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ARM: 7477/1: vfp: Always save VFP state in vfp_pm_suspend on UP

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vfp_pm_suspend should save the VFP state in suspend after
any lazy context switch.  If it only saves when the VFP is enabled,
the state can get lost when, on a UP system:
  Thread 1 uses the VFP
  Context switch occurs to thread 2, VFP is disabled but the
     VFP context is not saved
  Thread 2 initiates suspend
  vfp_pm_suspend is called with the VFP disabled, and the unsaved
     VFP context of Thread 1 in the registers

Modify vfp_pm_suspend to save the VFP context whenever
vfp_current_hw_state is not NULL.

Includes a fix from Ido Yariv <ido@wizery.com>, who pointed out that on
SMP systems, the state pointer can be pointing to a freed task struct if
a task exited on another cpu, fixed by using #ifndef CONFIG_SMP in the
new if clause.

Cc: Barry Song <bs14@csr.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ido Yariv <ido@wizery.com>
Cc: Daniel Drake <dsd@laptop.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Colin Cross 2012-07-20 02:03:42 +01:00 • committed by Russell King
parent a84b895a23
commit 24b35521b8
1 changed files with 6 additions and 0 deletions
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6
arch/arm/vfp/vfpmodule.c
View file

@ -457,6 +457,12 @@ static int vfp_pm_suspend(void)
/* disable, just in case */ /* disable, just in case */
fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
} else if (vfp_current_hw_state[ti->cpu]) {
#ifndef CONFIG_SMP
fmxr(FPEXC, fpexc | FPEXC_EN);
vfp_save_state(vfp_current_hw_state[ti->cpu], fpexc);
fmxr(FPEXC, fpexc);
#endif
} }
/* clear any information we had about last context state */ /* clear any information we had about last context state */