liu
2022-03-28 20:14 ` Paul Menzel
2022-03-28 21:57 ` Song Liu
2022-03-28 19:21 ` Edgecombe, Rick P
2022-02-04 18:57 ` [PATCH v9 bpf-next 2/9] bpf: use bytes instead of pages for bpf_jit_[charge|uncharge]_modmem Song Liu
2022-02-04 18:57 ` [PATCH v9 bpf-next 3/9] bpf: use size instead of pages in bpf_binary_header Song Liu
2022-02-04 18:57 ` [PATCH v9 bpf-next 4/9] bpf: use prog->jited_len in bpf_prog_ksym_set_addr() Song Liu
2022-02-04 18:57 ` Song Liu [this message]
2022-02-04 18:57 ` [PATCH v9 bpf-next 6/9] bpf: introduce bpf_arch_text_copy Song Liu
2022-02-04 18:57 ` [PATCH v9 bpf-next 7/9] bpf: introduce bpf_prog_pack allocator Song Liu
2022-02-04 18:57 ` [PATCH v9 bpf-next 8/9] bpf: introduce bpf_jit_binary_pack_[alloc|finalize|free] Song Liu
2022-02-04 18:57 ` [PATCH v9 bpf-next 9/9] bpf, x86_64: use bpf_jit_binary_pack_alloc Song Liu
2022-02-08 2:24 ` Alexei Starovoitov
2022-07-03 3:02 ` Andres Freund
2022-07-03 3:03 ` Alexei Starovoitov
2022-07-03 3:14 ` Andres Freund
2022-02-08 2:30 ` [PATCH v9 bpf-next 0/9] bpf_prog_pack allocator patchwork-bot+netdevbpf
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