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author | 2021-04-19 03:55:39 +0300 | |
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committer | 2021-04-26 08:25:24 -0700 | |
commit | 5640975003d0234da08559677e22ec25b9cb3267 (patch) | |
tree | a6707467c591146b277e5d846ef5d8fbe9d01bea /arch/riscv/kernel/crash_dump.c | |
parent | RISC-V: Add kdump support (diff) | |
download | linux-5640975003d0234da08559677e22ec25b9cb3267.tar.gz linux-5640975003d0234da08559677e22ec25b9cb3267.tar.bz2 linux-5640975003d0234da08559677e22ec25b9cb3267.zip |
RISC-V: Add crash kernel support
This patch allows Linux to act as a crash kernel for use with
kdump. Userspace will let the crash kernel know about the
memory region it can use through linux,usable-memory property
on the /memory node (overriding its reg property), and about the
memory region where the elf core header of the previous kernel
is saved, through a reserved-memory node with a compatible string
of "linux,elfcorehdr". This approach is the least invasive and
re-uses functionality already present.
I tested this on riscv64 qemu and it works as expected, you
may test it by retrieving the dmesg of the previous kernel
through /proc/vmcore, using the vmcore-dmesg utility from
kexec-tools.
Signed-off-by: Nick Kossifidis <mick@ics.forth.gr>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv/kernel/crash_dump.c')
-rw-r--r-- | arch/riscv/kernel/crash_dump.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/arch/riscv/kernel/crash_dump.c b/arch/riscv/kernel/crash_dump.c new file mode 100644 index 000000000000..86cc0ada5752 --- /dev/null +++ b/arch/riscv/kernel/crash_dump.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This code comes from arch/arm64/kernel/crash_dump.c + * Created by: AKASHI Takahiro <takahiro.akashi@linaro.org> + * Copyright (C) 2017 Linaro Limited + */ + +#include <linux/crash_dump.h> +#include <linux/io.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; +} |