Re: [PATCH bpf-next v4 2/2] powerpc64/bpf: Inline bpf_get_smp_processor_id() and bpf_get_current_task/_btf()
From: Hari Bathini <hbathini@linux.ibm.com>
Date: 2025-12-17 05:13:08
Also in:
bpf, lkml
On 10/12/25 12:20 pm, Saket Kumar Bhaskar wrote:
Inline the calls to bpf_get_smp_processor_id() and bpf_get_current_task/_btf() in the powerpc bpf jit. powerpc saves the Logical processor number (paca_index) and pointer to current task (__current) in paca. Here is how the powerpc JITed assembly changes after this commit: Before: cpu = bpf_get_smp_processor_id(); addis 12, 2, -517 addi 12, 12, -29456 mtctr 12 bctrl mr 8, 3 After: cpu = bpf_get_smp_processor_id(); lhz 8, 8(13) To evaluate the performance improvements introduced by this change, the benchmark described in [1] was employed. +---------------+-------------------+-------------------+--------------+ | Name | Before | After | % change | |---------------+-------------------+-------------------+--------------| | glob-arr-inc | 40.701 ± 0.008M/s | 55.207 ± 0.021M/s | + 35.64% | | arr-inc | 39.401 ± 0.007M/s | 56.275 ± 0.023M/s | + 42.42% | | hash-inc | 24.944 ± 0.004M/s | 26.212 ± 0.003M/s | + 5.08% | +---------------+-------------------+-------------------+--------------+ [1] https://github.com/anakryiko/linux/commit/8dec900975ef
Looks good. Acked-by: Hari Bathini <hbathini@linux.ibm.com>
quoted hunk ↗ jump to hunk
Reviewed-by: Puranjay Mohan <puranjay@kernel.org> Signed-off-by: Saket Kumar Bhaskar <redacted> --- arch/powerpc/net/bpf_jit_comp.c | 12 ++++++++++++ arch/powerpc/net/bpf_jit_comp64.c | 11 +++++++++++ 2 files changed, 23 insertions(+)diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index d53e9cd7563f..b243ee205885 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c@@ -471,6 +471,18 @@ bool bpf_jit_supports_percpu_insn(void) return IS_ENABLED(CONFIG_PPC64); } +bool bpf_jit_inlines_helper_call(s32 imm) +{ + switch (imm) { + case BPF_FUNC_get_smp_processor_id: + case BPF_FUNC_get_current_task: + case BPF_FUNC_get_current_task_btf: + return true; + default: + return false; + } +} + void *arch_alloc_bpf_trampoline(unsigned int size) { return bpf_prog_pack_alloc(size, bpf_jit_fill_ill_insns);diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 37723ee9344e..6c827e7aa691 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c@@ -1400,6 +1400,17 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code case BPF_JMP | BPF_CALL: ctx->seen |= SEEN_FUNC; + if (src_reg == bpf_to_ppc(BPF_REG_0)) { + if (imm == BPF_FUNC_get_smp_processor_id) { + EMIT(PPC_RAW_LHZ(src_reg, _R13, offsetof(struct paca_struct, paca_index))); + break; + } else if (imm == BPF_FUNC_get_current_task || + imm == BPF_FUNC_get_current_task_btf) { + EMIT(PPC_RAW_LD(src_reg, _R13, offsetof(struct paca_struct, __current))); + break; + } + } + ret = bpf_jit_get_func_addr(fp, &insn[i], extra_pass, &func_addr, &func_addr_fixed); if (ret < 0)