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| author | Jiri Olsa <jolsa@kernel.org> | 2022-10-18 09:59:34 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-10-20 18:57:51 -0700 |
| commit | dbe69b29988465b011f198f2797b1c2b6980b50e (patch) | |
| tree | d060772885a0e15050fe1e1eb96697e61ee25ef3 /arch/x86 | |
| parent | ea68376c8bed5cd156900852aada20c3a0874d17 (diff) | |
| download | linux-dbe69b29988465b011f198f2797b1c2b6980b50e.tar.bz2 | |
bpf: Fix dispatcher patchable function entry to 5 bytes nop
The patchable_function_entry(5) might output 5 single nop
instructions (depends on toolchain), which will clash with
bpf_arch_text_poke check for 5 bytes nop instruction.
Adding early init call for dispatcher that checks and change
the patchable entry into expected 5 nop instruction if needed.
There's no need to take text_mutex, because we are using it
in early init call which is called at pre-smp time.
Fixes: ceea991a019c ("bpf: Move bpf_dispatcher function out of ftrace locations")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221018075934.574415-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 99620428ad78..00127abd89ee 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -11,6 +11,7 @@ #include <linux/bpf.h> #include <linux/memory.h> #include <linux/sort.h> +#include <linux/init.h> #include <asm/extable.h> #include <asm/set_memory.h> #include <asm/nospec-branch.h> @@ -388,6 +389,18 @@ out: return ret; } +int __init bpf_arch_init_dispatcher_early(void *ip) +{ + const u8 *nop_insn = x86_nops[5]; + + if (is_endbr(*(u32 *)ip)) + ip += ENDBR_INSN_SIZE; + + if (memcmp(ip, nop_insn, X86_PATCH_SIZE)) + text_poke_early(ip, nop_insn, X86_PATCH_SIZE); + return 0; +} + int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *old_addr, void *new_addr) { |