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 <[email protected]>
Reviewed-by: Puranjay Mohan <[email protected]>
Signed-off-by: Saket Kumar Bhaskar <[email protected]>
---
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)
