arm64/kexec: Add core kexec support
authorGeoff Levand <geoff@infradead.org>
Thu, 23 Jun 2016 17:54:48 +0000 (17:54 +0000)
committerCatalin Marinas <catalin.marinas@arm.com>
Mon, 27 Jun 2016 15:31:25 +0000 (16:31 +0100)
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>
arch/arm64/Kconfig
arch/arm64/include/asm/kexec.h [new file with mode: 0644]
arch/arm64/kernel/Makefile
arch/arm64/kernel/machine_kexec.c [new file with mode: 0644]
arch/arm64/kernel/relocate_kernel.S [new file with mode: 0644]
include/uapi/linux/kexec.h

index eb0b0a05751e98f7019caf70fe6aeb0c5f9ef0b2..1b196bf9932078bf16c702ca91608fc5a1e4beb8 100644 (file)
@@ -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
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
new file mode 100644 (file)
index 0000000..04744dc
--- /dev/null
@@ -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
index 2173149d8954c6bfe15e562f3d014fa2a00a5ba4..7700c0c2396295ac20e2a426ef2e2f8558852741 100644 (file)
@@ -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)
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
new file mode 100644 (file)
index 0000000..c40e646
--- /dev/null
@@ -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. */
+}
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
new file mode 100644 (file)
index 0000000..51b73cd
--- /dev/null
@@ -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
index 99048e501b88fb1224efb2a84e49afbcc583cffb..aae5ebf2022b30abd7cdea7b0021a707d1183e81 100644 (file)
@@ -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