On system kernel, the memory region used by crash dump kernel must be specified by "crashkernel=X@Y" boot parameter. reserve_crashkernel() will allocate the region in "System RAM" and reserve it for later use.
On crash dump kernel, memory region information in system kernel is described in a specific region specified by "elfcorehdr=X@Y" boot parameter. reserve_elfcorehdr() will set aside the region to avoid data destruction by the kernel.
Crash dump kernel will access memory regions in system kernel via copy_oldmem_page(), which reads a page by ioremap'ing it assuming that such pages are not part of main memory of crash dump kernel. This is true under non-UEFI environment because kexec-tools modifies a device tree adding "usablemem" attributes to memory sections. Under UEFI, however, this is not true because UEFI remove memory sections in a device tree and export all the memory regions, even though they belong to system kernel.
So we should add "mem=X[MG]" boot parameter to limit the memory size and avoid hitting the following assertion in ioremap(): if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr)))) return NULL;
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/crash_dump.c | 71 +++++++++++++++++++++++++++++++++ arch/arm64/kernel/setup.c | 8 +++- arch/arm64/mm/init.c | 84 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 163 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/kernel/crash_dump.c
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index ac3c2e2..6fcc602 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -36,6 +36,7 @@ arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o arm64-obj-$(CONFIG_PCI) += pci.o arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o arm64-obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o +arm64-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-y += $(arm64-obj-y) vdso/ obj-m += $(arm64-obj-m) diff --git a/arch/arm64/kernel/crash_dump.c b/arch/arm64/kernel/crash_dump.c new file mode 100644 index 0000000..3d86c0a --- /dev/null +++ b/arch/arm64/kernel/crash_dump.c @@ -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 = ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE); + if (!vaddr) + return -ENOMEM; + + if (userbuf) { + if (copy_to_user(buf, vaddr + offset, csize)) { + iounmap(vaddr); + return -EFAULT; + } + } else { + memcpy(buf, vaddr + offset, csize); + } + + iounmap(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; +} diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 51ef972..7932bd0 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -31,7 +31,6 @@ #include <linux/screen_info.h> #include <linux/init.h> #include <linux/kexec.h> -#include <linux/crash_dump.h> #include <linux/root_dev.h> #include <linux/clk-provider.h> #include <linux/cpu.h> @@ -364,6 +363,12 @@ static void __init request_standard_resources(void) kernel_data.end <= res->end) request_resource(res, &kernel_data); } + +#ifdef CONFIG_KEXEC + /* User space tools will detect the region with /proc/iomem */ + if (crashk_res.end) + insert_resource(&iomem_resource, &crashk_res); +#endif }
u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID }; @@ -393,6 +398,7 @@ void __init setup_arch(char **cmdline_p) local_async_enable();
efi_init(); + arm64_memblock_init();
paging_init(); diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index ae85da6..ea70d41 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -34,6 +34,8 @@ #include <linux/dma-contiguous.h> #include <linux/efi.h> #include <linux/swiotlb.h> +#include <linux/kexec.h> +#include <linux/crash_dump.h>
#include <asm/fixmap.h> #include <asm/memory.h> @@ -66,6 +68,81 @@ static int __init early_initrd(char *p) early_param("initrd", early_initrd); #endif
+#ifdef CONFIG_KEXEC +/* + * reserve_crashkernel() - reserves memory for crash kernel + * + * This function reserves memory area given in "crashkernel=" kernel command + * line parameter. The memory reserved is used by a dump capture kernel when + * primary kernel is crashing. + */ +static void __init reserve_crashkernel(phys_addr_t limit) +{ + unsigned long long crash_size = 0, crash_base = 0; + int ret; + + ret = parse_crashkernel(boot_command_line, limit, + &crash_size, &crash_base); + if (ret) + return; + + if (crash_base == 0) { + crash_base = memblock_alloc(crash_size, 1 << 20); + if (crash_base == 0) { + pr_warn("crashkernel allocation failed (size:%llx)\n", + crash_size); + return; + } + } else { + /* User specifies base address explicitly. Sanity check */ + if (!memblock_is_region_memory(crash_base, crash_size) || + memblock_is_region_reserved(crash_base, crash_size)) { + pr_warn("crashkernel= has wrong address or size\n"); + return; + } + + if (memblock_reserve(crash_base, crash_size)) { + pr_warn("crashkernel reservation failed - out of memory\n"); + return; + } + } + + pr_info("Reserving %lldMB of memory at %lldMB for crashkernel\n", + crash_size >> 20, crash_base >> 20); + + crashk_res.start = crash_base; + crashk_res.end = crash_base + crash_size - 1; +} +#endif /* CONFIG_KEXEC */ + +#ifdef CONFIG_CRASH_DUMP +/* + * reserve_elfcorehdr() - reserves memory for elf core header + * + * This function reserves memory area given in "elfcorehdr=" kernel command + * line parameter. The memory reserved is used by a dump capture kernel to + * identify the memory used by primary kernel. + */ +static void __init reserve_elfcorehdr(void) +{ + if (!elfcorehdr_size) + return; + + if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) { + pr_warn("elfcorehdr reservation failed - memory is in use (0x%llx)\n", + elfcorehdr_addr); + return; + } + + if (memblock_reserve(elfcorehdr_addr, elfcorehdr_size)) { + pr_warn("elfcorehdr reservation failed - out of memory\n"); + return; + } + + pr_info("Reserving %lldKB of memory at %lldMB for elfcorehdr\n", + elfcorehdr_size >> 10, elfcorehdr_addr >> 20); +} +#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 @@ -170,6 +247,13 @@ void __init arm64_memblock_init(void) memblock_reserve(__virt_to_phys(initrd_start), initrd_end - initrd_start); #endif
+#ifdef CONFIG_KEXEC + reserve_crashkernel(memory_limit); +#endif +#ifdef CONFIG_CRASH_DUMP + reserve_elfcorehdr(); +#endif + early_init_fdt_scan_reserved_mem();
/* 4GB maximum for 32-bit only capable devices */