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SubjectRe: [PATCH v2 5/5] powerpc/signal: Use unsafe_copy_siginfo_to_user()
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Le 02/09/2021 à 20:38, Eric W. Biederman a écrit :
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>
>> Use unsafe_copy_siginfo_to_user() in order to do the copy
>> within the user access block.
>>
>> On an mpc 8321 (book3s/32) the improvment is about 5% on a process
>> sending a signal to itself.
>
> Nacked-by: "Eric W. Biederman" <ebiederm@xmission.com>
>
> copy_siginfo_to_user is not the same as copy_siginfo_to_user32.
>
> As in this patch breaks 32bit userspace on powerpc.

I don't understand your comment. As you can see below, copy_siginfo_to_user32() is used in the
compat case (ie 32 bit userspace on PPC64) and unsafe_copy_siginfo_to_user() is used on the
non-compat case (ie 32 bit userspace on PPC32).

So what's the issue really ?

>
>
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>> arch/powerpc/kernel/signal_32.c | 13 ++++++-------
>> arch/powerpc/kernel/signal_64.c | 5 +----
>> 2 files changed, 7 insertions(+), 11 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
>> index ff101e2b3bab..f9e16d108bc8 100644
>> --- a/arch/powerpc/kernel/signal_32.c
>> +++ b/arch/powerpc/kernel/signal_32.c
>> @@ -710,12 +710,6 @@ static long restore_tm_user_regs(struct pt_regs *regs, struct mcontext __user *s
>> }
>> #endif
>>
>> -#ifdef CONFIG_PPC64
>> -
>> -#define copy_siginfo_to_user copy_siginfo_to_user32
>> -
>> -#endif /* CONFIG_PPC64 */
>> -
>> /*
>> * Set up a signal frame for a "real-time" signal handler
>> * (one which gets siginfo).
>> @@ -779,14 +773,19 @@ int handle_rt_signal32(struct ksignal *ksig, sigset_t *oldset,
>> asm("dcbst %y0; sync; icbi %y0; sync" :: "Z" (mctx->mc_pad[0]));
>> }
>> unsafe_put_sigset_t(&frame->uc.uc_sigmask, oldset, failed);
>> +#ifndef CONFIG_COMPAT
>> + unsafe_copy_siginfo_to_user(&frame->info, &ksig->info, failed);
>> +#endif
>>
>> /* create a stack frame for the caller of the handler */
>> unsafe_put_user(regs->gpr[1], newsp, failed);
>>
>> user_access_end();
>>
>> - if (copy_siginfo_to_user(&frame->info, &ksig->info))
>> +#ifdef CONFIG_COMPAT
>> + if (copy_siginfo_to_user32(&frame->info, &ksig->info))
>> goto badframe;
>> +#endif
>>
>> regs->link = tramp;
>>
>> diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
>> index 2cca6c8febe1..82b73fbd937d 100644
>> --- a/arch/powerpc/kernel/signal_64.c
>> +++ b/arch/powerpc/kernel/signal_64.c
>> @@ -901,15 +901,12 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
>> }
>>
>> unsafe_copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set), badframe_block);
>> + unsafe_copy_siginfo_to_user(&frame->info, &ksig->info, badframe_block);
>> /* Allocate a dummy caller frame for the signal handler. */
>> unsafe_put_user(regs->gpr[1], newsp, badframe_block);
>>
>> user_write_access_end();
>>
>> - /* Save the siginfo outside of the unsafe block. */
>> - if (copy_siginfo_to_user(&frame->info, &ksig->info))
>> - goto badframe;
>> -
>> /* Make sure signal handler doesn't get spurious FP exceptions */
>> tsk->thread.fp_state.fpscr = 0;

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