1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _X86_CRASH_RESERVE_H
3#define _X86_CRASH_RESERVE_H
4
5/* 16M alignment for crash kernel regions */
6#define CRASH_ALIGN SZ_16M
7
8/*
9 * Keep the crash kernel below this limit.
10 *
11 * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
12 * due to mapping restrictions.
13 *
14 * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
15 * the upper limit of system RAM in 4-level paging mode. Since the kdump
16 * jump could be from 5-level paging to 4-level paging, the jump will fail if
17 * the kernel is put above 64 TB, and during the 1st kernel bootup there's
18 * no good way to detect the paging mode of the target kernel which will be
19 * loaded for dumping.
20 */
21extern unsigned long swiotlb_size_or_default(void);
22
23#ifdef CONFIG_X86_32
24# define CRASH_ADDR_LOW_MAX SZ_512M
25# define CRASH_ADDR_HIGH_MAX SZ_512M
26#else
27# define CRASH_ADDR_LOW_MAX SZ_4G
28# define CRASH_ADDR_HIGH_MAX SZ_64T
29#endif
30
31# define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
32
33static inline unsigned long crash_low_size_default(void)
34{
35#ifdef CONFIG_X86_64
36 return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
37#else
38 return 0;
39#endif
40}
41
42#define HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
43
44#endif /* _X86_CRASH_RESERVE_H */
45