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arm64/kexec: Add core kexec support

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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>
Reviewed-by: James Morse <james.morse@arm.com>
[catalin.marinas@arm.com: removed dead code following James Morse's comments]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Geoff Levand 2016-06-23 17:54:48 +00:00 committed by Catalin Marinas
parent f9076ecfb1
commit d28f6df130
6 changed files with 361 additions and 0 deletions
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10
arch/arm64/Kconfig
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@ -665,6 +665,16 @@ 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

48
arch/arm64/include/asm/kexec.h Normal file
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@ -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

2
arch/arm64/kernel/Makefile
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@ -46,6 +46,8 @@ arm64-obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL) += acpi_parking_protocol.o
arm64-obj-$(CONFIG_PARAVIRT) += paravirt.o
arm64-obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
arm64-obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.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)

170
arch/arm64/kernel/machine_kexec.c Normal file
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@ -0,0 +1,170 @@
/*
* 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/smp.h>
#include <asm/cacheflush.h>
#include <asm/cpu_ops.h>
#include <asm/mmu_context.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.
* Forbid loading a kexec kernel if we have no way of hotplugging cpus or cpus
* are stuck in the kernel. This avoids a panic once we hit machine_kexec().
*/
int machine_kexec_prepare(struct kimage *kimage)
{
kimage_start = kimage->start;
if (kimage->type != KEXEC_TYPE_CRASH && cpus_are_stuck_in_kernel()) {
pr_err("Can't kexec: CPUs are stuck in the kernel.\n");
return -EBUSY;
}
return 0;
}
/**
* kexec_list_flush - Helper to flush the kimage list and source pages to PoC.
*/
static void kexec_list_flush(struct kimage *kimage)
{
kimage_entry_t *entry;
for (entry = &kimage->head; ; entry++) {
unsigned int flag;
void *addr;
/* flush the list entries. */
__flush_dcache_area(entry, sizeof(kimage_entry_t));
flag = *entry & IND_FLAGS;
if (flag == IND_DONE)
break;
addr = phys_to_virt(*entry & PAGE_MASK);
switch (flag) {
case IND_INDIRECTION:
/* Set entry point just before the new list page. */
entry = (kimage_entry_t *)addr - 1;
break;
case IND_SOURCE:
/* flush the source pages. */
__flush_dcache_area(addr, PAGE_SIZE);
break;
case IND_DESTINATION:
break;
default:
BUG();
}
}
}
/**
* kexec_segment_flush - Helper to flush the kimage segments to PoC.
*/
static void kexec_segment_flush(const struct kimage *kimage)
{
unsigned long i;
pr_debug("%s:\n", __func__);
for (i = 0; i < kimage->nr_segments; i++) {
pr_debug(" segment[%lu]: %016lx - %016lx, 0x%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;
/*
* New cpus may have become stuck_in_kernel after we loaded the image.
*/
BUG_ON(cpus_are_stuck_in_kernel() || (num_online_cpus() > 1));
reboot_code_buffer_phys = page_to_phys(kimage->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);
/* 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 and its buffers. */
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_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(1, 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. */
}

130
arch/arm64/kernel/relocate_kernel.S Normal file
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@ -0,0 +1,130 @@
/*
* 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/linkage.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.
*/
ENTRY(arm64_relocate_new_kernel)
/* Setup the list loop variables. */
mov x17, x1 /* x17 = kimage_start */
mov x16, x0 /* x16 = kimage_head */
dcache_line_size x15, x0 /* x15 = dcache line size */
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. */
tbnz x16, IND_DONE_BIT, .Ldone
.Lloop:
and x12, x16, PAGE_MASK /* x12 = addr */
/* Test the entry flags. */
.Ltest_source:
tbz x16, IND_SOURCE_BIT, .Ltest_indirection
/* Invalidate dest page to PoC. */
mov x0, x13
add x20, x0, #PAGE_SIZE
sub x1, x15, #1
bic x0, x0, x1
2: dc ivac, x0
add x0, x0, x15
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 x16, IND_INDIRECTION_BIT, .Ltest_destination
/* ptr = addr */
mov x14, x12
b .Lnext
.Ltest_destination:
tbz x16, IND_DESTINATION_BIT, .Lnext
/* dest = addr */
mov x13, x12
.Lnext:
/* entry = *ptr++ */
ldr x16, [x14], #8
/* while (!(entry & DONE)) */
tbz x16, IND_DONE_BIT, .Lloop
.Ldone:
/* wait for writes from copy_page to finish */
dsb nsh
ic iallu
dsb nsh
isb
/* Start new image. */
mov x0, xzr
mov x1, xzr
mov x2, xzr
mov x3, xzr
br x17
ENDPROC(arm64_relocate_new_kernel)
.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

1
include/uapi/linux/kexec.h
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@ -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