[PATCH 08/16] arm64/kexec: Add core kexec support

Geoff Levand geoff at infradead.org
Mon Oct 19 16:38:53 PDT 2015


Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to the
arm64 architecture that add support for the kexec re-boot mechanism
(CONFIG_KEXEC) on arm64 platforms.

Signed-off-by: Geoff Levand <geoff at infradead.org>
---
 arch/arm64/Kconfig                  |  10 +++
 arch/arm64/include/asm/kexec.h      |  48 +++++++++++
 arch/arm64/kernel/Makefile          |   2 +
 arch/arm64/kernel/cpu-reset.S       |   2 +-
 arch/arm64/kernel/machine_kexec.c   | 141 +++++++++++++++++++++++++++++++
 arch/arm64/kernel/relocate_kernel.S | 163 ++++++++++++++++++++++++++++++++++++
 include/uapi/linux/kexec.h          |   1 +
 7 files changed, 366 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/include/asm/kexec.h
 create mode 100644 arch/arm64/kernel/machine_kexec.c
 create mode 100644 arch/arm64/kernel/relocate_kernel.S

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 07d1811..73e8e31 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -491,6 +491,16 @@ config SECCOMP
 	  and the task is only allowed to execute a few safe syscalls
 	  defined by each seccomp mode.
 
+config KEXEC
+	depends on (!SMP || PM_SLEEP_SMP)
+	select KEXEC_CORE
+	bool "kexec system call"
+	---help---
+	  kexec is a system call that implements the ability to shutdown your
+	  current kernel, and to start another kernel.  It is like a reboot
+	  but it is independent of the system firmware.   And like a reboot
+	  you can start any kernel with it, not just Linux.
+
 config XEN_DOM0
 	def_bool y
 	depends on XEN
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
new file mode 100644
index 0000000..46d63cd
--- /dev/null
+++ b/arch/arm64/include/asm/kexec.h
@@ -0,0 +1,48 @@
+/*
+ * kexec for arm64
+ *
+ * Copyright (C) Linaro.
+ * Copyright (C) Huawei Futurewei Technologies.
+ *
+ * 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.
+ */
+
+#if !defined(_ARM64_KEXEC_H)
+#define _ARM64_KEXEC_H
+
+/* Maximum physical address we can use pages from */
+
+#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
+
+/* Maximum address we can reach in physical address mode */
+
+#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
+
+/* Maximum address we can use for the control code buffer */
+
+#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
+
+#define KEXEC_CONTROL_PAGE_SIZE	4096
+
+#define KEXEC_ARCH KEXEC_ARCH_ARM64
+
+#if !defined(__ASSEMBLY__)
+
+/**
+ * crash_setup_regs() - save registers for the panic kernel
+ *
+ * @newregs: registers are saved here
+ * @oldregs: registers to be saved (may be %NULL)
+ */
+
+static inline void crash_setup_regs(struct pt_regs *newregs,
+				    struct pt_regs *oldregs)
+{
+	/* Empty routine needed to avoid build errors. */
+}
+
+#endif /* !defined(__ASSEMBLY__) */
+
+#endif
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 22dc9bc..989ccd7 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -36,6 +36,8 @@ arm64-obj-$(CONFIG_EFI)			+= efi.o efi-stub.o efi-entry.o
 arm64-obj-$(CONFIG_PCI)			+= pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
 arm64-obj-$(CONFIG_ACPI)		+= acpi.o
+arm64-obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o	\
+					   cpu-reset.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)
diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index ffc9e385e..7cc7f56 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2001 Deep Blue Solutions Ltd.
  * Copyright (C) 2012 ARM Ltd.
- * Copyright (C) 2015 Huawei Futurewei Technologies.
+ * Copyright (C) Huawei Futurewei Technologies.
  *
  * 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
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
new file mode 100644
index 0000000..1fae6ae
--- /dev/null
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -0,0 +1,141 @@
+/*
+ * kexec for arm64
+ *
+ * Copyright (C) Linaro.
+ * Copyright (C) Huawei Futurewei Technologies.
+ *
+ * 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.
+ */
+
+#include <linux/kexec.h>
+#include <linux/of_fdt.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#include <asm/cacheflush.h>
+#include <asm/system_misc.h>
+
+#include "cpu-reset.h"
+
+/* Global variables for the relocate_kernel routine. */
+extern const unsigned char arm64_relocate_new_kernel[];
+extern const unsigned long arm64_relocate_new_kernel_size;
+extern unsigned long arm64_kexec_kimage_head_offset;
+extern unsigned long arm64_kexec_kimage_start_offset;
+
+static unsigned long kimage_head;
+static unsigned long kimage_start;
+
+void machine_kexec_cleanup(struct kimage *image)
+{
+	/* Empty routine needed to avoid build errors. */
+}
+
+/**
+ * machine_kexec_prepare - Prepare for a kexec reboot.
+ *
+ * Called from the core kexec code when a kernel image is loaded.
+ */
+int machine_kexec_prepare(struct kimage *image)
+{
+	kimage_start = image->start;
+	return 0;
+}
+
+/**
+ * kexec_list_flush - Helper to flush the kimage list to PoC.
+ */
+static void kexec_list_flush(unsigned long kimage_head)
+{
+	unsigned long *entry;
+
+	for (entry = &kimage_head; ; entry++) {
+		unsigned int flag = *entry & IND_FLAGS;
+		void *addr = phys_to_virt(*entry & PAGE_MASK);
+
+		switch (flag) {
+		case IND_INDIRECTION:
+			entry = (unsigned long *)addr - 1;
+			__flush_dcache_area(addr, PAGE_SIZE);
+			break;
+		case IND_DESTINATION:
+			break;
+		case IND_SOURCE:
+			__flush_dcache_area(addr, PAGE_SIZE);
+			break;
+		case IND_DONE:
+			return;
+		default:
+			BUG();
+		}
+	}
+}
+
+static void soft_restart(unsigned long addr)
+{
+	setup_mm_for_reboot();
+	cpu_soft_restart(virt_to_phys(cpu_reset), addr,
+		is_hyp_mode_available());
+
+	BUG(); /* Should never get here. */
+}
+
+/**
+ * machine_kexec - Do the kexec reboot.
+ *
+ * Called from the core kexec code for a sys_reboot with LINUX_REBOOT_CMD_KEXEC.
+ */
+void machine_kexec(struct kimage *image)
+{
+	phys_addr_t reboot_code_buffer_phys;
+	void *reboot_code_buffer;
+
+	BUG_ON(num_online_cpus() > 1);
+
+	kimage_head = image->head;
+
+	reboot_code_buffer_phys = page_to_phys(image->control_code_page);
+	reboot_code_buffer = phys_to_virt(reboot_code_buffer_phys);
+
+	/*
+	 * Copy arm64_relocate_new_kernel to the reboot_code_buffer for use
+	 * after the kernel is shut down.
+	 */
+	memcpy(reboot_code_buffer, arm64_relocate_new_kernel,
+		arm64_relocate_new_kernel_size);
+
+	/* Set the variables in reboot_code_buffer. */
+
+	memcpy(reboot_code_buffer + arm64_kexec_kimage_start_offset,
+	       &kimage_start, sizeof(kimage_start));
+	memcpy(reboot_code_buffer + arm64_kexec_kimage_head_offset,
+	       &kimage_head, sizeof(kimage_head));
+
+	/* Flush the reboot_code_buffer in preparation for its execution. */
+	__flush_dcache_area(reboot_code_buffer, arm64_relocate_new_kernel_size);
+
+	/* Flush the kimage list. */
+	kexec_list_flush(image->head);
+
+	pr_info("Bye!\n");
+
+	/* Disable all DAIF exceptions. */
+	asm volatile ("msr daifset, #0xf" : : : "memory");
+
+	/*
+	 * soft_restart() will shutdown the MMU, disable data caches, then
+	 * transfer control to the reboot_code_buffer which contains a copy of
+	 * the arm64_relocate_new_kernel routine.  arm64_relocate_new_kernel
+	 * will use physical addressing to relocate the new kernel to its final
+	 * position and then will transfer control to the entry point of the new
+	 * kernel.
+	 */
+	soft_restart(reboot_code_buffer_phys);
+}
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+	/* Empty routine needed to avoid build errors. */
+}
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
new file mode 100644
index 0000000..7b07a16
--- /dev/null
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -0,0 +1,163 @@
+/*
+ * kexec for arm64
+ *
+ * Copyright (C) Linaro.
+ * Copyright (C) Huawei Futurewei Technologies.
+ *
+ * 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.
+ */
+
+#include <linux/kexec.h>
+
+#include <asm/assembler.h>
+#include <asm/kexec.h>
+#include <asm/memory.h>
+#include <asm/page.h>
+
+
+/*
+ * arm64_relocate_new_kernel - Put a 2nd stage kernel image in place and boot it.
+ *
+ * The memory that the old kernel occupies may be overwritten when coping the
+ * new image to its final location.  To assure that the
+ * arm64_relocate_new_kernel routine which does that copy is not overwritten,
+ * all code and data needed by arm64_relocate_new_kernel must be between the
+ * symbols arm64_relocate_new_kernel and arm64_relocate_new_kernel_end.  The
+ * machine_kexec() routine will copy arm64_relocate_new_kernel to the kexec
+ * control_code_page, a special page which has been set up to be preserved
+ * during the copy operation.
+ */
+.globl arm64_relocate_new_kernel
+arm64_relocate_new_kernel:
+
+	/* Setup the list loop variables. */
+	ldr	x18, .Lkimage_head		/* x18 = list entry */
+	dcache_line_size x17, x0		/* x17 = dcache line size */
+	mov	x16, xzr			/* x16 = segment start */
+	mov	x15, xzr			/* x15 = entry ptr */
+	mov	x14, xzr			/* x14 = copy dest */
+
+	/* Check if the new image needs relocation. */
+	cbz	x18, .Ldone
+	tbnz	x18, IND_DONE_BIT, .Ldone
+
+.Lloop:
+	and	x13, x18, PAGE_MASK		/* x13 = addr */
+
+	/* Test the entry flags. */
+.Ltest_source:
+	tbz	x18, IND_SOURCE_BIT, .Ltest_indirection
+
+	mov x20, x14				/*  x20 = copy dest */
+	mov x21, x13				/*  x21 = copy src */
+
+	/* Invalidate dest page to PoC. */
+	mov	x0, x20
+	add	x19, x0, #PAGE_SIZE
+	sub	x1, x17, #1
+	bic	x0, x0, x1
+1:	dc	ivac, x0
+	add	x0, x0, x17
+	cmp	x0, x19
+	b.lo	1b
+	dsb	sy
+
+	/* Copy page. */
+1:	ldp	x22, x23, [x21]
+	ldp	x24, x25, [x21, #16]
+	ldp	x26, x27, [x21, #32]
+	ldp	x28, x29, [x21, #48]
+	add	x21, x21, #64
+	stnp	x22, x23, [x20]
+	stnp	x24, x25, [x20, #16]
+	stnp	x26, x27, [x20, #32]
+	stnp	x28, x29, [x20, #48]
+	add	x20, x20, #64
+	tst	x21, #(PAGE_SIZE - 1)
+	b.ne	1b
+
+	/* dest += PAGE_SIZE */
+	add	x14, x14, PAGE_SIZE
+	b	.Lnext
+
+.Ltest_indirection:
+	tbz	x18, IND_INDIRECTION_BIT, .Ltest_destination
+
+	/* ptr = addr */
+	mov	x15, x13
+	b	.Lnext
+
+.Ltest_destination:
+	tbz	x18, IND_DESTINATION_BIT, .Lnext
+
+	mov	x16, x13
+
+	/* dest = addr */
+	mov	x14, x13
+
+.Lnext:
+	/* entry = *ptr++ */
+	ldr	x18, [x15], #8
+
+	/* while (!(entry & DONE)) */
+	tbz	x18, IND_DONE_BIT, .Lloop
+
+.Ldone:
+	dsb	sy
+	isb
+	ic	ialluis
+	dsb	sy
+	isb
+
+	/* Start new image. */
+	ldr	x4, .Lkimage_start
+	mov	x0, xzr
+	mov	x1, xzr
+	mov	x2, xzr
+	mov	x3, xzr
+	br	x4
+
+.align 3	/* To keep the 64-bit values below naturally aligned. */
+
+/* The machine_kexec routine sets these variables via offsets from
+ * arm64_relocate_new_kernel.
+ */
+
+/*
+ * .Lkimage_start - Copy of image->start, the entry point of the new
+ * image.
+ */
+.Lkimage_start:
+	.quad	0x0
+
+/*
+ * .Lkimage_head - Copy of image->head, the list of kimage entries.
+ */
+.Lkimage_head:
+	.quad	0x0
+
+.Lcopy_end:
+.org	KEXEC_CONTROL_PAGE_SIZE
+
+/*
+ * arm64_relocate_new_kernel_size - Number of bytes to copy to the control_code_page.
+ */
+.globl arm64_relocate_new_kernel_size
+arm64_relocate_new_kernel_size:
+	.quad	.Lcopy_end - arm64_relocate_new_kernel
+
+/*
+ * arm64_kexec_kimage_start_offset - Offset for writing .Lkimage_start.
+ */
+.globl arm64_kexec_kimage_start_offset
+arm64_kexec_kimage_start_offset:
+	.quad	.Lkimage_start - arm64_relocate_new_kernel
+
+/*
+ * arm64_kexec_kimage_head_offset - Offset for writing .Lkimage_head.
+ */
+.globl arm64_kexec_kimage_head_offset
+arm64_kexec_kimage_head_offset:
+	.quad	.Lkimage_head - arm64_relocate_new_kernel
diff --git a/include/uapi/linux/kexec.h b/include/uapi/linux/kexec.h
index 99048e5..ccec467 100644
--- a/include/uapi/linux/kexec.h
+++ b/include/uapi/linux/kexec.h
@@ -39,6 +39,7 @@
 #define KEXEC_ARCH_SH      (42 << 16)
 #define KEXEC_ARCH_MIPS_LE (10 << 16)
 #define KEXEC_ARCH_MIPS    ( 8 << 16)
+#define KEXEC_ARCH_ARM64   (183 << 16)
 
 /* The artificial cap on the number of segments passed to kexec_load. */
 #define KEXEC_SEGMENT_MAX 16
-- 
2.5.0





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