diff options
| author | Hengqi Chen <hengqi.chen@gmail.com> | 2022-02-07 17:31:33 +0300 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2022-02-09 08:45:02 +0300 |
| commit | 816ae109554756ce5e22e3aabde10161c4d0a4f7 (patch) | |
| tree | 09215447fd16ddd4375d741116f8ca26aad4b332 | |
| parent | 8dd039a6fcf3ff559a49533bbc6433c63b53c41c (diff) | |
| download | linux-816ae109554756ce5e22e3aabde10161c4d0a4f7.tar.xz | |
libbpf: Add BPF_KPROBE_SYSCALL macro
Add syscall-specific variant of BPF_KPROBE named BPF_KPROBE_SYSCALL ([0]).
The new macro hides the underlying way of getting syscall input arguments.
With the new macro, the following code:
SEC("kprobe/__x64_sys_close")
int BPF_KPROBE(do_sys_close, struct pt_regs *regs)
{
int fd;
fd = PT_REGS_PARM1_CORE(regs);
/* do something with fd */
}
can be written as:
SEC("kprobe/__x64_sys_close")
int BPF_KPROBE_SYSCALL(do_sys_close, int fd)
{
/* do something with fd */
}
[0] Closes: https://github.com/libbpf/libbpf/issues/425
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220207143134.2977852-2-hengqi.chen@gmail.com
| -rw-r--r-- | tools/lib/bpf/bpf_tracing.h | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/tools/lib/bpf/bpf_tracing.h b/tools/lib/bpf/bpf_tracing.h index eb6eb3b28063..e3a8c947e89f 100644 --- a/tools/lib/bpf/bpf_tracing.h +++ b/tools/lib/bpf/bpf_tracing.h @@ -470,4 +470,39 @@ typeof(name(0)) name(struct pt_regs *ctx) \ } \ static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args) +#define ___bpf_syscall_args0() ctx +#define ___bpf_syscall_args1(x) ___bpf_syscall_args0(), (void *)PT_REGS_PARM1_CORE_SYSCALL(regs) +#define ___bpf_syscall_args2(x, args...) ___bpf_syscall_args1(args), (void *)PT_REGS_PARM2_CORE_SYSCALL(regs) +#define ___bpf_syscall_args3(x, args...) ___bpf_syscall_args2(args), (void *)PT_REGS_PARM3_CORE_SYSCALL(regs) +#define ___bpf_syscall_args4(x, args...) ___bpf_syscall_args3(args), (void *)PT_REGS_PARM4_CORE_SYSCALL(regs) +#define ___bpf_syscall_args5(x, args...) ___bpf_syscall_args4(args), (void *)PT_REGS_PARM5_CORE_SYSCALL(regs) +#define ___bpf_syscall_args(args...) ___bpf_apply(___bpf_syscall_args, ___bpf_narg(args))(args) + +/* + * BPF_KPROBE_SYSCALL is a variant of BPF_KPROBE, which is intended for + * tracing syscall functions, like __x64_sys_close. It hides the underlying + * platform-specific low-level way of getting syscall input arguments from + * struct pt_regs, and provides a familiar typed and named function arguments + * syntax and semantics of accessing syscall input parameters. + * + * Original struct pt_regs* context is preserved as 'ctx' argument. This might + * be necessary when using BPF helpers like bpf_perf_event_output(). + * + * This macro relies on BPF CO-RE support. + */ +#define BPF_KPROBE_SYSCALL(name, args...) \ +name(struct pt_regs *ctx); \ +static __attribute__((always_inline)) typeof(name(0)) \ +____##name(struct pt_regs *ctx, ##args); \ +typeof(name(0)) name(struct pt_regs *ctx) \ +{ \ + struct pt_regs *regs = PT_REGS_SYSCALL_REGS(ctx); \ + _Pragma("GCC diagnostic push") \ + _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ + return ____##name(___bpf_syscall_args(args)); \ + _Pragma("GCC diagnostic pop") \ +} \ +static __attribute__((always_inline)) typeof(name(0)) \ +____##name(struct pt_regs *ctx, ##args) + #endif |