On Mon, Dec 10, 2018 at 03:11:07PM +0100, Oleg Nesterov wrote:
> On 12/10, Dmitry V. Levin wrote:
> >
> > +struct ptrace_syscall_info {
> > + __u8 op; /* PTRACE_SYSCALL_INFO_* */
> > + __u8 __pad0[3];
> > + __u32 arch;
> > + __u64 instruction_pointer;
> > + __u64 stack_pointer;
> > + __u64 frame_pointer;
> > + union {
> > + struct {
> > + __u64 nr;
> > + __u64 args[6];
> > + } entry;
> > + struct {
> > + __s64 rval;
> > + __u8 is_error;
> > + __u8 __pad1[7];
> > + } exit;
> > + struct {
> > + __u64 nr;
> > + __u64 args[6];
> > + __u32 ret_data;
> > + __u8 __pad2[4];
> > + } seccomp;
> > + };
> > +};
>
> Could you explain why ptrace_syscall_info needs __pad{0,1,2} ? I simply can't
> understand why...I suppose the idea behind the use of these pads was to make the structure arch-independent. I don't think we really need to keep it exactly the same on all architectures - the only practical requirement is to avoid any compat issues, but I don't mind keeping the structure arch-independent. -- ldv
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