Commit 26262396 authored Sep 19, 2020 by Youling Tang Committed by Thomas Bogendoerfer Sep 21, 2020

MIPS: kexec: Add crashkernel=YM handling



When the kernel crashkernel parameter is specified with just a size,
we are supposed to allocate a region from RAM to store the crashkernel.
However, MIPS merely reserves physical address zero with no checking
that there is even RAM there.

Fix this by lifting similar code from x86, importing it to MIPS with the
MIPS specific parameters added. In the absence of any platform specific
information, we allocate the crashkernel region from the first 512MB of
physical memory (limited to CKSEG0 or KSEG0 address range).

When X is not specified, crash_base defaults to 0 (crashkernel=YM@XM).

E.g. without this patch:

The environment as follows:
[    0.000000] MIPS: machine is loongson,loongson64c-4core-ls7a
...
[    0.000000] Kernel command line: root=/dev/sda2 crashkernel=96M ...

The warning as follows:
[    0.000000] Invalid memory region reserved for crash kernel

And the iomem as follows:
00200000-0effffff : System RAM
  00200000-00b47f87 : Kernel code
  00b47f88-00dfffff : Kernel data
  00e60000-01f73c7f : Kernel bss
1a000000-1bffffff : pci@1a000000
...

With this patch:

After increasing crash_base <= 0 handling.

And the iomem as follows:
00200000-0effffff : System RAM
  00200000-00b47f87 : Kernel code
  00b47f88-00dfffff : Kernel data
  00e60000-01f73c7f : Kernel bss
  04000000-09ffffff : Crash kernel
1a000000-1bffffff : pci@1a000000
...

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

parent 5fa1f768

arch/mips/kernel/setup.c

+21 −3

Original line number	Diff line number	Diff line
		@@ -477,6 +477,11 @@ early_param("elfcorehdr", early_parse_elfcorehdr);
		#endif

		#ifdef CONFIG_KEXEC

		/* 64M alignment for crash kernel regions */
		#define CRASH_ALIGN SZ_64M
		#define CRASH_ADDR_MAX SZ_512M

		static void __init mips_parse_crashkernel(void)
		{
		unsigned long long total_mem;
		@@ -489,10 +494,23 @@ static void __init mips_parse_crashkernel(void)
		if (ret != 0 \|\| crash_size <= 0)
		return;

		if (!memblock_find_in_range(crash_base, crash_base + crash_size, crash_size, 1)) {
		if (crash_base <= 0) {
		crash_base = memblock_find_in_range(CRASH_ALIGN, CRASH_ADDR_MAX,
		crash_size, CRASH_ALIGN);
		if (!crash_base) {
		pr_warn("crashkernel reservation failed - No suitable area found.\n");
		return;
		}
		} else {
		unsigned long long start;

		start = memblock_find_in_range(crash_base, crash_base + crash_size,
		crash_size, 1);
		if (start != crash_base) {
		pr_warn("Invalid memory region reserved for crash kernel\n");
		return;
		}
		}

		crashk_res.start = crash_base;
		crashk_res.end = crash_base + crash_size - 1;

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