diff options
| 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 /kernel/bpf | |
| 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 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/core.c | 11 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 4 |
2 files changed, 15 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 99b8b1c9a248..aa59af9f9bd9 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2941,6 +2941,17 @@ bool __weak bpf_jit_needs_zext(void) return false; } +/* Return true if the JIT inlines the call to the helper corresponding to + * the imm. + * + * The verifier will not patch the insn->imm for the call to the helper if + * this returns true. + */ +bool __weak bpf_jit_inlines_helper_call(s32 imm) +{ + return false; +} + /* Return TRUE if the JIT backend supports mixing bpf2bpf and tailcalls. */ bool __weak bpf_jit_supports_subprog_tailcalls(void) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9e3aba08984e..1658ca4136a3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19996,6 +19996,10 @@ static int do_misc_fixups(struct bpf_verifier_env *env) goto next_insn; } + /* Skip inlining the helper call if the JIT does it. */ + if (bpf_jit_inlines_helper_call(insn->imm)) + goto next_insn; + if (insn->imm == BPF_FUNC_get_route_realm) prog->dst_needed = 1; if (insn->imm == BPF_FUNC_get_prandom_u32) |