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From: Nicholas Piggin <npiggin@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 1/3] powerpc: Split user/kernel definitions of struct pt_regs
Date: Sat, 13 Oct 2018 22:27:56 +1000	[thread overview]
Message-ID: <20181013222756.2e9ca459@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <20181013105646.5147-1-mpe@ellerman.id.au>

On Sat, 13 Oct 2018 21:56:44 +1100
Michael Ellerman <mpe@ellerman.id.au> wrote:

> We use a shared definition for struct pt_regs in uapi/asm/ptrace.h.
> That means the layout of the structure is ABI, ie. we can't change it.
> 
> That would be fine if it was only used to describe the user-visible
> register state of a process, but it's also the struct we use in the
> kernel to describe the registers saved in an interrupt frame.
> 
> We'd like more flexibility in the content (and possibly layout) of the
> kernel version of the struct, but currently that's not possible.
> 
> So split the definition into a user-visible definition which remains
> unchanged, and a kernel internal one.
> 
> At the moment they're still identical, and we check that at build
> time. That's because we have code (in ptrace etc.) that assumes that
> they are the same. We will fix that code in future patches, and then
> we can break the strict symmetry between the two structs.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Yeah this looks much better than my int_frame thing, thanks.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

Thanks,
Nick

  parent reply	other threads:[~2018-10-13 12:31 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-13 10:56 [PATCH 1/3] powerpc: Split user/kernel definitions of struct pt_regs Michael Ellerman
2018-10-13 10:56 ` [PATCH 2/3] powerpc/ptrace: Don't use sizeof(struct pt_regs) in ptrace code Michael Ellerman
2018-10-13 10:56 ` [PATCH 3/3] powerpc/64: Interrupts save PPR on stack rather than thread_struct Michael Ellerman
2018-10-13 12:27 ` Nicholas Piggin [this message]
2018-10-15 12:02   ` [PATCH 1/3] powerpc: Split user/kernel definitions of struct pt_regs Michael Ellerman
2018-10-14  6:36 ` Madhavan Srinivasan
2018-10-15 11:08   ` Michael Ellerman
2018-10-15 12:39     ` Madhavan Srinivasan
2018-10-16 10:50       ` Michael Ellerman
2018-10-15  4:01 ` [1/3] " Michael Ellerman

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