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authorJames Morse <james.morse@arm.com>2016-08-26 16:03:42 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2016-09-02 17:19:55 +0100
commit744c6c37cc18705d19e179622f927f5b781fe9cc (patch)
tree60f3d8b4661573b481f76edf4a2c1f1a5efce7b1
parent63fb0a9516b2c4e23293d7253c14c40aa9c2b7d1 (diff)
arm64: kernel: Fix unmasked debug exceptions when restoring mdscr_el1
Changes to make the resume from cpu_suspend() code behave more like secondary boot caused debug exceptions to be unmasked early by __cpu_setup(). We then go on to restore mdscr_el1 in cpu_do_resume(), potentially taking break or watch points based on uninitialised registers. Mask debug exceptions in cpu_do_resume(), which is specific to resume from cpu_suspend(). Debug exceptions will be restored to their original state by local_dbg_restore() in cpu_suspend(), which runs after hw_breakpoint_restore() has re-initialised the other registers. Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Fixes: cabe1c81ea5b ("arm64: Change cpu_resume() to enable mmu early then access sleep_sp by va") Cc: <stable@vger.kernel.org> # 4.7+ Signed-off-by: James Morse <james.morse@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--arch/arm64/mm/proc.S9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 5bb61de23201..9d37e967fa19 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -100,7 +100,16 @@ ENTRY(cpu_do_resume)
msr tcr_el1, x8
msr vbar_el1, x9
+
+ /*
+ * __cpu_setup() cleared MDSCR_EL1.MDE and friends, before unmasking
+ * debug exceptions. By restoring MDSCR_EL1 here, we may take a debug
+ * exception. Mask them until local_dbg_restore() in cpu_suspend()
+ * resets them.
+ */
+ disable_dbg
msr mdscr_el1, x10
+
msr sctlr_el1, x12
/*
* Restore oslsr_el1 by writing oslar_el1