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Merge branch 'risc-v-jit-support-for-bpf_get_current_task-_btf'

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Varun R Mallya says:

====================
RISC-V JIT support for bpf_get_current_task/_btf

These two patches add support for the bpf_get_current_task and
bpf_get_current_task_btf kfuncs in RISC-V JIT and add a selftest.

The first patch adds support for cpu and feature detection on
the JIT disassembly helper function as RISC-V JITed code was not
being disassembled using `LLVMCreateDisasm` as it was missing the
"+c" CPU feature and JITed code contained RISC-V Compressed (C)
Extension. This patch generalizes that to detect CPU features and
enables testing on more RISC-V JIT work ahead.

The second patch, which actually adds this support has been benchmarked
on QEMU RISC-V and shows significant improvements.
It was benchmarked using a simple loop inside a bpf program that ran
bpf_get_current_task() and execution time was measured. It used
bpf_prog_test_run_opts() to repeatedly trigger the BPF program. The loop
ran in 1 second intervals and it kept firing bpf_prog_test_run_opts() as
fast as possible until a second had elapsed and then reported statistics.
====================

Link: https://patch.msgid.link/20260602205847.102825-1-varunrmallya@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2026-06-05 15:26:18 -07:00
commit b984529052
3 changed files with 22 additions and 2 deletions
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9
arch/riscv/net/bpf_jit_comp64.c
View File

@ -1808,6 +1808,13 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
break;
}
/* Implement helper call to bpf_get_current_task/_btf() inline */
if (insn->src_reg == 0 && (insn->imm == BPF_FUNC_get_current_task ||
insn->imm == BPF_FUNC_get_current_task_btf)) {
emit_mv(bpf_to_rv_reg(BPF_REG_0, ctx), RV_REG_TP, ctx);
break;
}
mark_call(ctx);
ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass,
&addr, &fixed_addr);
@ -2138,6 +2145,8 @@ 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;

13
tools/testing/selftests/bpf/jit_disasm_helpers.c
View File

@ -96,10 +96,19 @@ static int disasm_one_func(FILE *text_out, uint8_t *image, __u32 len)
__u32 *label_pc, pc;
int i, cnt, err = 0;
char buf[64];
char *cpu, *features;
triple = LLVMGetDefaultTargetTriple();
ctx = LLVMCreateDisasm(triple, &labels, 0, NULL, lookup_symbol);
if (!ASSERT_OK_PTR(ctx, "LLVMCreateDisasm")) {
cpu = LLVMGetHostCPUName();
features = LLVMGetHostCPUFeatures();
ctx = LLVMCreateDisasmCPUFeatures(triple, cpu, features, &labels, 0, NULL, lookup_symbol);
LLVMDisposeMessage(cpu);
LLVMDisposeMessage(features);
if (!ASSERT_OK_PTR(ctx, "LLVMCreateDisasmCPUFeatures")) {
err = -EINVAL;
goto out;
}

2
tools/testing/selftests/bpf/progs/verifier_jit_inline.c
View File

@ -10,6 +10,8 @@ __arch_x86_64
__jited(" addq %gs:{{.*}}, %rax")
__arch_arm64
__jited(" mrs x8, SP_EL0")
__arch_riscv64
__jited(" mv a5, tp")
int inline_bpf_get_current_task(void)
{
bpf_get_current_task();