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| author | Puranjay Mohan <puranjay@kernel.org> | 2024-05-02 15:18:52 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-05-12 16:54:34 -0700 |
| commit | 2ddec2c80b4402c293c7e6e0881cecaaf77e8cec (patch) | |
| tree | 89aee6a00fc8312f43c2fae605a8e0a4c9062721 /arch | |
| parent | 19c56d4e5be102cd118162b9f72d9c6d353e76fc (diff) | |
riscv, bpf: inline bpf_get_smp_processor_id()
Inline the calls to bpf_get_smp_processor_id() in the riscv bpf jit.
RISCV saves the pointer to the CPU's task_struct in the TP (thread
pointer) register. This makes it trivial to get the CPU's processor id.
As thread_info is the first member of task_struct, we can read the
processor id from TP + offsetof(struct thread_info, cpu).
RISCV64 JIT output for `call bpf_get_smp_processor_id`
======================================================
Before After
-------- -------
auipc t1,0x848c ld a5,32(tp)
jalr 604(t1)
mv a5,a0
Benchmark using [1] on Qemu.
./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc
+---------------+------------------+------------------+--------------+
| Name | Before | After | % change |
|---------------+------------------+------------------+--------------|
| glob-arr-inc | 1.077 ± 0.006M/s | 1.336 ± 0.010M/s | + 24.04% |
| arr-inc | 1.078 ± 0.002M/s | 1.332 ± 0.015M/s | + 23.56% |
| hash-inc | 0.494 ± 0.004M/s | 0.653 ± 0.001M/s | + 32.18% |
+---------------+------------------+------------------+--------------+
NOTE: This benchmark includes changes from this patch and the previous
patch that implemented the per-cpu insn.
[1] https://github.com/anakryiko/linux/commit/8dec900975ef
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/r/20240502151854.9810-3-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/riscv/net/bpf_jit_comp64.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 1f0159963b3e..a46ec7fb4489 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -1493,6 +1493,22 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, bool fixed_addr; u64 addr; + /* Inline calls to bpf_get_smp_processor_id() + * + * RV_REG_TP holds the address of the current CPU's task_struct and thread_info is + * at offset 0 in task_struct. + * Load cpu from thread_info: + * Set R0 to ((struct thread_info *)(RV_REG_TP))->cpu + * + * This replicates the implementation of raw_smp_processor_id() on RISCV + */ + if (insn->src_reg == 0 && insn->imm == BPF_FUNC_get_smp_processor_id) { + /* Load current CPU number in R0 */ + emit_ld(bpf_to_rv_reg(BPF_REG_0, ctx), offsetof(struct thread_info, cpu), + RV_REG_TP, ctx); + break; + } + mark_call(ctx); ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass, &addr, &fixed_addr); @@ -2062,3 +2078,13 @@ 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; + } +} |