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bpf: inline bpf_get_smp_processor_id() helper

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If BPF JIT supports per-CPU MOV instruction, inline bpf_get_smp_processor_id()
to eliminate unnecessary function calls.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20240402021307.1012571-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Andrii Nakryiko 2024-04-01 19:13:03 -07:00 committed by Alexei Starovoitov
parent 7bdbf74463
commit 1ae6921009
1 changed files with 24 additions and 0 deletions
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24
kernel/bpf/verifier.c
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@ -20074,6 +20074,30 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
goto next_insn;
}
#ifdef CONFIG_X86_64
/* Implement bpf_get_smp_processor_id() inline. */
if (insn->imm == BPF_FUNC_get_smp_processor_id &&
prog->jit_requested && bpf_jit_supports_percpu_insn()) {
/* BPF_FUNC_get_smp_processor_id inlining is an
* optimization, so if pcpu_hot.cpu_number is ever
* changed in some incompatible and hard to support
* way, it's fine to back out this inlining logic
*/
insn_buf[0] = BPF_MOV32_IMM(BPF_REG_0, (u32)(unsigned long)&pcpu_hot.cpu_number);
insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0);
insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0);
cnt = 3;
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
if (!new_prog)
return -ENOMEM;
delta += cnt - 1;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
goto next_insn;
}
#endif
/* Implement bpf_get_func_arg inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_arg) {