1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Routines for doing kexec-based kdump.
4 *
5 * Copyright (C) 2005, IBM Corp.
6 *
7 * Created by: Michael Ellerman
8 */
9
10 #undef DEBUG
11
12 #include <linux/crash_dump.h>
13 #include <linux/io.h>
14 #include <linux/memblock.h>
15 #include <linux/of.h>
16 #include <asm/code-patching.h>
17 #include <asm/kdump.h>
18 #include <asm/firmware.h>
19 #include <linux/uio.h>
20 #include <asm/rtas.h>
21 #include <asm/inst.h>
22 #include <asm/fadump.h>
23
24 #ifdef DEBUG
25 #include <asm/udbg.h>
26 #define DBG(fmt...) udbg_printf(fmt)
27 #else
28 #define DBG(fmt...)
29 #endif
30
31 #ifndef CONFIG_NONSTATIC_KERNEL
32 void __init reserve_kdump_trampoline(void)
33 {
34 memblock_reserve(0, KDUMP_RESERVE_LIMIT);
35 }
36
37 static void __init create_trampoline(unsigned long addr)
38 {
39 u32 *p = (u32 *)addr;
40
41 /* The maximum range of a single instruction branch, is the current
42 * instruction's address + (32 MB - 4) bytes. For the trampoline we
43 * need to branch to current address + 32 MB. So we insert a nop at
44 * the trampoline address, then the next instruction (+ 4 bytes)
45 * does a branch to (32 MB - 4). The net effect is that when we
46 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
47 * two instructions it doesn't require any registers.
48 */
49 patch_instruction(p, ppc_inst(PPC_RAW_NOP()));
50 patch_branch(p + 1, addr + PHYSICAL_START, 0);
51 }
52
53 void __init setup_kdump_trampoline(void)
54 {
55 unsigned long i;
56
57 DBG(" -> setup_kdump_trampoline()\n");
58
59 for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
60 create_trampoline(i);
61 }
62
63 #ifdef CONFIG_PPC_PSERIES
64 create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
65 create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
66 #endif /* CONFIG_PPC_PSERIES */
67
68 DBG(" <- setup_kdump_trampoline()\n");
69 }
70 #endif /* CONFIG_NONSTATIC_KERNEL */
71
72 ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
73 size_t csize, unsigned long offset)
74 {
75 void *vaddr;
76 phys_addr_t paddr;
77
78 if (!csize)
79 return 0;
80
81 csize = min_t(size_t, csize, PAGE_SIZE);
82 paddr = pfn << PAGE_SHIFT;
83
84 if (memblock_is_region_memory(paddr, csize)) {
85 vaddr = __va(paddr);
86 csize = copy_to_iter(vaddr + offset, csize, iter);
87 } else {
88 vaddr = ioremap_cache(paddr, PAGE_SIZE);
89 csize = copy_to_iter(vaddr + offset, csize, iter);
90 iounmap(vaddr);
91 }
92
93 return csize;
94 }
95
96 /*
97 * Return true only when kexec based kernel dump capturing method is used.
98 * This ensures all restritions applied for kdump case are not automatically
99 * applied for fadump case.
100 */
101 bool is_kdump_kernel(void)
102 {
103 return !is_fadump_active() && elfcorehdr_addr != ELFCORE_ADDR_MAX;
104 }
105 EXPORT_SYMBOL_GPL(is_kdump_kernel);
106
107 #ifdef CONFIG_PPC_RTAS
108 /*
109 * The crashkernel region will almost always overlap the RTAS region, so
110 * we have to be careful when shrinking the crashkernel region.
111 */
112 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
113 {
114 unsigned long addr;
115 const __be32 *basep, *sizep;
116 unsigned int rtas_start = 0, rtas_end = 0;
117
118 basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
119 sizep = of_get_property(rtas.dev, "rtas-size", NULL);
120
121 if (basep && sizep) {
122 rtas_start = be32_to_cpup(basep);
123 rtas_end = rtas_start + be32_to_cpup(sizep);
124 }
125
126 for (addr = begin; addr < end; addr += PAGE_SIZE) {
127 /* Does this page overlap with the RTAS region? */
128 if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
129 continue;
130
131 free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
132 }
133 }
134 #endif
135
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