1 files changed, 144 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/daifflags.h b/arch/arm64/include/asm/daifflags.h
new file mode 100644
index 0000000000..55f57dfa8e
--- /dev/null
+++ b/arch/arm64/include/asm/daifflags.h
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2017 ARM Ltd.
+ */
+#ifndef __ASM_DAIFFLAGS_H
+#define __ASM_DAIFFLAGS_H
+
+#include <linux/irqflags.h>
+
+#include <asm/arch_gicv3.h>
+#include <asm/barrier.h>
+#include <asm/cpufeature.h>
+#include <asm/ptrace.h>
+
+#define DAIF_PROCCTX		0
+#define DAIF_PROCCTX_NOIRQ	(PSR_I_BIT | PSR_F_BIT)
+#define DAIF_ERRCTX		(PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
+#define DAIF_MASK		(PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
+
+
+/* mask/save/unmask/restore all exceptions, including interrupts. */
+static inline void local_daif_mask(void)
+{
+	WARN_ON(system_has_prio_mask_debugging() &&
+		(read_sysreg_s(SYS_ICC_PMR_EL1) == (GIC_PRIO_IRQOFF |
+						    GIC_PRIO_PSR_I_SET)));
+
+	asm volatile(
+		"msr	daifset, #0xf		// local_daif_mask\n"
+		:
+		:
+		: "memory");
+
+	/* Don't really care for a dsb here, we don't intend to enable IRQs */
+	if (system_uses_irq_prio_masking())
+		gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET);
+
+	trace_hardirqs_off();
+}
+
+static inline unsigned long local_daif_save_flags(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_IRQON)
+			flags |= PSR_I_BIT | PSR_F_BIT;
+	}
+
+	return flags;
+}
+
+static inline unsigned long local_daif_save(void)
+{
+	unsigned long flags;
+
+	flags = local_daif_save_flags();
+
+	local_daif_mask();
+
+	return flags;
+}
+
+static inline void local_daif_restore(unsigned long flags)
+{
+	bool irq_disabled = flags & PSR_I_BIT;
+
+	WARN_ON(system_has_prio_mask_debugging() &&
+		(read_sysreg(daif) & (PSR_I_BIT | PSR_F_BIT)) != (PSR_I_BIT | PSR_F_BIT));
+
+	if (!irq_disabled) {
+		trace_hardirqs_on();
+
+		if (system_uses_irq_prio_masking()) {
+			gic_write_pmr(GIC_PRIO_IRQON);
+			pmr_sync();
+		}
+	} else if (system_uses_irq_prio_masking()) {
+		u64 pmr;
+
+		if (!(flags & PSR_A_BIT)) {
+			/*
+			 * If interrupts are disabled but we can take
+			 * asynchronous errors, we can take NMIs
+			 */
+			flags &= ~(PSR_I_BIT | PSR_F_BIT);
+			pmr = GIC_PRIO_IRQOFF;
+		} else {
+			pmr = GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET;
+		}
+
+		/*
+		 * 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.
+		 */
+		gic_write_pmr(pmr);
+	}
+
+	write_sysreg(flags, daif);
+
+	if (irq_disabled)
+		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;
+
+	if (interrupts_enabled(regs))
+		trace_hardirqs_on();
+
+	if (system_uses_irq_prio_masking())
+		gic_write_pmr(regs->pmr_save);
+
+	/*
+	 * 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