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LoongArch: Use generic interface to support crashkernel=X,[high,low] 

LoongArch already supports two crashkernel regions in kexec-tools, so we
can directly use the common interface to support crashkernel=X,[high,low]
after commit 0ab97169aa ("crash_core: add generic function to do
reservation").

With the help of newly changed function parse_crashkernel() and generic
reserve_crashkernel_generic(), crashkernel reservation can be simplified
by steps:

1) Add a new header file <asm/crash_core.h>, then define CRASH_ALIGN,
   CRASH_ADDR_LOW_MAX and CRASH_ADDR_HIGH_MAX and in <asm/crash_core.h>;

2) Add arch_reserve_crashkernel() to call parse_crashkernel() and
   reserve_crashkernel_generic();

3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
   arch/loongarch/Kconfig.

One can reserve the crash kernel from high memory above DMA zone range
by explicitly passing "crashkernel=X,high"; or reserve a memory range
below 4G with "crashkernel=X,low". Besides, there are few rules need to
take notice:

1) "crashkernel=X,[high,low]" will be ignored if "crashkernel=size" is
   specified.
2) "crashkernel=X,low" is valid only when "crashkernel=X,high" is passed
   and there is enough memory to be allocated under 4G.
3) When allocating crashkernel above 4G and no "crashkernel=X,low" is
   specified, a 128M low memory will be allocated automatically for
   swiotlb bounce buffer.
See Documentation/admin-guide/kernel-parameters.txt for more information.

Following test cases have been performed as expected:
1) crashkernel=256M                          //low=256M
2) crashkernel=1G                            //low=1G
3) crashkernel=4G                            //high=4G, low=128M(default)
4) crashkernel=4G crashkernel=256M,high      //high=4G, low=128M(default), high is ignored
5) crashkernel=4G crashkernel=256M,low       //high=4G, low=128M(default), low is ignored
6) crashkernel=4G,high                       //high=4G, low=128M(default)
7) crashkernel=256M,low                      //low=0M, invalid
8) crashkernel=4G,high crashkernel=256M,low  //high=4G, low=256M
9) crashkernel=4G,high crashkernel=4G,low    //high=0M, low=0M, invalid
10) crashkernel=512M@2560M                   //low=512M
11) crashkernel=1G,high crashkernel=0M,low   //high=1G, low=0M

Recommended usage in general:
1) In the case of small memory: crashkernel=512M
2) In the case of large memory: crashkernel=1024M,high crashkernel=128M,low

Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Youling Tang 2024-01-17 12:43:08 +08:00 committed by Huacai Chen
parent c239665130
commit 78de91b458
4 changed files with 38 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
Documentation/admin-guide/kernel-parameters.txt
View File

@ -877,9 +877,9 @@
memory region [offset, offset + size] for that kernel
image. If '@offset' is omitted, then a suitable offset
is selected automatically.
[KNL, X86-64, ARM64, RISCV] Select a region under 4G first, and
fall back to reserve region above 4G when '@offset'
hasn't been specified.
[KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
under 4G first, and fall back to reserve region above
4G when '@offset' hasn't been specified.
See Documentation/admin-guide/kdump/kdump.rst for further details.
crashkernel=range1:size1[,range2:size2,...][@offset]
@ -890,25 +890,27 @@
Documentation/admin-guide/kdump/kdump.rst for an example.
crashkernel=size[KMG],high
[KNL, X86-64, ARM64, RISCV] range could be above 4G.
[KNL, X86-64, ARM64, RISCV, LoongArch] range could be
above 4G.
Allow kernel to allocate physical memory region from top,
so could be above 4G if system have more than 4G ram
installed. Otherwise memory region will be allocated
below 4G, if available.
It will be ignored if crashkernel=X is specified.
crashkernel=size[KMG],low
[KNL, X86-64, ARM64, RISCV] range under 4G. When crashkernel=X,high
is passed, kernel could allocate physical memory region
above 4G, that cause second kernel crash on system
that require some amount of low memory, e.g. swiotlb
requires at least 64M+32K low memory, also enough extra
low memory is needed to make sure DMA buffers for 32-bit
devices won't run out. Kernel would try to allocate
[KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
When crashkernel=X,high is passed, kernel could allocate
physical memory region above 4G, that cause second kernel
crash on system that require some amount of low memory,
e.g. swiotlb requires at least 64M+32K low memory, also
enough extra low memory is needed to make sure DMA buffers
for 32-bit devices won't run out. Kernel would try to allocate
default size of memory below 4G automatically. The default
size is platform dependent.
--> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
--> arm64: 128MiB
--> riscv: 128MiB
--> loongarch: 128MiB
This one lets the user specify own low range under 4G
for second kernel instead.
0: to disable low allocation.

3
arch/loongarch/Kconfig
View File

@ -594,6 +594,9 @@ config ARCH_SELECTS_CRASH_DUMP
depends on CRASH_DUMP
select RELOCATABLE
config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
def_bool CRASH_CORE
config RELOCATABLE
bool "Relocatable kernel"
help

12
arch/loongarch/include/asm/crash_core.h Normal file
View File

@ -0,0 +1,12 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef _LOONGARCH_CRASH_CORE_H
#define _LOONGARCH_CRASH_CORE_H
#define CRASH_ALIGN SZ_2M
#define CRASH_ADDR_LOW_MAX SZ_4G
#define CRASH_ADDR_HIGH_MAX memblock_end_of_DRAM()
extern phys_addr_t memblock_end_of_DRAM(void);
#endif

44
arch/loongarch/kernel/setup.c
View File

@ -252,38 +252,23 @@ static void __init arch_reserve_vmcore(void)
#endif
}
/* 2MB alignment for crash kernel regions */
#define CRASH_ALIGN SZ_2M
#define CRASH_ADDR_MAX SZ_4G
static void __init arch_parse_crashkernel(void)
static void __init arch_reserve_crashkernel(void)
{
#ifdef CONFIG_KEXEC
int ret;
unsigned long long total_mem;
unsigned long long low_size = 0;
unsigned long long crash_base, crash_size;
char *cmdline = boot_command_line;
bool high = false;
total_mem = memblock_phys_mem_size();
ret = parse_crashkernel(boot_command_line, total_mem,
&crash_size, &crash_base,
NULL, NULL);
if (ret < 0 || crash_size <= 0)
if (!IS_ENABLED(CONFIG_KEXEC_CORE))
return;
if (crash_base <= 0) {
crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, CRASH_ALIGN, CRASH_ADDR_MAX);
if (!crash_base) {
pr_warn("crashkernel reservation failed - No suitable area found.\n");
return;
}
} else if (!memblock_phys_alloc_range(crash_size, CRASH_ALIGN, crash_base, crash_base + crash_size)) {
pr_warn("Invalid memory region reserved for crash kernel\n");
ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
&crash_size, &crash_base, &low_size, &high);
if (ret)
return;
}
crashk_res.start = crash_base;
crashk_res.end = crash_base + crash_size - 1;
#endif
reserve_crashkernel_generic(cmdline, crash_size, crash_base, low_size, high);
}
static void __init fdt_setup(void)
@ -363,7 +348,7 @@ out:
void __init platform_init(void)
{
arch_reserve_vmcore();
arch_parse_crashkernel();
arch_reserve_crashkernel();
#ifdef CONFIG_ACPI_TABLE_UPGRADE
acpi_table_upgrade();
@ -473,15 +458,6 @@ static void __init resource_init(void)
request_resource(res, &data_resource);
request_resource(res, &bss_resource);
}
#ifdef CONFIG_KEXEC
if (crashk_res.start < crashk_res.end) {
insert_resource(&iomem_resource, &crashk_res);
pr_info("Reserving %ldMB of memory at %ldMB for crashkernel\n",
(unsigned long)((crashk_res.end - crashk_res.start + 1) >> 20),
(unsigned long)(crashk_res.start >> 20));
}
#endif
}
static int __init add_legacy_isa_io(struct fwnode_handle *fwnode,