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arm64: daifflags: Include PMR in daifflags restore operations

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The addition of PMR should not bypass the semantics of daifflags.

When DA_F are set, I bit is also set as no interrupts (even of higher
priority) is allowed.

When DA_F are cleared, I bit is cleared and interrupt enabling/disabling
goes through ICC_PMR_EL1.

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Julien Thierry 2019-01-31 14:58:51 +00:00 committed by Catalin Marinas
parent 4a503217ce
commit 8cb7eff32c
1 changed files with 46 additions and 4 deletions
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50
arch/arm64/include/asm/daifflags.h
View File

@ -18,6 +18,8 @@
#include <linux/irqflags.h>
#include <asm/cpufeature.h>
#define DAIF_PROCCTX 0
#define DAIF_PROCCTX_NOIRQ PSR_I_BIT
@ -36,7 +38,13 @@ static inline unsigned long local_daif_save(void)
{
unsigned long flags;
flags = arch_local_save_flags();
flags = read_sysreg(daif);
if (system_uses_irq_prio_masking()) {
/* If IRQs are masked with PMR, reflect it in the flags */
if (read_sysreg_s(SYS_ICC_PMR_EL1) <= GIC_PRIO_IRQOFF)
flags |= PSR_I_BIT;
}
local_daif_mask();
@ -45,12 +53,46 @@ static inline unsigned long local_daif_save(void)
static inline void local_daif_restore(unsigned long flags)
{
if (!arch_irqs_disabled_flags(flags))
bool irq_disabled = flags & PSR_I_BIT;
if (!irq_disabled) {
trace_hardirqs_on();
arch_local_irq_restore(flags);
if (system_uses_irq_prio_masking())
arch_local_irq_enable();
} else if (!(flags & PSR_A_BIT)) {
/*
* If interrupts are disabled but we can take
* asynchronous errors, we can take NMIs
*/
if (system_uses_irq_prio_masking()) {
flags &= ~PSR_I_BIT;
/*
* There has been concern that the write to daif
* might be reordered before this write to PMR.
* From the ARM ARM DDI 0487D.a, section D1.7.1
* "Accessing PSTATE fields":
* Writes to the PSTATE fields have side-effects on
* various aspects of the PE operation. All of these
* side-effects are guaranteed:
* - Not to be visible to earlier instructions in
* the execution stream.
* - To be visible to later instructions in the
* execution stream
*
* Also, writes to PMR are self-synchronizing, so no
* interrupts with a lower priority than PMR is signaled
* to the PE after the write.
*
* So we don't need additional synchronization here.
*/
arch_local_irq_disable();
}
}
if (arch_irqs_disabled_flags(flags))
write_sysreg(flags, daif);
if (irq_disabled)
trace_hardirqs_off();
}