[PATCH v2 bpf-next 5/7] x86/alternative: introduce text_poke_jit
flat view
STALE1761d
SUPERSEDED
From: Song Liu <song@kernel.org>
Date: 2021-12-15 06:01:33
Also in:
bpf, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Revision v2 of 8 in this series.
Revisions (8)
This will be used by BPF jit compiler to dump JITed binary to a RWX huge page, and thus allow multiple BPF programs sharing the a huge (2MB) page. Signed-off-by: Song Liu <song@kernel.org> --- arch/x86/include/asm/text-patching.h | 1 + arch/x86/kernel/alternative.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+)
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index b7421780e4e9..991058c9b4b1 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_jit(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 23fb4d51a5da..02c35725cc62 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c@@ -1102,6 +1102,34 @@ void *text_poke_kgdb(void *addr, const void *opcode, size_t len) return __text_poke(addr, opcode, len); } +/** + * text_poke_jit - Update instructions on a live kernel by jit engine + * @addr: address to modify + * @opcode: source of the copy + * @len: length to copy, could be more than 2x PAGE_SIZE + * + * Only module memory taking jit text (e.g. for bpf) should be patched. + */ +void *text_poke_jit(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; + + 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; + } + return addr; +} + static void do_sync_core(void *info) { sync_core();
--
2.30.2