arm64: efi: Account for the EFI runtime stack in stack unwinder

The EFI runtime services run from a dedicated stack now, and so the
stack unwinder needs to be informed about this.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

Author: ardbiesheuvel

arch/arm64/include/asm/stacktrace.h

@@ -106,4 +106,19 @@ static inline struct stack_info stackinfo_get_sdei_critical(void)
 #define stackinfo_get_sdei_critical()	stackinfo_get_unknown()
 #endif
 
+#ifdef CONFIG_EFI
+extern u64 *efi_rt_stack_top;
+
+static inline struct stack_info stackinfo_get_efi(void)
+{
+	unsigned long high = (u64)efi_rt_stack_top;
+	unsigned long low = high - THREAD_SIZE;
+
+	return (struct stack_info) {
+		.low = low,
+		.high = high,
+	};
+}
+#endif
+
 #endif	/* __ASM_STACKTRACE_H */

arch/arm64/kernel/stacktrace.c

@@ -5,13 +5,15 @@
  * Copyright (C) 2012 ARM Ltd.
  */
 #include <linux/kernel.h>
+#include <linux/efi.h>
 #include <linux/export.h>
 #include <linux/ftrace.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task_stack.h>
 #include <linux/stacktrace.h>
 
+#include <asm/efi.h>
 #include <asm/irq.h>
 #include <asm/stack_pointer.h>
 #include <asm/stacktrace.h>
@@ -186,6 +188,13 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
 			: stackinfo_get_unknown();		\
 	})
 
+#define STACKINFO_EFI						\
+	({							\
+		((task == current) && current_in_efi())		\
+			? stackinfo_get_efi()			\
+			: stackinfo_get_unknown();		\
+	})
+
 noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry,
 			      void *cookie, struct task_struct *task,
 			      struct pt_regs *regs)
@@ -199,6 +208,9 @@ noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry,
 #if defined(CONFIG_VMAP_STACK) && defined(CONFIG_ARM_SDE_INTERFACE)
 		STACKINFO_SDEI(normal),
 		STACKINFO_SDEI(critical),
+#endif
+#ifdef CONFIG_EFI
+		STACKINFO_EFI,
 #endif
 	};
 	struct unwind_state state = {