Subject: Re: [PATCH v5 02/10] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user()

From: Daniel Axtens <[email-masked]>
Date: Fri, 05 Feb 2021 16:17:01 +1100

Hi Christopher,

I have checked that each implementation matches the corresponding
*_to_user implementation. We've had some debate about whether the
overarching implementation in the to/from pairs (especially where things
go via a bounce buffer) can be simplified - but that's probably not
really something that this patch set should do.

On that basis:
Reviewed-by: Daniel Axtens <[email-masked]>

Kind regards,
Daniel

> Reuse the "safe" implementation from signal.c except for calling
> unsafe_copy_from_user() to copy into a local buffer.
>
> Signed-off-by: Christopher M. Riedl <[email-masked]>
> ---
>  arch/powerpc/kernel/signal.h | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
>
> diff --git a/arch/powerpc/kernel/signal.h b/arch/powerpc/kernel/signal.h
> index 2559a681536e..7dfc536c78ef 100644
> --- a/arch/powerpc/kernel/signal.h
> +++ b/arch/powerpc/kernel/signal.h
> @@ -53,6 +53,30 @@ unsigned long copy_ckfpr_from_user(struct task_struct *task, void __user *from);
>  				&buf[i], label);\
>  } while (0)
>  
> +#define unsafe_copy_fpr_from_user(task, from, label)	do {		\
> +	struct task_struct *__t = task;					\
> +	u64 __user *__f = (u64 __user *)from;				\
> +	u64 buf[ELF_NFPREG];						\
> +	int i;								\
> +									\
> +	unsafe_copy_from_user(buf, __f, sizeof(buf), label);		\
> +	for (i = 0; i < ELF_NFPREG - 1; i++)				\
> +		__t->thread.TS_FPR(i) = buf[i];				\
> +	__t->thread.fp_state.fpscr = buf[i];				\
> +} while (0)
> +
> +#define unsafe_copy_vsx_from_user(task, from, label)	do {		\
> +	struct task_struct *__t = task;					\
> +	u64 __user *__f = (u64 __user *)from;				\
> +	u64 buf[ELF_NVSRHALFREG];					\
> +	int i;								\
> +									\
> +	unsafe_copy_from_user(buf, __f, sizeof(buf), label);		\
> +	for (i = 0; i < ELF_NVSRHALFREG ; i++)				\
> +		__t->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = buf[i];	\
> +} while (0)
> +
> +
>  #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
>  #define unsafe_copy_ckfpr_to_user(to, task, label)	do {		\
>  	struct task_struct *__t = task;					\
> @@ -80,6 +104,10 @@ unsigned long copy_ckfpr_from_user(struct task_struct *task, void __user *from);
>  	unsafe_copy_to_user(to, (task)->thread.fp_state.fpr,	\
>  			    ELF_NFPREG * sizeof(double), label)
>  
> +#define unsafe_copy_fpr_from_user(task, from, label)			\
> +	unsafe_copy_from_user((task)->thread.fp_state.fpr, from,	\
> +			    ELF_NFPREG * sizeof(double), label)
> +
>  static inline unsigned long
>  copy_fpr_to_user(void __user *to, struct task_struct *task)
>  {
> @@ -115,6 +143,8 @@ copy_ckfpr_from_user(struct task_struct *task, void __user *from)
>  #else
>  #define unsafe_copy_fpr_to_user(to, task, label) do { } while (0)
>  
> +#define unsafe_copy_fpr_from_user(task, from, label) do { } while (0)
> +
>  static inline unsigned long
>  copy_fpr_to_user(void __user *to, struct task_struct *task)
>  {
> -- 
> 2.26.1