On Thu, 2022-02-03 at 21:23 -0800, Andrii Nakryiko wrote: > On Thu, Feb 3, 2022 at 9:22 PM Andrii Nakryiko > <andrii.nakryiko@xxxxxxxxx> wrote: > > > > On Thu, Feb 3, 2022 at 8:20 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> > > wrote: > > > > > > Some architectures pass a pointer to struct pt_regs to syscall > > > handlers, others unpack it into individual function parameters. > > > Introduce a macro to describe what a particular arch does, using > > > `passing pt_regs *` as a default. > > > > > > Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> > > > --- > > > tools/lib/bpf/bpf_tracing.h | 9 +++++++++ > > > 1 file changed, 9 insertions(+) > > > > > > diff --git a/tools/lib/bpf/bpf_tracing.h > > > b/tools/lib/bpf/bpf_tracing.h > > > index 30f0964f8c9e..400a4f002f77 100644 > > > --- a/tools/lib/bpf/bpf_tracing.h > > > +++ b/tools/lib/bpf/bpf_tracing.h > > > @@ -334,6 +334,15 @@ struct pt_regs; > > > > > > #endif /* defined(bpf_target_defined) */ > > > > > > +/* > > > + * When invoked from a syscall handler kprobe, returns a pointer > > > to a > > > + * struct pt_regs containing syscall arguments and suitable for > > > passing to > > > + * PT_REGS_PARMn_SYSCALL() and PT_REGS_PARMn_CORE_SYSCALL(). > > > + */ > > > +#ifndef PT_REGS_SYSCALL > > > +#define PT_REGS_SYSCALL(ctx) ((struct pt_regs > > > *)PT_REGS_PARM1(ctx)) > > > +#endif > > > > maybe PT_REGS_SYSCALL_REGS? It returns regs, not the "syscall". > > PT_REGS prefix is for consistency with all other pt_regs macros, > > but > > "SYSCALL_REGS" is specifying what is actually returned by the macro > > > > Oh, and instead of casting to `struct pt_regs *` directly, maybe use > __PT_REGS_CAST() instead? For some architectures it probably should > stay user_pt_regs (or whatever it is there). > > > > + > > > #ifndef ___bpf_concat > > > #define ___bpf_concat(a, b) a ## b > > > #endif > > > -- > > > 2.34.1 > > > I think it's better to keep this as struct pt_regs *, so that in bpf progs we can do struct pt_regs *real_regs = PT_REGS_SYSCALL(ctx); without having to worry about which arch we are on, or using the opaque void *.
