linux-kernel - Re: [PATCH? v2] powerpc: Hard wire PT_SOFTE value to 1 in gpr

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Date:   Wed, 10 Jun 2020 17:07:03 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Mackerras <paulus@...ba.org>
Cc:     Jan Kratochvil <jan.kratochvil@...hat.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH? v2] powerpc: Hard wire PT_SOFTE value to 1 in gpr_get()
 too

Hi,

looks like this patch was forgotten.

Do you think this should be fixed or should we document that
PTRACE_GETREGS is not consistent with PTRACE_PEEKUSER on ppc64?


On 09/17, Oleg Nesterov wrote:
>
> I don't have a ppc machine, this patch wasn't even compile tested,
> could you please review?
> 
> The commit a8a4b03ab95f ("powerpc: Hard wire PT_SOFTE value to 1 in
> ptrace & signals") changed ptrace_get_reg(PT_SOFTE) to report 0x1,
> but PTRACE_GETREGS still copies pt_regs->softe as is.
> 
> This is not consistent and this breaks
> http://sourceware.org/systemtap/wiki/utrace/tests/user-regs-peekpoke
> 
> Reported-by: Jan Kratochvil <jan.kratochvil@...hat.com>
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---
>  arch/powerpc/kernel/ptrace.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
> index 8c92feb..291acfb 100644
> --- a/arch/powerpc/kernel/ptrace.c
> +++ b/arch/powerpc/kernel/ptrace.c
> @@ -363,11 +363,36 @@ 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
> +	if (!ret)
> +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> +					  &target->thread.regs->orig_gpr3,
> +					  offsetof(struct pt_regs, orig_gpr3),
> +					  offsetof(struct pt_regs, softe));
> +
> +	if (!ret) {
> +		unsigned long softe = 0x1;
> +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &softe,
> +					  offsetof(struct pt_regs, softe),
> +					  offsetof(struct pt_regs, softe) +
> +					  sizeof(softe));
> +	}
> +
> +	BUILD_BUG_ON(offsetof(struct pt_regs, trap) !=
> +		     offsetof(struct pt_regs, softe) + sizeof(long));
> +
> +	if (!ret)
> +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> +					  &target->thread.regs->trap,
> +					  offsetof(struct pt_regs, trap),
> +					  sizeof(struct user_pt_regs));
> +#else
>  	if (!ret)
>  		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
>  					  &target->thread.regs->orig_gpr3,
>  					  offsetof(struct pt_regs, orig_gpr3),
>  					  sizeof(struct user_pt_regs));
> +#endif
>  	if (!ret)
>  		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
>  					       sizeof(struct user_pt_regs), -1);
> -- 
> 2.5.0
>