On Fri, Mar 26, 2021 at 11:28 AM Catalin Marinas <catalin.mari...@arm.com> wrote: > > On Mon, Mar 22, 2021 at 03:50:50PM -0700, Andrei Vagin wrote: > > diff --git a/arch/arm64/include/uapi/asm/ptrace.h > > b/arch/arm64/include/uapi/asm/ptrace.h > > index 758ae984ff97..3c118c5b0893 100644 > > --- a/arch/arm64/include/uapi/asm/ptrace.h > > +++ b/arch/arm64/include/uapi/asm/ptrace.h > > @@ -90,6 +90,7 @@ struct user_pt_regs { > > __u64 sp; > > __u64 pc; > > __u64 pstate; > > + __u64 orig_x0; > > }; > > That's a UAPI change, likely to go wrong. For example, a > ptrace(PTRACE_GETREGSET, pid, REGSET_GPR, data) would write past the end > of an old struct user_pt_regs in the debugger.
ptrace(PTRACE_GETREGSET, ...) receives iovec: ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov) iov contains a pointer to a buffer and its size and the kernel fills only the part that fits the buffer. I think this interface was invented to allow extending structures without breaking backward compatibility. > > -- > Catalin