Commit 51077e03 authored Oct 25, 2019 by Mark Rutland Committed by Catalin Marinas Oct 28, 2019

arm64: add local_daif_inherit()



Some synchronous exceptions can be taken from a number of contexts,
e.g. where IRQs may or may not be masked. In the entry assembly for
these exceptions, we use the inherit_daif assembly macro to ensure
that we only mask those exceptions which were masked when the exception
was taken.

So that we can do the same from C code, this patch adds a new
local_daif_inherit() function, following the existing local_daif_*()
naming scheme.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
[moved away from local_daif_restore()]
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent e540e0a7

arch/arm64/include/asm/daifflags.h

+16 −0

Original line number	Diff line number	Diff line
		@@ -9,6 +9,7 @@

		#include <asm/arch_gicv3.h>
		#include <asm/cpufeature.h>
		#include <asm/ptrace.h>

		#define DAIF_PROCCTX 0
		#define DAIF_PROCCTX_NOIRQ PSR_I_BIT
		@@ -109,4 +110,19 @@ static inline void local_daif_restore(unsigned long flags)
		trace_hardirqs_off();
		}

		/*
		* Called by synchronous exception handlers to restore the DAIF bits that were
		* modified by taking an exception.
		*/
		static inline void local_daif_inherit(struct pt_regs *regs)
		{
		unsigned long flags = regs->pstate & DAIF_MASK;

		/*
		* We can't use local_daif_restore(regs->pstate) here as
		* system_has_prio_mask_debugging() won't restore the I bit if it can
		* use the pmr instead.
		*/
		write_sysreg(flags, daif);
		}
		#endif

Admin message