From: Andrei Vagin <avagin@gmail.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>, Oleg Nesterov <oleg@redhat.com>,
linux-arm-kernel@lists.infradead.org,
LKML <linux-kernel@vger.kernel.org>,
Dave Martin <Dave.Martin@arm.com>,
Keno Fischer <keno@juliacomputing.com>
Subject: Re: [PATCH 1/4] arm64: expose orig_x0 in the user_pt_regs structure
Date: Fri, 26 Mar 2021 17:35:19 -0700 [thread overview]
Message-ID: <CANaxB-xTrMkJ2D19wwjSbCfizdRDnNO52fibpaRXP5g3hOcQwQ@mail.gmail.com> (raw)
In-Reply-To: <20210326182839.GE5126@arm.com>
On Fri, Mar 26, 2021 at 11:28 AM Catalin Marinas
<catalin.marinas@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
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next prev parent reply other threads:[~2021-03-27 0:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 22:50 [PATCH 0/4 v3] arm64/ptrace: allow to get all registers on syscall traps Andrei Vagin
2021-03-22 22:50 ` [PATCH 1/4] arm64: expose orig_x0 in the user_pt_regs structure Andrei Vagin
2021-03-26 18:28 ` Catalin Marinas
2021-03-27 0:35 ` Andrei Vagin [this message]
2021-03-27 13:01 ` Catalin Marinas
2021-03-22 22:50 ` [PATCH 2/4] arm64/ptrace: introduce orig_x7 " Andrei Vagin
2021-03-26 18:39 ` Catalin Marinas
2021-03-22 22:50 ` [PATCH 3/4] selftest/arm64/ptrace: add a test for orig_x0 Andrei Vagin
2021-03-22 22:50 ` [PATCH 4/4] selftest/arm64/ptrace: add a test for orig_x7 Andrei Vagin
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