linux-kernel - Re: [PATCH v3 2/2] powerpc/ptrace: Hard wire PT_SOFTE value to 1 in gpr

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Date:   Tue, 24 Nov 2020 11:53:03 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Oleg Nesterov <oleg@...hat.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Paul Mackerras <paulus@...ba.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Christophe Leroy <christophe.leroy@....fr>,
        Jan Kratochvil <jan.kratochvil@...hat.com>,
        Nicholas Piggin <npiggin@...il.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] powerpc/ptrace: Hard wire PT_SOFTE value to 1 in gpr_get() too

Oleg Nesterov <oleg@...hat.com> writes:
> Christophe, et al,
>
> So what?
>
> Are you going to push your change or should I re-send 1-2 without
> whitespace cleanups?

I'll take your 1 & 2 and fixup the whitespace issues when applying.

cheers

> On 11/19, Oleg Nesterov wrote:
>>
>> On 11/19, Christophe Leroy wrote:
>> >
>> > I think the following should work, and not require the first patch (compile
>> > tested only).
>> >
>> > --- a/arch/powerpc/kernel/ptrace/ptrace-view.c
>> > +++ b/arch/powerpc/kernel/ptrace/ptrace-view.c
>> > @@ -234,9 +234,21 @@ static int gpr_get(struct task_struct *target, const
>> > struct user_regset *regset,
>> >  	BUILD_BUG_ON(offsetof(struct pt_regs, orig_gpr3) !=
>> >  		     offsetof(struct pt_regs, msr) + sizeof(long));
>> > 
>> > +#ifdef CONFIG_PPC64
>> > +	membuf_write(&to, &target->thread.regs->orig_gpr3,
>> > +		     offsetof(struct pt_regs, softe) - offsetof(struct pt_regs,
>> > orig_gpr3));
>> > +	membuf_store(&to, 1UL);
>> > +
>> > +	BUILD_BUG_ON(offsetof(struct pt_regs, trap) !=
>> > +		     offsetof(struct pt_regs, softe) + sizeof(long));
>> > +
>> > +	membuf_write(&to, &target->thread.regs->trap,
>> > +		     sizeof(struct user_pt_regs) - offsetof(struct pt_regs, trap));
>> > +#else
>> >  	membuf_write(&to, &target->thread.regs->orig_gpr3,
>> >  			sizeof(struct user_pt_regs) -
>> >  			offsetof(struct pt_regs, orig_gpr3));
>> > +#endif
>> >  	return membuf_zero(&to, ELF_NGREG * sizeof(unsigned long) -
>> >  				 sizeof(struct user_pt_regs));
>> >  }
>> 
>> Probably yes.
>> 
>> This mirrors the previous patch I sent (https://lore.kernel.org/lkml/20190917143753.GA12300@redhat.com/)
>> and this is exactly what I tried to avoid, we can make a simpler fix now.
>> 
>> But let me repeat, I agree with any fix even if imp my version simplifies the code, just
>> commit this change and lets forget this problem.
>> 
>> Oleg.