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Sun, 04 Jan 2026 05:17:04 -0800 (PST) From: Menglong Dong X-Google-Original-From: Menglong Dong To: ast@kernel.org, eddyz87@gmail.com Cc: davem@davemloft.net, dsahern@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf-next v2 1/2] bpf, x86: inline bpf_get_current_task() for x86_64 Date: Sun, 4 Jan 2026 21:16:34 +0800 Message-ID: <20260104131635.27621-2-dongml2@chinatelecom.cn> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260104131635.27621-1-dongml2@chinatelecom.cn> References: <20260104131635.27621-1-dongml2@chinatelecom.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Inline bpf_get_current_task() and bpf_get_current_task_btf() for x86_64 to obtain better performance. The instruction we use here is: 65 48 8B 04 25 [offset] // mov rax, gs:[offset] Signed-off-by: Menglong Dong --- v2: - check the variable type in emit_ldx_percpu_r0 with __verify_pcpu_ptr - remove the usage of const_current_task --- arch/x86/net/bpf_jit_comp.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index e3b1c4b1d550..f5ff7c77aad7 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -1300,6 +1300,25 @@ static void emit_st_r12(u8 **pprog, u32 size, u32 ds= t_reg, int off, int imm) emit_st_index(pprog, size, dst_reg, X86_REG_R12, off, imm); } =20 +static void __emit_ldx_percpu_r0(u8 **pprog, __force unsigned long ptr) +{ + u8 *prog =3D *pprog; + + /* mov rax, gs:[ptr] */ + EMIT2(0x65, 0x48); + EMIT2(0x8B, 0x04); + EMIT1(0x25); + EMIT((u32)ptr, 4); + + *pprog =3D prog; +} + +#define emit_ldx_percpu_r0(prog, variable) \ + do { \ + __verify_pcpu_ptr(&(variable)); 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Sun, 04 Jan 2026 05:17:15 -0800 (PST) Received: from 7950hx ([160.187.0.149]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-34f4777b765sm3701582a91.17.2026.01.04.05.17.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jan 2026 05:17:15 -0800 (PST) From: Menglong Dong X-Google-Original-From: Menglong Dong To: ast@kernel.org, eddyz87@gmail.com Cc: davem@davemloft.net, dsahern@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf-next v2 2/2] selftests/bpf: test the jited inline of bpf_get_current_task Date: Sun, 4 Jan 2026 21:16:35 +0800 Message-ID: <20260104131635.27621-3-dongml2@chinatelecom.cn> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260104131635.27621-1-dongml2@chinatelecom.cn> References: <20260104131635.27621-1-dongml2@chinatelecom.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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/test= ing/selftests/bpf/prog_tests/verifier.c index 5829ffd70f8f..47eb78c808c0 100644 --- a/tools/testing/selftests/bpf/prog_tests/verifier.c +++ b/tools/testing/selftests/bpf/prog_tests/verifier.c @@ -110,6 +110,7 @@ #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" =20 #define MAX_ENTRIES 11 @@ -251,6 +252,7 @@ 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_inlin= e); } =20 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/tool= s/testing/selftests/bpf/progs/verifier_jit_inline.c new file mode 100644 index 000000000000..398a6405d00a --- /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(" movq %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") =3D "GPL"; --=20 2.52.0