@@ -683,6 +683,17 @@ config KEXEC
but it is independent of the system firmware. And like a reboot
you can start any kernel with it, not just Linux.
+config CRASH_DUMP
+ bool "Build kdump crash kernel"
+ help
+ Generate crash dump after being started by kexec. This should
+ be normally only set in special crash dump kernels which are
+ loaded in the main kernel with kexec-tools into a specially
+ reserved region and then later executed after a crash by
+ kdump/kexec.
+
+ For more details see Documentation/kdump/kdump.txt
+
config XEN_DOM0
def_bool y
depends on XEN
@@ -48,6 +48,7 @@ arm64-obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
arm64-obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o
arm64-obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o \
cpu-reset.o
+arm64-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-y += $(arm64-obj-y) vdso/ probes/
obj-m += $(arm64-obj-m)
new file mode 100644
@@ -0,0 +1,71 @@
+/*
+ * Routines for doing kexec-based kdump
+ *
+ * Copyright (C) 2014 Linaro Limited
+ * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
+ *
+ * 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/crash_dump.h>
+#include <linux/errno.h>
+#include <linux/io.h>
+#include <linux/memblock.h>
+#include <linux/uaccess.h>
+#include <asm/memory.h>
+
+/**
+ * copy_oldmem_page() - copy one page from old kernel memory
+ * @pfn: page frame number to be copied
+ * @buf: buffer where the copied page is placed
+ * @csize: number of bytes to copy
+ * @offset: offset in bytes into the page
+ * @userbuf: if set, @buf is in a user address space
+ *
+ * This function copies one page from old kernel memory into buffer pointed by
+ * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes
+ * copied or negative error in case of failure.
+ */
+ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
+ size_t csize, unsigned long offset,
+ int userbuf)
+{
+ void *vaddr;
+
+ if (!csize)
+ return 0;
+
+ vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
+ if (!vaddr)
+ return -ENOMEM;
+
+ if (userbuf) {
+ if (copy_to_user(buf, vaddr + offset, csize)) {
+ memunmap(vaddr);
+ return -EFAULT;
+ }
+ } else {
+ memcpy(buf, vaddr + offset, csize);
+ }
+
+ memunmap(vaddr);
+
+ return csize;
+}
+
+/**
+ * elfcorehdr_read - read from ELF core header
+ * @buf: buffer where the data is placed
+ * @csize: number of bytes to read
+ * @ppos: address in the memory
+ *
+ * This function reads @count bytes from elf core header which exists
+ * on crash dump kernel's memory.
+ */
+ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
+{
+ memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count);
+ return count;
+}
@@ -36,6 +36,7 @@
#include <linux/efi.h>
#include <linux/swiotlb.h>
#include <linux/kexec.h>
+#include <linux/crash_dump.h>
#include <asm/boot.h>
#include <asm/fixmap.h>
@@ -186,6 +187,57 @@ static void __init reserve_crashkernel(void)
}
#endif /* CONFIG_KEXEC_CORE */
+#ifdef CONFIG_CRASH_DUMP
+static int __init early_init_dt_scan_elfcorehdr(unsigned long node,
+ const char *uname, int depth, void *data)
+{
+ const __be32 *reg;
+ int len;
+
+ if (depth != 1 || strcmp(uname, "chosen") != 0)
+ return 0;
+
+ reg = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
+ if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
+ return 1;
+
+ elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, ®);
+ elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, ®);
+
+ return 1;
+}
+
+/*
+ * reserve_elfcorehdr() - reserves memory for elf core header
+ *
+ * This function reserves elf core header given in "elfcorehdr=" kernel
+ * command line parameter. This region contains all the information about
+ * primary kernel's core image and is used by a dump capture kernel to
+ * access the system memory on primary kernel.
+ */
+static void __init reserve_elfcorehdr(void)
+{
+ of_scan_flat_dt(early_init_dt_scan_elfcorehdr, NULL);
+
+ if (!elfcorehdr_size)
+ return;
+
+ if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
+ pr_warn("elfcorehdr is overlapped\n");
+ return;
+ }
+
+ memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
+
+ pr_info("Reserving %lldKB of memory at 0x%llx for elfcorehdr\n",
+ elfcorehdr_size >> 10, elfcorehdr_addr);
+}
+#else
+static void __init reserve_elfcorehdr(void)
+{
+ ;
+}
+#endif /* CONFIG_CRASH_DUMP */
/*
* Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It
* currently assumes that for memory starting above 4G, 32-bit devices will
@@ -444,6 +496,8 @@ void __init arm64_memblock_init(void)
reserve_crashkernel();
+ reserve_elfcorehdr();
+
dma_contiguous_reserve(arm64_dma_phys_limit);
memblock_allow_resize();
On crash dump kernel, all the information about primary kernel's system memory (core image) is available in elf core header. The primary kernel will set aside this header with reserve_elfcorehdr() at boot time and inform crash dump kernel of its location via a new device-tree property, "linux,elfcorehdr". Please note that all other architectures use traditional "elfcorehdr=" kernel parameter for this purpose. Then crash dump kernel will access the primary kernel's memory with copy_oldmem_page(), which reads one page by ioremap'ing it since it does not reside in linear mapping on crash dump kernel. We also need our own elfcorehdr_read() here since the header is placed within crash dump kernel's usable memory. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> --- arch/arm64/Kconfig | 11 +++++++ arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/crash_dump.c | 71 ++++++++++++++++++++++++++++++++++++++++++ arch/arm64/mm/init.c | 54 ++++++++++++++++++++++++++++++++ 4 files changed, 137 insertions(+) create mode 100644 arch/arm64/kernel/crash_dump.c