From 71710cd35a554b1f0a60f035642455beeaec0f06 Mon Sep 17 00:00:00 2001 From: James Morse Date: Tue, 18 Oct 2016 11:27:48 +0100 Subject: 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 Cc: Lorenzo Pieralisi Signed-off-by: Will Deacon [Removed UAO hooks and commit-message references: this feature is not present in v4.4] Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/suspend.c | 9 +++++++++ 1 file changed, 9 insertions(+) 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 #include #include +#include #include +#include #include #include #include @@ -110,6 +112,13 @@ 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 -- cgit v1.2.3