From: takahiro.akashi@linaro.org (AKASHI Takahiro)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v35 10/14] arm64: kdump: provide /proc/vmcore file
Date: Mon, 3 Apr 2017 11:24:38 +0900 [thread overview]
Message-ID: <20170403022440.12515-8-takahiro.akashi@linaro.org> (raw)
In-Reply-To: <20170403022139.12383-1-takahiro.akashi@linaro.org>
Arch-specific functions are added to allow for implementing a crash dump
file interface, /proc/vmcore, which can be viewed as a ELF file.
A user space tool, like kexec-tools, is responsible for allocating
a separate region for the core's ELF header within crash kdump kernel
memory and filling it in when executing kexec_load().
Then, its location will be advertised to crash dump kernel via a new
device-tree property, "linux,elfcorehdr", and crash dump kernel preserves
the region for later use with reserve_elfcorehdr() at boot time.
On crash dump kernel, /proc/vmcore will access the primary kernel's memory
with copy_oldmem_page(), which feeds the data page-by-page by ioremap'ing
it since it does not reside in linear mapping on crash dump kernel.
Meanwhile, elfcorehdr_read() is simple as the region is always mapped.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: James Morse <james.morse@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/Kconfig | 11 +++++++
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/crash_dump.c | 71 ++++++++++++++++++++++++++++++++++++++++++
arch/arm64/mm/init.c | 53 +++++++++++++++++++++++++++++++
4 files changed, 136 insertions(+)
create mode 100644 arch/arm64/kernel/crash_dump.c
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3741859765cf..e7f043efff41 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -736,6 +736,17 @@ 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
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 1606c6b2a280..0fe44a7513ff 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -50,6 +50,7 @@ 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)
diff --git a/arch/arm64/kernel/crash_dump.c b/arch/arm64/kernel/crash_dump.c
new file mode 100644
index 000000000000..f46d57c31443
--- /dev/null
+++ b/arch/arm64/kernel/crash_dump.c
@@ -0,0 +1,71 @@
+/*
+ * Routines for doing kexec-based kdump
+ *
+ * Copyright (C) 2017 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((char __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;
+}
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 89ba3cd0fe44..5960bef0170d 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -39,6 +39,7 @@
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/kexec.h>
+#include <linux/crash_dump.h>
#include <asm/boot.h>
#include <asm/fixmap.h>
@@ -165,6 +166,56 @@ static void __init kexec_reserve_crashkres_pages(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 the memory occupied by an elf core header
+ * described in the device tree. 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@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
@@ -423,6 +474,8 @@ void __init arm64_memblock_init(void)
reserve_crashkernel();
+ reserve_elfcorehdr();
+
dma_contiguous_reserve(arm64_dma_phys_limit);
memblock_allow_resize();
--
2.11.1
next prev parent reply other threads:[~2017-04-03 2:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-03 2:21 [PATCH v35 00/14] arm64: add kdump support AKASHI Takahiro
2017-04-03 2:23 ` [PATCH v35 01/14] memblock: add memblock_clear_nomap() AKASHI Takahiro
2017-04-03 2:23 ` [PATCH v35 02/14] memblock: add memblock_cap_memory_range() AKASHI Takahiro
2017-04-05 17:20 ` Catalin Marinas
2017-04-03 2:24 ` [PATCH v35 03/14] arm64: limit memory regions based on DT property, usable-memory-range AKASHI Takahiro
2017-04-03 2:24 ` [PATCH v35 04/14] arm64: kdump: reserve memory for crash dump kernel AKASHI Takahiro
2017-04-03 2:24 ` [PATCH v35 05/14] arm64: mm: add set_memory_valid() AKASHI Takahiro
2017-04-03 2:24 ` [PATCH v35 06/14] arm64: kdump: protect crash dump kernel memory AKASHI Takahiro
2017-04-03 2:24 ` [PATCH v35 07/14] arm64: hibernate: preserve kdump image around hibernation AKASHI Takahiro
2017-04-03 2:24 ` [PATCH v35 08/14] arm64: kdump: implement machine_crash_shutdown() AKASHI Takahiro
2017-04-03 9:21 ` David Woodhouse
2017-04-04 7:29 ` AKASHI Takahiro
2017-04-03 2:24 ` [PATCH v35 09/14] arm64: kdump: add VMCOREINFO's for user-space tools AKASHI Takahiro
2017-04-03 2:24 ` AKASHI Takahiro [this message]
2017-04-03 2:24 ` [PATCH v35 11/14] arm64: kdump: enable kdump in defconfig AKASHI Takahiro
2017-04-03 2:24 ` [PATCH v35 12/14] Documentation: kdump: describe arm64 port AKASHI Takahiro
2017-04-03 2:26 ` [PATCH v35 13/14] Documentation: dt: chosen properties for arm64 kdump AKASHI Takahiro
2017-04-03 2:26 ` [PATCH v35 14/14] efi/libstub/arm*: Set default address and size cells values for an empty dtb AKASHI Takahiro
2017-05-22 0:25 ` [PATCH v35 00/14] arm64: add kdump support AKASHI Takahiro
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