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arm64: add local_daif_inherit()

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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>
This commit is contained in:
Mark Rutland 2019-10-25 17:42:12 +01:00 committed by Catalin Marinas
parent e540e0a7fa
commit 51077e03b8
1 changed files with 16 additions and 0 deletions
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16
arch/arm64/include/asm/daifflags.h
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@ -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