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authorPuranjay Mohan <puranjay@kernel.org>2024-05-02 15:18:54 +0000
committerAlexei Starovoitov <ast@kernel.org>2024-05-12 16:54:34 -0700
commit75fe4c0b3e181f5e3b990128013ac192fdfd4012 (patch)
treefd23f2dc376d2db2d93c1831ad0abae58eb0868e /arch
parent7a4c32222b0e14349a6311e72bf6ebd3e1d1064b (diff)
bpf, arm64: inline bpf_get_smp_processor_id() helper
Inline calls to bpf_get_smp_processor_id() helper in the JIT by emitting a read from struct thread_info. The SP_EL0 system register holds the pointer to the task_struct and thread_info is the first member of this struct. We can read the cpu number from the thread_info. Here is how the ARM64 JITed assembly changes after this commit: ARM64 JIT =========== BEFORE AFTER -------- ------- int cpu = bpf_get_smp_processor_id(); int cpu = bpf_get_smp_processor_id(); mov x10, #0xfffffffffffff4d0 mrs x10, sp_el0 movk x10, #0x802b, lsl #16 ldr w7, [x10, #24] movk x10, #0x8000, lsl #32 blr x10 add x7, x0, #0x0 Performance improvement using benchmark[1] ./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc +---------------+-------------------+-------------------+--------------+ | Name | Before | After | % change | |---------------+-------------------+-------------------+--------------| | glob-arr-inc | 23.380 ± 1.675M/s | 25.893 ± 0.026M/s | + 10.74% | | arr-inc | 23.928 ± 0.034M/s | 25.213 ± 0.063M/s | + 5.37% | | hash-inc | 12.352 ± 0.005M/s | 12.609 ± 0.013M/s | + 2.08% | +---------------+-------------------+-------------------+--------------+ [1] https://github.com/anakryiko/linux/commit/8dec900975ef Signed-off-by: Puranjay Mohan <puranjay@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20240502151854.9810-5-puranjay@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/include/asm/insn.h1
-rw-r--r--arch/arm64/net/bpf_jit.h2
-rw-r--r--arch/arm64/net/bpf_jit_comp.c25
3 files changed, 28 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index 8de0e39b29f3..8c0a36f72d6f 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -138,6 +138,7 @@ enum aarch64_insn_special_register {
enum aarch64_insn_system_register {
AARCH64_INSN_SYSREG_TPIDR_EL1 = 0x4684,
AARCH64_INSN_SYSREG_TPIDR_EL2 = 0x6682,
+ AARCH64_INSN_SYSREG_SP_EL0 = 0x4208,
};
enum aarch64_insn_variant {
diff --git a/arch/arm64/net/bpf_jit.h b/arch/arm64/net/bpf_jit.h
index b627ef7188c7..b22ab2f97a30 100644
--- a/arch/arm64/net/bpf_jit.h
+++ b/arch/arm64/net/bpf_jit.h
@@ -302,5 +302,7 @@
aarch64_insn_gen_mrs(Rt, AARCH64_INSN_SYSREG_TPIDR_EL1)
#define A64_MRS_TPIDR_EL2(Rt) \
aarch64_insn_gen_mrs(Rt, AARCH64_INSN_SYSREG_TPIDR_EL2)
+#define A64_MRS_SP_EL0(Rt) \
+ aarch64_insn_gen_mrs(Rt, AARCH64_INSN_SYSREG_SP_EL0)
#endif /* _BPF_JIT_H */
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 4e7954e9829d..47151414a450 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -1228,6 +1228,21 @@ emit_cond_jmp:
const u8 r0 = bpf2a64[BPF_REG_0];
bool func_addr_fixed;
u64 func_addr;
+ u32 cpu_offset;
+
+ /* Implement helper call to bpf_get_smp_processor_id() inline */
+ if (insn->src_reg == 0 && insn->imm == BPF_FUNC_get_smp_processor_id) {
+ cpu_offset = offsetof(struct thread_info, cpu);
+
+ emit(A64_MRS_SP_EL0(tmp), ctx);
+ if (is_lsi_offset(cpu_offset, 2)) {
+ emit(A64_LDR32I(r0, tmp, cpu_offset), ctx);
+ } else {
+ emit_a64_mov_i(1, tmp2, cpu_offset, ctx);
+ emit(A64_LDR32(r0, tmp, tmp2), ctx);
+ }
+ break;
+ }
ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass,
&func_addr, &func_addr_fixed);
@@ -2573,6 +2588,16 @@ bool bpf_jit_supports_percpu_insn(void)
return true;
}
+bool bpf_jit_inlines_helper_call(s32 imm)
+{
+ switch (imm) {
+ case BPF_FUNC_get_smp_processor_id:
+ return true;
+ default:
+ return false;
+ }
+}
+
void bpf_jit_free(struct bpf_prog *prog)
{
if (prog->jited) {