1 files changed, 175 insertions, 0 deletions
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
new file mode 100644
index 000000000..0fbdf5fe6
--- /dev/null
+++ b/arch/arm64/kernel/suspend.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/pgtable.h>
+#include <linux/cpuidle.h>
+#include <asm/alternative.h>
+#include <asm/cacheflush.h>
+#include <asm/cpufeature.h>
+#include <asm/cpuidle.h>
+#include <asm/daifflags.h>
+#include <asm/debug-monitors.h>
+#include <asm/exec.h>
+#include <asm/mte.h>
+#include <asm/memory.h>
+#include <asm/mmu_context.h>
+#include <asm/smp_plat.h>
+#include <asm/suspend.h>
+
+/*
+ * This is allocated by cpu_suspend_init(), and used to store a pointer to
+ * the 'struct sleep_stack_data' the contains a particular CPUs state.
+ */
+unsigned long *sleep_save_stash;
+
+/*
+ * This hook is provided so that cpu_suspend code can restore HW
+ * breakpoints as early as possible in the resume path, before reenabling
+ * debug exceptions. Code cannot be run from a CPU PM notifier since by the
+ * time the notifier runs debug exceptions might have been enabled already,
+ * with HW breakpoints registers content still in an unknown state.
+ */
+static int (*hw_breakpoint_restore)(unsigned int);
+void __init cpu_suspend_set_dbg_restorer(int (*hw_bp_restore)(unsigned int))
+{
+	/* Prevent multiple restore hook initializations */
+	if (WARN_ON(hw_breakpoint_restore))
+		return;
+	hw_breakpoint_restore = hw_bp_restore;
+}
+
+void notrace __cpu_suspend_exit(void)
+{
+	unsigned int cpu = smp_processor_id();
+
+	mte_suspend_exit();
+
+	/*
+	 * We are resuming from reset with the idmap active in TTBR0_EL1.
+	 * We must uninstall the idmap and restore the expected MMU
+	 * state before we can possibly return to userspace.
+	 */
+	cpu_uninstall_idmap();
+
+	/* Restore CnP bit in TTBR1_EL1 */
+	if (system_supports_cnp())
+		cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir);
+
+	/*
+	 * PSTATE was not saved over suspend/resume, re-enable any detected
+	 * features that might not have been set correctly.
+	 */
+	if (cpus_have_const_cap(ARM64_HAS_DIT))
+		set_pstate_dit(1);
+	__uaccess_enable_hw_pan();
+
+	/*
+	 * Restore HW breakpoint registers to sane values
+	 * before debug exceptions are possibly reenabled
+	 * by cpu_suspend()s local_daif_restore() call.
+	 */
+	if (hw_breakpoint_restore)
+		hw_breakpoint_restore(cpu);
+
+	/*
+	 * On resume, firmware implementing dynamic mitigation will
+	 * have turned the mitigation on. If the user has forcefully
+	 * disabled it, make sure their wishes are obeyed.
+	 */
+	spectre_v4_enable_mitigation(NULL);
+
+	/* Restore additional feature-specific configuration */
+	ptrauth_suspend_exit();
+}
+
+/*
+ * cpu_suspend
+ *
+ * arg: argument to pass to the finisher function
+ * fn: finisher function pointer
+ *
+ */
+int cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
+{
+	int ret = 0;
+	unsigned long flags;
+	struct sleep_stack_data state;
+	struct arm_cpuidle_irq_context context;
+
+	/* Report any MTE async fault before going to suspend */
+	mte_suspend_enter();
+
+	/*
+	 * From this point debug exceptions are disabled to prevent
+	 * updates to mdscr register (saved and restored along with
+	 * general purpose registers) from kernel debuggers.
+	 *
+	 * Strictly speaking the trace_hardirqs_off() here is superfluous,
+	 * hardirqs should be firmly off by now. This really ought to use
+	 * something like raw_local_daif_save().
+	 */
+	flags = local_daif_save();
+
+	/*
+	 * Function graph tracer state gets inconsistent when the kernel
+	 * calls functions that never return (aka suspend finishers) hence
+	 * disable graph tracing during their execution.
+	 */
+	pause_graph_tracing();
+
+	/*
+	 * Switch to using DAIF.IF instead of PMR in order to reliably
+	 * resume if we're using pseudo-NMIs.
+	 */
+	arm_cpuidle_save_irq_context(&context);
+
+	ct_cpuidle_enter();
+
+	if (__cpu_suspend_enter(&state)) {
+		/* Call the suspend finisher */
+		ret = fn(arg);
+
+		/*
+		 * Never gets here, unless the suspend finisher fails.
+		 * Successful cpu_suspend() should return from cpu_resume(),
+		 * returning through this code path is considered an error
+		 * If the return value is set to 0 force ret = -EOPNOTSUPP
+		 * to make sure a proper error condition is propagated
+		 */
+		if (!ret)
+			ret = -EOPNOTSUPP;
+
+		ct_cpuidle_exit();
+	} else {
+		ct_cpuidle_exit();
+		__cpu_suspend_exit();
+	}
+
+	arm_cpuidle_restore_irq_context(&context);
+
+	unpause_graph_tracing();
+
+	/*
+	 * Restore pstate flags. OS lock and mdscr have been already
+	 * restored, so from this point onwards, debugging is fully
+	 * reenabled if it was enabled when core started shutdown.
+	 */
+	local_daif_restore(flags);
+
+	return ret;
+}
+
+static int __init cpu_suspend_init(void)
+{
+	/* ctx_ptr is an array of physical addresses */
+	sleep_save_stash = kcalloc(mpidr_hash_size(), sizeof(*sleep_save_stash),
+				   GFP_KERNEL);
+
+	if (WARN_ON(!sleep_save_stash))
+		return -ENOMEM;
+
+	return 0;
+}
+early_initcall(cpu_suspend_init);