[PATCH v15 12/20] arm64/kexec: Add core kexec support

Geoff Levand
2016-03-14T17:48:00Z

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@infradead.org>
---
arch/arm64/Kconfig | 10 +++
arch/arm64/include/asm/kexec.h | 48 +++++++++++
arch/arm64/kernel/Makefile | 2 +
arch/arm64/kernel/machine_kexec.c | 158 ++++++++++++++++++++++++++++++++++++
arch/arm64/kernel/relocate_kernel.S | 131 ++++++++++++++++++++++++++++++
include/uapi/linux/kexec.h | 1 +
6 files changed, 350 insertions(+)
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 8cc6228..3001c51 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -603,6 +603,16 @@ config PARAVIRT_TIME_ACCOUNTING

If in doubt, say N here.

+config KEXEC
+ depends on 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..04744dc
--- /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.
+ */
+
+#ifndef _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_AARCH64
+
+#ifndef __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 /* __ASSEMBLY__ */
+
+#endif
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 83cd7e6..c0aa90d 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -42,6 +42,8 @@ arm64-obj-$(CONFIG_PCI) += pci.o
arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o
arm64-obj-$(CONFIG_ACPI) += acpi.o
arm64-obj-$(CONFIG_PARAVIRT) += paravirt.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/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
new file mode 100644
index 0000000..6fd0f0c
--- /dev/null
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -0,0 +1,158 @@
+/*
+ * 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/highmem.h>
+#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 arm64_relocate_new_kernel routine. */
+extern const unsigned char arm64_relocate_new_kernel[];
+extern const unsigned long arm64_relocate_new_kernel_size;
+
+static unsigned long kimage_start;
+
+void machine_kexec_cleanup(struct kimage *kimage)
+{
+ /* 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 *kimage)
+{
+ kimage_start = kimage->start;
+ return 0;
+}
+
+/**
+ * kexec_list_flush - Helper to flush the kimage list to PoC.
+ */
+static void kexec_list_flush(struct kimage *kimage)
+{
+ kimage_entry_t *entry;
+ unsigned int flag;
+
+ for (entry = &kimage->head, flag = 0; flag != IND_DONE; entry++) {
+ void *addr = kmap(phys_to_page(*entry & PAGE_MASK));
+
+ flag = *entry & IND_FLAGS;
+
+ switch (flag) {
+ case IND_INDIRECTION:
+ entry = (kimage_entry_t *)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:
+ break;
+ default:
+ BUG();
+ }
+ kunmap(addr);
+ }
+}
+
+/**
+ * kexec_segment_flush - Helper to flush the kimage segments to PoC.
+ */
+static void kexec_segment_flush(const struct kimage *kimage)
+{
+ unsigned long i;
+
+ pr_devel("%s:\n", __func__);
+
+ for (i = 0; i < kimage->nr_segments; i++) {
+ pr_devel(" segment[%lu]: %016lx - %016lx, %lx bytes, %lu pages\n",
+ i,
+ kimage->segment[i].mem,
+ kimage->segment[i].mem + kimage->segment[i].memsz,
+ kimage->segment[i].memsz,
+ kimage->segment[i].memsz / PAGE_SIZE);
+
+ __flush_dcache_area(phys_to_virt(kimage->segment[i].mem),
+ kimage->segment[i].memsz);
+ }
+}
+
+/**
+ * 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 *kimage)
+{
+ phys_addr_t reboot_code_buffer_phys;
+ void *reboot_code_buffer;
+
+ BUG_ON(num_online_cpus() > 1);
+
+ reboot_code_buffer_phys = page_to_phys(kimage->control_code_page);
+ reboot_code_buffer = kmap(kimage->control_code_page);
+
+ /*
+ * 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);
+
+ /* Flush the reboot_code_buffer in preparation for its execution. */
+ __flush_dcache_area(reboot_code_buffer, arm64_relocate_new_kernel_size);
+ flush_icache_range((uintptr_t)reboot_code_buffer,
+ arm64_relocate_new_kernel_size);
+
+ /* Flush the kimage list. */
+ kexec_list_flush(kimage);
+
+ /* Flush the new image if already in place. */
+ if (kimage->head & IND_DONE)
+ kexec_segment_flush(kimage);
+
+ pr_info("Bye!\n");
+
+ /* Disable all DAIF exceptions. */
+ asm volatile ("msr daifset, #0xf" : : : "memory");
+
+ cpu_install_idmap();
+
+ /*
+ * cpu_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
+ * uses physical addressing to relocate the new image to its final
+ * position and transfers control to the image entry point when the
+ * relocation is complete.
+ */
+
+ cpu_soft_restart(is_hyp_mode_available(),
+ reboot_code_buffer_phys, kimage->head, kimage_start, 0);
+
+ BUG(); /* Should never get here. */
+}
+
+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..e380db3
--- /dev/null
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -0,0 +1,131 @@
+/*
+ * 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/page.h>
+#include <asm/sysreg.h>
+
+/*
+ * arm64_relocate_new_kernel - Put a 2nd stage 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. */
+ mov x18, x1 /* x18 = kimage_start */
+ mov x17, x0 /* x17 = kimage_head */
+ dcache_line_size x16, x0 /* x16 = dcache line size */
+ mov x15, xzr /* x15 = segment start */
+ mov x14, xzr /* x14 = entry ptr */
+ mov x13, xzr /* x13 = copy dest */
+
+ /* Clear the sctlr_el2 flags. */
+ mrs x0, CurrentEL
+ cmp x0, #CurrentEL_EL2
+ b.ne 1f
+ mrs x0, sctlr_el2
+ ldr x1, =SCTLR_ELx_FLAGS
+ bic x0, x0, x1
+ msr sctlr_el2, x0
+ isb
+1:
+
+ /* Check if the new image needs relocation. */
+ cbz x17, .Ldone
+ tbnz x17, IND_DONE_BIT, .Ldone
+
+.Lloop:
+ and x12, x17, PAGE_MASK /* x12 = addr */
+
+ /* Test the entry flags. */
+.Ltest_source:
+ tbz x17, IND_SOURCE_BIT, .Ltest_indirection
+
+ /* Invalidate dest page to PoC. */
+ mov x0, x13
+ add x20, x0, #PAGE_SIZE
+ sub x1, x16, #1
+ bic x0, x0, x1
+2: dc ivac, x0
+ add x0, x0, x16
+ cmp x0, x20
+ b.lo 2b
+ dsb sy
+
+ mov x20, x13
+ mov x21, x12
+ copy_page x20, x21, x0, x1, x2, x3, x4, x5, x6, x7
+
+ /* dest += PAGE_SIZE */
+ add x13, x13, PAGE_SIZE
+ b .Lnext
+
+.Ltest_indirection:
+ tbz x17, IND_INDIRECTION_BIT, .Ltest_destination
+
+ /* ptr = addr */
+ mov x14, x12
+ b .Lnext
+
+.Ltest_destination:
+ tbz x17, IND_DESTINATION_BIT, .Lnext
+
+ mov x15, x12
+
+ /* dest = addr */
+ mov x13, x12
+
+.Lnext:
+ /* entry = *ptr++ */
+ ldr x17, [x14], #8
+
+ /* while (!(entry & DONE)) */
+ tbz x17, IND_DONE_BIT, .Lloop
+
+.Ldone:
+ dsb nsh
+ ic iallu
+ dsb nsh
+ isb
+
+ /* Start new image. */
+ mov x0, xzr
+ mov x1, xzr
+ mov x2, xzr
+ mov x3, xzr
+ br x18
+
+.ltorg
+
+.align 3 /* To keep the 64-bit values below naturally aligned. */
+
+.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
diff --git a/include/uapi/linux/kexec.h b/include/uapi/linux/kexec.h
index 99048e5..aae5ebf 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_AARCH64 (183 << 16)

/* The artificial cap on the number of segments passed to kexec_load. */
#define KEXEC_SEGMENT_MAX 16
--
2.5.0