diff options
| author | Stanislav Fomichev <sdf@google.com> | 2021-03-19 17:00:01 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-03-19 19:25:39 -0700 |
| commit | b9082970478009b778aa9b22d5561eef35b53b63 (patch) | |
| tree | c94b34dac36e81130d41eae939186180de7eaedb /arch/x86/net | |
| parent | f60a85cad677c4f9bb4cadd764f1d106c38c7cf8 (diff) | |
bpf: Use NOP_ATOMIC5 instead of emit_nops(&prog, 5) for BPF_TRAMP_F_CALL_ORIG
__bpf_arch_text_poke does rewrite only for atomic nop5, emit_nops(xxx, 5)
emits non-atomic one which breaks fentry/fexit with k8 atomics:
P6_NOP5 == P6_NOP5_ATOMIC (0f1f440000 == 0f1f440000)
K8_NOP5 != K8_NOP5_ATOMIC (6666906690 != 6666666690)
Can be reproduced by doing "ideal_nops = k8_nops" in "arch_init_ideal_nops()
and running fexit_bpf2bpf selftest.
Fixes: e21aa341785c ("bpf: Fix fexit trampoline.")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210320000001.915366-1-sdf@google.com
Diffstat (limited to 'arch/x86/net')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 72b5a57e9e31..b35fc8023884 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2012,7 +2012,8 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i /* remember return value in a stack for bpf prog to access */ emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8); im->ip_after_call = prog; - emit_nops(&prog, 5); + memcpy(prog, ideal_nops[NOP_ATOMIC5], X86_PATCH_SIZE); + prog += X86_PATCH_SIZE; } if (fmod_ret->nr_progs) { |