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

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Date:   Thu, 11 Jun 2020 14:22:30 +0530
From:   Madhavan Srinivasan <maddy@...ux.ibm.com>
To:     Oleg Nesterov <oleg@...hat.com>,
        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



On 6/10/20 8:37 PM, Oleg Nesterov wrote:
> Hi,
>
> looks like this patch was forgotten.

yep, I missed this. But mpe did have comments for the patch.

https://lkml.org/lkml/2019/9/19/107

Maddy
>
> 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
>>