Inline bpf_get_current_task() and bpf_get_current_task_btf() for x86_64 to obtain better performance. In !CONFIG_SMP case, the percpu variable is just a normal variable, and we can read the current_task directly. Signed-off-by: Menglong Dong --- v5: - don't support the !CONFIG_SMP case v4: - handle the !CONFIG_SMP case v3: - implement it in the verifier with BPF_MOV64_PERCPU_REG() instead of in x86_64 JIT. --- kernel/bpf/verifier.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9de0ec0c3ed9..c4e2ffadfb1f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -17739,6 +17739,10 @@ static bool verifier_inlines_helper_call(struct bpf_verifier_env *env, s32 imm) switch (imm) { #ifdef CONFIG_X86_64 case BPF_FUNC_get_smp_processor_id: +#ifdef CONFIG_SMP + case BPF_FUNC_get_current_task_btf: + case BPF_FUNC_get_current_task: +#endif return env->prog->jit_requested && bpf_jit_supports_percpu_insn(); #endif default: @@ -23319,6 +23323,24 @@ static int do_misc_fixups(struct bpf_verifier_env *env) insn = new_prog->insnsi + i + delta; goto next_insn; } + + /* Implement bpf_get_current_task() and bpf_get_current_task_btf() inline. */ + if ((insn->imm == BPF_FUNC_get_current_task || insn->imm == BPF_FUNC_get_current_task_btf) && + verifier_inlines_helper_call(env, insn->imm)) { + insn_buf[0] = BPF_MOV64_IMM(BPF_REG_0, (u32)(unsigned long)¤t_task); + insn_buf[1] = BPF_MOV64_PERCPU_REG(BPF_REG_0, BPF_REG_0); + insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 0); + cnt = 3; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + goto next_insn; + } #endif /* Implement bpf_get_func_arg inline. */ if (prog_type == BPF_PROG_TYPE_TRACING && -- 2.52.0 Add the testcase for the jited inline of bpf_get_current_task(). Signed-off-by: Menglong Dong --- .../selftests/bpf/prog_tests/verifier.c | 2 ++ .../selftests/bpf/progs/verifier_jit_inline.c | 35 +++++++++++++++++++ 2 files changed, 37 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/verifier_jit_inline.c diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c index 38c5ba70100c..2ae7b096bd64 100644 --- a/tools/testing/selftests/bpf/prog_tests/verifier.c +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c @@ -111,6 +111,7 @@ #include "verifier_xdp_direct_packet_access.skel.h" #include "verifier_bits_iter.skel.h" #include "verifier_lsm.skel.h" +#include "verifier_jit_inline.skel.h" #include "irq.skel.h" #define MAX_ENTRIES 11 @@ -253,6 +254,7 @@ void test_verifier_bits_iter(void) { RUN(verifier_bits_iter); } void test_verifier_lsm(void) { RUN(verifier_lsm); } void test_irq(void) { RUN(irq); } void test_verifier_mtu(void) { RUN(verifier_mtu); } +void test_verifier_jit_inline(void) { RUN(verifier_jit_inline); } static int init_test_val_map(struct bpf_object *obj, char *map_name) { diff --git a/tools/testing/selftests/bpf/progs/verifier_jit_inline.c b/tools/testing/selftests/bpf/progs/verifier_jit_inline.c new file mode 100644 index 000000000000..0938ca1dac87 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/verifier_jit_inline.c @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include "bpf_misc.h" + +#if defined(__TARGET_ARCH_x86) || defined(__TARGET_ARCH_arm64) + +SEC("fentry/bpf_fentry_test1") +__description("Jit inline, bpf_get_current_task") +__success __retval(0) +__arch_x86_64 +__jited(" addq %gs:{{.*}}, %rax") +__arch_arm64 +__jited(" mrs x7, SP_EL0") +int inline_bpf_get_current_task(void) +{ + bpf_get_current_task(); + + return 0; +} + +#else + +SEC("kprobe") +__description("Jit inline is not supported, use a dummy test") +__success +int dummy_test(void) +{ + return 0; +} + +#endif + +char _license[] SEC("license") = "GPL"; -- 2.52.0