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ARM: fix PTRACE_SETVFPREGS on SMP systems

PATCH New Russell King 2 participants 2 messages May 31, 2016

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Arm (32-bit) ptrace support
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Russell King

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#0 lore raw

PATCH 1/1 ARM: fix PTRACE_SETVFPREGS on SMP systems

PTRACE_SETVFPREGS fails to properly mark the VFP register set to be reloaded, because it undoes one of the effects of vfp_flush_hwstate().

Specifically vfp_flush_hwstate() sets thread->vfpstate.hard.cpu to an invalid CPU number, but vfp_set() overwrites this with the original CPU number, thereby rendering the hardware state as apparently "valid", even though the software state is more recent.

Fix this by reverting the previous change.

Cc <[email protected]>
Fixes 8130b9d7b9d8 ("ARM: 7308/1: vfp: flush thread hwstate before copying ptrace registers")
Signed-off-by Russell King <[email protected]>

---
Will, please ack this.

 arch/arm/kernel/ptrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/arm/kernel/ptrace.c +1 -1
index ef9119f7462e..4d9375814b53 100644
@@ -733,8 +733,8 @@ static int vfp_set(struct task_struct *target,
 	if (ret)
 		return ret;
 
-	vfp_flush_hwstate(thread);
 	thread->vfpstate.hard = new_vfp;
+	vfp_flush_hwstate(thread);
 
 	return 0;
 }
Signature · 1 line
2.1.0
#1 lore raw

PATCH 1/1 ARM: fix PTRACE_SETVFPREGS on SMP systems

Quoted 8 lines · Russell King

PTRACE_SETVFPREGS fails to properly mark the VFP register set to be reloaded, because it undoes one of the effects of vfp_flush_hwstate().

Specifically vfp_flush_hwstate() sets thread->vfpstate.hard.cpu to an invalid CPU number, but vfp_set() overwrites this with the original CPU number, thereby rendering the hardware state as apparently "valid", even though the software state is more recent.

Quoted 7 lines

Fix this by reverting the previous change.

Cc <[email protected]>
Fixes 8130b9d7b9d8 ("ARM: 7308/1: vfp: flush thread hwstate before copying ptrace registers")
Signed-off-by Russell King <[email protected]>

---
Will, please ack this.

Acked-by Will Deacon <[email protected]>

Will

Quoted 27 lines
 arch/arm/kernel/ptrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/arm/kernel/ptrace.c +1 -1
index ef9119f7462e..4d9375814b53 100644
@@ -733,8 +733,8 @@ static int vfp_set(struct task_struct *target,
 	if (ret)
 		return ret;
 
-	vfp_flush_hwstate(thread);
 	thread->vfpstate.hard = new_vfp;
+	vfp_flush_hwstate(thread);
 
 	return 0;
 }
Signature · 7 lines
2.1.0


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