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x86: kdump: use generic interface to simplify crashkernel reservation code 

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>, and define CRASH_ALIGN,
   CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX and
   DEFAULT_CRASH_KERNEL_LOW_SIZE in <asm/crash_core.h>;

2) Add arch_reserve_crashkernel() to call parse_crashkernel() and
   reserve_crashkernel_generic(), and do the ARCH specific work if
   needed.

3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
   arch/x86/Kconfig.

When adding DEFAULT_CRASH_KERNEL_LOW_SIZE, add crash_low_size_default() to
calculate crashkernel low memory because x86_64 has special requirement.

The old reserve_crashkernel_low() and reserve_crashkernel() can be
removed.

[bhe@redhat.com: move crash_low_size_default() code into <asm/crash_core.h>]
  Link: https://lkml.kernel.org/r/ZQpeAjOmuMJBFw1/@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20230914033142.676708-7-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Jiahao <chenjiahao16@huawei.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Baoquan He 2023-09-14 11:31:39 +08:00 committed by Andrew Morton
parent b631b95dde
commit 9c08a2a139
3 changed files with 56 additions and 137 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/Kconfig
View File

@ -2062,6 +2062,9 @@ config ARCH_SUPPORTS_CRASH_DUMP
config ARCH_SUPPORTS_CRASH_HOTPLUG
def_bool y
config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
def_bool CRASH_CORE
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
default "0x1000000"

42
arch/x86/include/asm/crash_core.h Normal file
View File

@ -0,0 +1,42 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _X86_CRASH_CORE_H
#define _X86_CRASH_CORE_H
/* 16M alignment for crash kernel regions */
#define CRASH_ALIGN SZ_16M
/*
* Keep the crash kernel below this limit.
*
* Earlier 32-bits kernels would limit the kernel to the low 512 MB range
* due to mapping restrictions.
*
* 64-bit kdump kernels need to be restricted to be under 64 TB, which is
* the upper limit of system RAM in 4-level paging mode. Since the kdump
* jump could be from 5-level paging to 4-level paging, the jump will fail if
* the kernel is put above 64 TB, and during the 1st kernel bootup there's
* no good way to detect the paging mode of the target kernel which will be
* loaded for dumping.
*/
extern unsigned long swiotlb_size_or_default(void);
#ifdef CONFIG_X86_32
# define CRASH_ADDR_LOW_MAX SZ_512M
# define CRASH_ADDR_HIGH_MAX SZ_512M
#else
# define CRASH_ADDR_LOW_MAX SZ_4G
# define CRASH_ADDR_HIGH_MAX SZ_64T
#endif
# define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
static inline unsigned long crash_low_size_default(void)
{
#ifdef CONFIG_X86_64
return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
#else
return 0;
#endif
}
#endif /* _X86_CRASH_CORE_H */

148
arch/x86/kernel/setup.c
View File

@ -466,155 +466,29 @@ static void __init memblock_x86_reserve_range_setup_data(void)
}
}
/*
* --------- Crashkernel reservation ------------------------------
*/
/* 16M alignment for crash kernel regions */
#define CRASH_ALIGN SZ_16M
/*
* Keep the crash kernel below this limit.
*
* Earlier 32-bits kernels would limit the kernel to the low 512 MB range
* due to mapping restrictions.
*
* 64-bit kdump kernels need to be restricted to be under 64 TB, which is
* the upper limit of system RAM in 4-level paging mode. Since the kdump
* jump could be from 5-level paging to 4-level paging, the jump will fail if
* the kernel is put above 64 TB, and during the 1st kernel bootup there's
* no good way to detect the paging mode of the target kernel which will be
* loaded for dumping.
*/
#ifdef CONFIG_X86_32
# define CRASH_ADDR_LOW_MAX SZ_512M
# define CRASH_ADDR_HIGH_MAX SZ_512M
#else
# define CRASH_ADDR_LOW_MAX SZ_4G
# define CRASH_ADDR_HIGH_MAX SZ_64T
#endif
static int __init reserve_crashkernel_low(void)
static void __init arch_reserve_crashkernel(void)
{
#ifdef CONFIG_X86_64
unsigned long long base, low_base = 0, low_size = 0;
unsigned long low_mem_limit;
int ret;
low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
/* crashkernel=Y,low */
ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
if (ret) {
/*
* two parts from kernel/dma/swiotlb.c:
* -swiotlb size: user-specified with swiotlb= or default.
*
* -swiotlb overflow buffer: now hardcoded to 32k. We round it
* to 8M for other buffers that may need to stay low too. Also
* make sure we allocate enough extra low memory so that we
* don't run out of DMA buffers for 32-bit devices.
*/
low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
} else {
/* passed with crashkernel=0,low ? */
if (!low_size)
return 0;
}
low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
if (!low_base) {
pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
(unsigned long)(low_size >> 20));
return -ENOMEM;
}
pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (low RAM limit: %ldMB)\n",
(unsigned long)(low_size >> 20),
(unsigned long)(low_base >> 20),
(unsigned long)(low_mem_limit >> 20));
crashk_low_res.start = low_base;
crashk_low_res.end = low_base + low_size - 1;
insert_resource(&iomem_resource, &crashk_low_res);
#endif
return 0;
}
static void __init reserve_crashkernel(void)
{
unsigned long long crash_size, crash_base, total_mem;
unsigned long long crash_base, crash_size, low_size = 0;
char *cmdline = boot_command_line;
bool high = false;
int ret;
if (!IS_ENABLED(CONFIG_KEXEC_CORE))
return;
total_mem = memblock_phys_mem_size();
/* crashkernel=XM */
ret = parse_crashkernel(boot_command_line, total_mem,
&crash_size, &crash_base, NULL, NULL);
if (ret != 0 || crash_size <= 0) {
/* crashkernel=X,high */
ret = parse_crashkernel_high(boot_command_line, total_mem,
&crash_size, &crash_base);
if (ret != 0 || crash_size <= 0)
return;
high = true;
}
ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
&crash_size, &crash_base,
&low_size, &high);
if (ret)
return;
if (xen_pv_domain()) {
pr_info("Ignoring crashkernel for a Xen PV domain\n");
return;
}
/* 0 means: find the address automatically */
if (!crash_base) {
/*
* Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
* crashkernel=x,high reserves memory over 4G, also allocates
* 256M extra low memory for DMA buffers and swiotlb.
* But the extra memory is not required for all machines.
* So try low memory first and fall back to high memory
* unless "crashkernel=size[KMG],high" is specified.
*/
if (!high)
crash_base = memblock_phys_alloc_range(crash_size,
CRASH_ALIGN, CRASH_ALIGN,
CRASH_ADDR_LOW_MAX);
if (!crash_base)
crash_base = memblock_phys_alloc_range(crash_size,
CRASH_ALIGN, CRASH_ALIGN,
CRASH_ADDR_HIGH_MAX);
if (!crash_base) {
pr_info("crashkernel reservation failed - No suitable area found.\n");
return;
}
} else {
unsigned long long start;
start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
crash_base + crash_size);
if (start != crash_base) {
pr_info("crashkernel reservation failed - memory is in use.\n");
return;
}
}
if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
memblock_phys_free(crash_base, crash_size);
return;
}
pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
(unsigned long)(crash_size >> 20),
(unsigned long)(crash_base >> 20),
(unsigned long)(total_mem >> 20));
crashk_res.start = crash_base;
crashk_res.end = crash_base + crash_size - 1;
insert_resource(&iomem_resource, &crashk_res);
reserve_crashkernel_generic(cmdline, crash_size, crash_base,
low_size, high);
}
static struct resource standard_io_resources[] = {
@ -1228,7 +1102,7 @@ void __init setup_arch(char **cmdline_p)
* Reserve memory for crash kernel after SRAT is parsed so that it
* won't consume hotpluggable memory.
*/
reserve_crashkernel();
arch_reserve_crashkernel();
memblock_find_dma_reserve();