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authorJames Morse <james.morse@arm.com>2016-10-18 11:27:48 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-12-08 07:15:25 +0100
commit71710cd35a554b1f0a60f035642455beeaec0f06 (patch)
tree10ec1add91c5ffdf85d12f3d4a2dae83bfdf4a25
parentd24207a0d81cee81d0f06397074db99e12cc87c1 (diff)
arm64: suspend: Reconfigure PSTATE after resume from idle
commit d08544127d9fb4505635e3cb6871fd50a42947bd upstream. The suspend/resume path in kernel/sleep.S, as used by cpu-idle, does not save/restore PSTATE. As a result of this cpufeatures that were detected and have bits in PSTATE get lost when we resume from idle. UAO gets set appropriately on the next context switch. PAN will be re-enabled next time we return from user-space, but on a preemptible kernel we may run work accessing user space before this point. Add code to re-enable theses two features in __cpu_suspend_exit(). We re-use uao_thread_switch() passing current. Signed-off-by: James Morse <james.morse@arm.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> [Removed UAO hooks and commit-message references: this feature is not present in v4.4] Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/arm64/kernel/suspend.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index 1095aa483a1c..00c1372bf57b 100644
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -1,7 +1,9 @@
#include <linux/ftrace.h>
#include <linux/percpu.h>
#include <linux/slab.h>
+#include <asm/alternative.h>
#include <asm/cacheflush.h>
+#include <asm/cpufeature.h>
#include <asm/debug-monitors.h>
#include <asm/pgtable.h>
#include <asm/memory.h>
@@ -111,6 +113,13 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
/*
+ * PSTATE was not saved over suspend/resume, re-enable any
+ * detected features that might not have been set correctly.
+ */
+ asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,
+ CONFIG_ARM64_PAN));
+
+ /*
* Restore HW breakpoint registers to sane values
* before debug exceptions are possibly reenabled
* through local_dbg_restore.