diff options
author | Youling Tang <tangyouling@loongson.cn> | 2022-10-12 16:36:19 +0800 |
---|---|---|
committer | Huacai Chen <chenhuacai@loongson.cn> | 2022-10-12 16:36:19 +0800 |
commit | 4e62d1d86585e1b62b4f96ee586881dd45a443dc (patch) | |
tree | 9f2d3d290bcbca2ee14787441f1ae6d174ec1875 /arch/loongarch/kernel/crash_dump.c | |
parent | 4a03b2ac06a5bcae29371866d9d11f5bfd4c9188 (diff) |
LoongArch: Add kdump support
This patch adds support for kdump. In kdump case the normal kernel will
reserve a region for the crash kernel and jump there on panic.
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, such as kexec-tools, is responsible for allocating a
separate region for the core's ELF header within the crash kdump kernel
memory and filling it in when executing kexec_load().
Then, its location will be advertised to the crash dump kernel via a
command line argument "elfcorehdr=", and the crash dump kernel will
preserve this region for later use with arch_reserve_vmcore() at boot
time.
At the same time, the crash kdump kernel is also limited within the
"crashkernel" area via a command line argument "mem=", so as not to
destroy the original kernel dump data.
In the crash dump kernel environment, /proc/vmcore is used to access the
primary kernel's memory with copy_oldmem_page().
I tested kdump on LoongArch machines (Loongson-3A5000) and it works as
expected (suggested crashkernel parameter is "crashkernel=512M@2560M"),
you may test it by triggering a crash through /proc/sysrq-trigger:
$ sudo kexec -p /boot/vmlinux-kdump --reuse-cmdline --append="nr_cpus=1"
# echo c > /proc/sysrq-trigger
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Diffstat (limited to 'arch/loongarch/kernel/crash_dump.c')
-rw-r--r-- | arch/loongarch/kernel/crash_dump.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/crash_dump.c b/arch/loongarch/kernel/crash_dump.c new file mode 100644 index 000000000000..e559307c1092 --- /dev/null +++ b/arch/loongarch/kernel/crash_dump.c @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/crash_dump.h> +#include <linux/io.h> +#include <linux/uio.h> + +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, + size_t csize, unsigned long offset) +{ + void *vaddr; + + if (!csize) + return 0; + + vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB); + if (!vaddr) + return -ENOMEM; + + csize = copy_to_iter(vaddr + offset, csize, iter); + + memunmap(vaddr); + + return csize; +} |