[v4] powerpc: Export thread_struct.used_vr/used_vsr to user space

[Michael Ellerman]

Benjamin Herrenschmidt <benh at kernel.crashing.org> writes:

> On Thu, 2016-07-07 at 23:21 +1000, Benjamin Herrenschmidt wrote:
>> 
>> I think the right fix is that if a restore_sigcontext() has the MSR
>> bits set,
>> it should set the corresponding used_* flag.
>
> Something like this:
>
> (totally untested)

Simon/Laurent, can you guys test this and let me know if it works for
your usecase.

Cyril, can you give this a review, you've been touching this code the
most lately.

cheers

> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
> index b6aa378..1bf074e 100644
> --- a/arch/powerpc/kernel/signal_32.c
> +++ b/arch/powerpc/kernel/signal_32.c
> @@ -698,6 +698,7 @@ static long restore_user_regs(struct pt_regs *regs,
>  		if (__copy_from_user(&current->thread.vr_state, &sr->mc_vregs,
>  				     sizeof(sr->mc_vregs)))
>  			return 1;
> +		current->thread.used_vr = true;
>  	} else if (current->thread.used_vr)
>  		memset(&current->thread.vr_state, 0,
>  		       ELF_NVRREG * sizeof(vector128));
> @@ -724,6 +725,7 @@ static long restore_user_regs(struct pt_regs *regs,
>  		 */
>  		if (copy_vsx_from_user(current, &sr->mc_vsregs))
>  			return 1;
> +		current->thread.used_vsr = true;
>  	} else if (current->thread.used_vsr)
>  		for (i = 0; i < 32 ; i++)
>  			current->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
> @@ -743,6 +745,7 @@ static long restore_user_regs(struct pt_regs *regs,
>  		if (__copy_from_user(current->thread.evr, &sr->mc_vregs,
>  				     ELF_NEVRREG * sizeof(u32)))
>  			return 1;
> +		current->thread.used_spe = true;
>  	} else if (current->thread.used_spe)
>  		memset(current->thread.evr, 0, ELF_NEVRREG * sizeof(u32));
>  
> @@ -799,6 +802,7 @@ static long restore_tm_user_regs(struct pt_regs *regs,
>  				     &tm_sr->mc_vregs,
>  				     sizeof(sr->mc_vregs)))
>  			return 1;
> +		current->thread.used_vr = true;
>  	} else if (current->thread.used_vr) {
>  		memset(&current->thread.vr_state, 0,
>  		       ELF_NVRREG * sizeof(vector128));
> @@ -832,6 +836,7 @@ static long restore_tm_user_regs(struct pt_regs *regs,
>  		if (copy_vsx_from_user(current, &sr->mc_vsregs) ||
>  		    copy_transact_vsx_from_user(current, &tm_sr->mc_vsregs))
>  			return 1;
> +		current->thread.used_vsr = true;
>  	} else if (current->thread.used_vsr)
>  		for (i = 0; i < 32 ; i++) {
>  			current->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
> @@ -848,6 +853,7 @@ static long restore_tm_user_regs(struct pt_regs *regs,
>  		if (__copy_from_user(current->thread.evr, &sr->mc_vregs,
>  				     ELF_NEVRREG * sizeof(u32)))
>  			return 1;
> +		current->thread.used_spe = true;
>  	} else if (current->thread.used_spe)
>  		memset(current->thread.evr, 0, ELF_NEVRREG * sizeof(u32));
>  
> diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
> index 2552079..8704269 100644
> --- a/arch/powerpc/kernel/signal_64.c
> +++ b/arch/powerpc/kernel/signal_64.c
> @@ -363,9 +363,11 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
>  	if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
>  		return -EFAULT;
>  	/* Copy 33 vec registers (vr0..31 and vscr) from the stack */
> -	if (v_regs != NULL && (msr & MSR_VEC) != 0)
> +	if (v_regs != NULL && (msr & MSR_VEC) != 0) {
>  		err |= __copy_from_user(&current->thread.vr_state, v_regs,
>  					33 * sizeof(vector128));
> +		current->thread.used_vr = true;
> +	}
>  	else if (current->thread.used_vr)
>  		memset(&current->thread.vr_state, 0, 33 * sizeof(vector128));
>  	/* Always get VRSAVE back */
> @@ -385,9 +387,10 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
>  	 * buffer for formatting, then into the taskstruct.
>  	 */
>  	v_regs += ELF_NVRREG;
> -	if ((msr & MSR_VSX) != 0)
> +	if ((msr & MSR_VSX) != 0) {
>  		err |= copy_vsx_from_user(current, v_regs);
> -	else
> +		current->thread.used_vsr = true;
> +	} else
>  		for (i = 0; i < 32 ; i++)
>  			current->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;
>  #endif
> @@ -482,6 +485,7 @@ static long restore_tm_sigcontexts(struct pt_regs *regs,
>  					33 * sizeof(vector128));
>  		err |= __copy_from_user(&current->thread.transact_vr, tm_v_regs,
>  					33 * sizeof(vector128));
> +		current->thread.used_vr = true;
>  	}
>  	else if (current->thread.used_vr) {
>  		memset(&current->thread.vr_state, 0, 33 * sizeof(vector128));
> @@ -515,6 +519,7 @@ static long restore_tm_sigcontexts(struct pt_regs *regs,
>  		tm_v_regs += ELF_NVRREG;
>  		err |= copy_vsx_from_user(current, v_regs);
>  		err |= copy_transact_vsx_from_user(current, tm_v_regs);
> +		current->thread.used_vsr = true;
>  	} else {
>  		for (i = 0; i < 32 ; i++) {
>  			current->thread.fp_state.fpr[i][TS_VSRLOWOFFSET] = 0;