diff options
| author | Leon Hwang <hffilwlqm@gmail.com> | 2024-01-04 22:22:23 +0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-01-04 20:22:10 -0800 |
| commit | 00bc8988807985e32f5103f1ac099baf593bd8a3 (patch) | |
| tree | d649b54630cb71b10e84e48ebb281a36a0253ac0 /arch/x86/net/bpf_jit_comp.c | |
| parent | 61a40c12496a763fdb95edc08d59f816a594a87a (diff) | |
bpf, x86: Use emit_nops to replace memcpy x86_nops
Move emit_nops() before emit_prologue() and replace
memcpy(prog, x86_nops[5], X86_PATCH_SIZE) with emit_nops(&prog, X86_PATCH_SIZE).
Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
Link: https://lore.kernel.org/r/20240104142226.87869-2-hffilwlqm@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 47 |
1 files changed, 22 insertions, 25 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index bdacbb84456d..fe30b9ebb8de 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -307,6 +307,25 @@ static void pop_callee_regs(u8 **pprog, bool *callee_regs_used) *pprog = prog; } +static void emit_nops(u8 **pprog, int len) +{ + u8 *prog = *pprog; + int i, noplen; + + while (len > 0) { + noplen = len; + + if (noplen > ASM_NOP_MAX) + noplen = ASM_NOP_MAX; + + for (i = 0; i < noplen; i++) + EMIT1(x86_nops[noplen][i]); + len -= noplen; + } + + *pprog = prog; +} + /* * Emit the various CFI preambles, see asm/cfi.h and the comments about FineIBT * in arch/x86/kernel/alternative.c @@ -385,8 +404,7 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf, /* BPF trampoline can be made to work without these nops, * but let's waste 5 bytes for now and optimize later */ - memcpy(prog, x86_nops[5], X86_PATCH_SIZE); - prog += X86_PATCH_SIZE; + emit_nops(&prog, X86_PATCH_SIZE); if (!ebpf_from_cbpf) { if (tail_call_reachable && !is_subprog) /* When it's the entry of the whole tailcall context, @@ -692,8 +710,7 @@ static void emit_bpf_tail_call_direct(struct bpf_prog *bpf_prog, if (stack_depth) EMIT3_off32(0x48, 0x81, 0xC4, round_up(stack_depth, 8)); - memcpy(prog, x86_nops[5], X86_PATCH_SIZE); - prog += X86_PATCH_SIZE; + emit_nops(&prog, X86_PATCH_SIZE); /* out: */ ctx->tail_call_direct_label = prog - start; @@ -1055,25 +1072,6 @@ static void detect_reg_usage(struct bpf_insn *insn, int insn_cnt, } } -static void emit_nops(u8 **pprog, int len) -{ - u8 *prog = *pprog; - int i, noplen; - - while (len > 0) { - noplen = len; - - if (noplen > ASM_NOP_MAX) - noplen = ASM_NOP_MAX; - - for (i = 0; i < noplen; i++) - EMIT1(x86_nops[noplen][i]); - len -= noplen; - } - - *pprog = prog; -} - /* emit the 3-byte VEX prefix * * r: same as rex.r, extra bit for ModRM reg field @@ -2700,8 +2698,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im /* 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 = image + (prog - (u8 *)rw_image); - memcpy(prog, x86_nops[5], X86_PATCH_SIZE); - prog += X86_PATCH_SIZE; + emit_nops(&prog, X86_PATCH_SIZE); } if (fmod_ret->nr_links) { |