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LoongArch: Add arch_crash_save_vmcoreinfo() support

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Since commit 23c85094fe ("proc/kcore: add vmcoreinfo note to /proc/
kcore") the kernel has exported the vmcoreinfo PT_NOTE on /proc/kcore
as well as /proc/vmcore.

LoongArch does not provide arch_crash_save_vmcoreinfo(), so the arch-
specific values are missing from the vmcoreinfo PT_NOTE. The generic
exporter in kernel/vmcore_info.c already provides NUMBER(VMALLOC_START),
but tools like crash cannot derive VMALLOC_END, the module and vmemmap
ranges, VA_BITS, or the KASLR offset of a LoongArch dump.

Since commit 18210a104b ("LoongArch: Expand module virtual address
space to 2GB") the vmalloc and module boundaries are no longer stable
across kernel versions either, so vmcoreinfo is the only reliable source
for them.

Provide this function in a separate file that is built at the same time
as its caller in kernel/vmcore_info.c, and add a LOONGARCH64 section to
Documentation/admin-guide/kdump/vmcoreinfo.rst.

Reported-by: Haoran Jiang <jianghaoran@kylinos.cn>
Suggested-by: Haoran Jiang <jianghaoran@kylinos.cn>
Tested-by: Tao Cui <cuitao@kylinos.cn>
Co-developed-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: George Guo <guodongtai@kylinos.cn>
Signed-off-by: Yangyang Lian <lianyangyang@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Yangyang Lian 2026-10-27 22:51:35 +08:00 committed by Huacai Chen
parent 5e0b00fd00
commit 2a5ec3a553
3 changed files with 59 additions and 0 deletions
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36
Documentation/admin-guide/kdump/vmcoreinfo.rst
View File

@ -594,3 +594,39 @@ va_kernel_pa_offset
Indicates the offset between the kernel virtual and physical mappings.
Used to translate virtual to physical addresses.
LOONGARCH64
===========
VA_BITS
-------
The maximum number of bits for virtual addresses. Used to compute the
virtual memory ranges.
PHYS_OFFSET
-----------
Indicates the physical address of the start of memory. Used to translate
virtual to physical addresses.
PAGE_OFFSET
-----------
Indicates the virtual kernel start address of the direct-mapped RAM region.
Used together with PHYS_OFFSET to translate between virtual and physical
addresses.
KERNELOFFSET
------------
The kernel randomization offset. Used to locate the kernel text in virtual
memory. If KASLR is disabled, this value is zero.
MODULES_VADDR|MODULES_END|VMALLOC_START|VMALLOC_END|VMEMMAP_START|VMEMMAP_END
-----------------------------------------------------------------------------
Used to get the correct ranges:
MODULES_VADDR ~ MODULES_END-1 : Kernel module space.
VMALLOC_START ~ VMALLOC_END-1 : vmalloc() / ioremap() space.
VMEMMAP_START ~ VMEMMAP_END-1 : vmemmap region, used for struct page array.

1
arch/loongarch/kernel/Makefile
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@ -64,6 +64,7 @@ obj-$(CONFIG_RELOCATABLE) += relocate.o
obj-$(CONFIG_KEXEC_CORE) += machine_kexec.o relocate_kernel.o
obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file.o kexec_efi.o kexec_elf.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_VMCORE_INFO) += vmcore_info.o
obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o

22
arch/loongarch/kernel/vmcore_info.c Normal file
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@ -0,0 +1,22 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/vmcore_info.h>
#include <asm/addrspace.h>
#include <asm/pgtable.h>
#include <asm/setup.h>
void arch_crash_save_vmcoreinfo(void)
{
VMCOREINFO_NUMBER(VA_BITS);
/* NUMBER(VMALLOC_START) is exported by the generic code */
vmcoreinfo_append_str("NUMBER(VMALLOC_END)=0x%lx\n", VMALLOC_END);
#ifdef CONFIG_64BIT
vmcoreinfo_append_str("NUMBER(MODULES_VADDR)=0x%lx\n", MODULES_VADDR);
vmcoreinfo_append_str("NUMBER(MODULES_END)=0x%lx\n", MODULES_END);
vmcoreinfo_append_str("NUMBER(VMEMMAP_START)=0x%lx\n", (unsigned long)vmemmap);
vmcoreinfo_append_str("NUMBER(VMEMMAP_END)=0x%lx\n", VMEMMAP_END + 1);
#endif
vmcoreinfo_append_str("NUMBER(PHYS_OFFSET)=0x%lx\n", PHYS_OFFSET);
vmcoreinfo_append_str("NUMBER(PAGE_OFFSET)=0x%lx\n", PAGE_OFFSET);
vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
}