summaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/machine_kexec.c
diff options
context:
space:
mode:
authorGeoff Levand <geoff@infradead.org>2016-06-23 20:54:48 +0300
committerCatalin Marinas <catalin.marinas@arm.com>2016-06-27 18:31:25 +0300
commitd28f6df1305a86715e4e7ea0f043ba01c0a0e8d9 (patch)
tree0d1f3fba97565a04c56ecf83ea24a0021d056e91 /arch/arm64/kernel/machine_kexec.c
parentf9076ecfb1216a478312b1c078d04792df6d4477 (diff)
downloadlinux-d28f6df1305a86715e4e7ea0f043ba01c0a0e8d9.tar.xz
arm64/kexec: Add core kexec support
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>
Diffstat (limited to 'arch/arm64/kernel/machine_kexec.c')
-rw-r--r--arch/arm64/kernel/machine_kexec.c170
1 files changed, 170 insertions, 0 deletions
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
new file mode 100644
index 000000000000..c40e64607545
--- /dev/null
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -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. */
+}