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/*
* Copyright (C) 2017 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __ASM_DAIFFLAGS_H
#define __ASM_DAIFFLAGS_H
#include <linux/irqflags.h>
#include <asm/cpufeature.h>
#define DAIF_PROCCTX 0
#define DAIF_PROCCTX_NOIRQ PSR_I_BIT
#define DAIF_ERRCTX (PSR_I_BIT | PSR_A_BIT)
/* mask/save/unmask/restore all exceptions, including interrupts. */
static inline void local_daif_mask(void)
{
asm volatile(
"msr daifset, #0xf // local_daif_mask\n"
:
:
: "memory");
trace_hardirqs_off();
}
static inline unsigned long local_daif_save(void)
{
unsigned long 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();
return flags;
}
static inline void local_daif_restore(unsigned long flags)
{
bool irq_disabled = flags & PSR_I_BIT;
if (!irq_disabled) {
trace_hardirqs_on();
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();
}
}
write_sysreg(flags, daif);
if (irq_disabled)
trace_hardirqs_off();
}
#endif
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