From d066c41d10f0b2c6f8c6fb477e7d3152fdf5a8d8 Mon Sep 17 00:00:00 2001 From: James Morse Date: Fri, 26 Aug 2016 16:03:42 +0100 Subject: [PATCH] arm64: kernel: Fix unmasked debug exceptions when restoring mdscr_el1 commit 744c6c37cc18705d19e179622f927f5b781fe9cc upstream. 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 Fixes: cabe1c81ea5b ("arm64: Change cpu_resume() to enable mmu early then access sleep_sp by va") Signed-off-by: James Morse Acked-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/mm/proc.S | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 5bb61de232017..9d37e967fa198 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 -- 2.47.2