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Merge branch 'bpf-x86-inline-bpf_get_current_task-for-x86_64'

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Menglong Dong says:

====================
bpf, x86: inline bpf_get_current_task() for x86_64

Inline bpf_get_current_task() and bpf_get_current_task_btf() for x86_64
to obtain better performance, and add the testcase for it.

Changes since v5:
* remove unnecessary 'ifdef' and __description in the selftests
* v5: https://lore.kernel.org/bpf/20260119070246.249499-1-dongml2@chinatelecom.cn/

Changes since v4:
* don't support the !CONFIG_SMP case
* v4: https://lore.kernel.org/bpf/20260112104529.224645-1-dongml2@chinatelecom.cn/

Changes since v3:
* handle the !CONFIG_SMP case
* ignore the !CONFIG_SMP case in the testcase, as we enable CONFIG_SMP
  for x86_64 in the selftests

Changes since v2:
* implement it in the verifier with BPF_MOV64_PERCPU_REG() instead of in
  x86_64 JIT (Alexei).

Changes since v1:
* add the testcase
* remove the usage of const_current_task
====================

Link: https://patch.msgid.link/20260120070555.233486-1-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2026-01-20 20:39:01 -08:00
commit ba335bf3a5
3 changed files with 44 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
kernel/bpf/verifier.c
View File

@ -18130,6 +18130,10 @@ 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:
@ -23715,6 +23719,24 @@ 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)&current_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
tools/testing/selftests/bpf/prog_tests/verifier.c
View File

@ -112,6 +112,7 @@
#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
@ -255,6 +256,7 @@ 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)
{

20
tools/testing/selftests/bpf/progs/verifier_jit_inline.c Normal file
View File

@ -0,0 +1,20 @@
// SPDX-License-Identifier: GPL-2.0
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
SEC("fentry/bpf_fentry_test1")
__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;
}
char _license[] SEC("license") = "GPL";