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

commit 24b35521b8ddf088531258f06f681bb7b227bf47 upstream.

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>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 61e11cea9f75809710e5f17599b7338e2f34f15f..ad83dadd151da45c352a3eba741f2d04f9fcb7d2 100644 (file)
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -453,6 +453,12 @@ static int vfp_pm_suspend(void)
 
                /* disable, just in case */
                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 */