Re: powerpc: set used_vsr/used_vr/used_spe in sigreturn path when MSR bits are active

[Michael Ellerman]

On Tue, 2016-26-07 at 08:06:01 UTC, Simon Guo wrote:
> From: Simon Guo 
> 
> Normally, when MSR[VSX/VR/SPE] bits = 1, the used_vsr/used_vr/used_spe
> bit have already been set. However signal frame locates at user space
> and it is controlled by user application. It is up to kernel to make
> sure used_vsr/used_vr/used_spe(in kernel)=1 and consistent with MSR
> bits.
> 
> For example, CRIU application, who utilizes sigreturn to restore
> checkpointed process, will lead to the case where MSR[VSX] bit is
> active in signal frame, but used_vsx bit is not set. (the same applies
> to VR/SPE).
> 
> This patch will reinforce this at kernel by always setting used_* bit
> when MSR related bits are active in signal frame and we are doing
> sigreturn.
> 
> This patch is based on Ben's Proposal.
> 
> Signed-off-by: Benjamin Herrenschmidt 
> Signed-off-by: Simon Guo 

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/e1c0d66fcb179a1737b3d5cc11

cheers

Re: [PATCH] powerpc: set used_vsr/used_vr/used_spe in sigreturn path when MSR bits are active

[Simon Guo]

On Tue, Jul 26, 2016 at 04:06:01PM +0800, wei.guo.si...@gmail.com wrote:
> From: Simon Guo 
> 
> Normally, when MSR[VSX/VR/SPE] bits = 1, the used_vsr/used_vr/used_spe
> bit have already been set. However signal frame locates at user space
> and it is controlled by user application. It is up to kernel to make
> sure used_vsr/used_vr/used_spe(in kernel)=1 and consistent with MSR
> bits.
> 
> For example, CRIU application, who utilizes sigreturn to restore
> checkpointed process, will lead to the case where MSR[VSX] bit is
> active in signal frame, but used_vsx bit is not set. (the same applies
> to VR/SPE).
> 
> This patch will reinforce this at kernel by always setting used_* bit
> when MSR related bits are active in signal frame and we are doing
> sigreturn.
> 
> This patch is based on Ben's Proposal.
> 
Hi Michael,

Just a ping for this patch. 
The history locates at:
http://linuxppc.10917.n7.nabble.com/PATCH-v4-powerpc-Export-thread-struct-used-vr-used-vsr-to-user-space-td110147.html#a110161

If any addtional work required, please let me know.

Thanks,
- Simon

[PATCH] powerpc: set used_vsr/used_vr/used_spe in sigreturn path when MSR bits are active

[wei . guo . simon]

From: Simon Guo 

Normally, when MSR[VSX/VR/SPE] bits = 1, the used_vsr/used_vr/used_spe
bit have already been set. However signal frame locates at user space
and it is controlled by user application. It is up to kernel to make
sure used_vsr/used_vr/used_spe(in kernel)=1 and consistent with MSR
bits.

For example, CRIU application, who utilizes sigreturn to restore
checkpointed process, will lead to the case where MSR[VSX] bit is
active in signal frame, but used_vsx bit is not set. (the same applies
to VR/SPE).

This patch will reinforce this at kernel by always setting used_* bit
when MSR related bits are active in signal frame and we are doing
sigreturn.

This patch is based on Ben's Proposal.

Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Anton Blanchard 
Cc: Cyril Bur 
Cc: Michael Neuling 
Cc: Andrew Morton 
Cc: "Amanieu d'Antras" 
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Simon Guo 
---
 arch/powerpc/kernel/signal_32.c |  6 ++
 arch/powerpc/kernel/signal_64.c | 11 ---
 2 files changed, 14 insertions(+), 3 deletions(-)

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(>thread.vr_state, >mc_vregs,
 sizeof(sr->mc_vregs)))
return 1;
+   current->thread.used_vr = true;
} else if (current->thread.used_vr)
memset(>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, >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, >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,
 _sr->mc_vregs,
 sizeof(sr->mc_vregs)))
return 1;
+   current->thread.used_vr = true;
} else if (current->thread.used_vr) {
memset(>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, >mc_vsregs) ||
copy_transact_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;
@@ -848,6 +853,7 @@ static long restore_tm_user_regs(struct pt_regs *regs,
if (__copy_from_user(current->thread.evr, >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(>thread.vr_state, v_regs,
33 * sizeof(vector128));
+   current->thread.used_vr = true;
+   }
else if (current->thread.used_vr)
memset(>thread.vr_state, 0, 33 * sizeof(vector128));
/* Always get VRSAVE back */
@@ -385,9 +387,10 @@ static