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 
23 #ifdef DEBUG
24 #include <asm/udbg.h>
25 #define DBG(fmt...) udbg_printf(fmt)
26 #else
27 #define DBG(fmt...)
28 #endif
29 
30 #ifndef CONFIG_NONSTATIC_KERNEL
reserve_kdump_trampoline(void)31 void __init reserve_kdump_trampoline(void)
32 {
33 	memblock_reserve(0, KDUMP_RESERVE_LIMIT);
34 }
35 
create_trampoline(unsigned long addr)36 static void __init create_trampoline(unsigned long addr)
37 {
38 	u32 *p = (u32 *)addr;
39 
40 	/* The maximum range of a single instruction branch, is the current
41 	 * instruction's address + (32 MB - 4) bytes. For the trampoline we
42 	 * need to branch to current address + 32 MB. So we insert a nop at
43 	 * the trampoline address, then the next instruction (+ 4 bytes)
44 	 * does a branch to (32 MB - 4). The net effect is that when we
45 	 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
46 	 * two instructions it doesn't require any registers.
47 	 */
48 	patch_instruction(p, ppc_inst(PPC_RAW_NOP()));
49 	patch_branch(p + 1, addr + PHYSICAL_START, 0);
50 }
51 
setup_kdump_trampoline(void)52 void __init setup_kdump_trampoline(void)
53 {
54 	unsigned long i;
55 
56 	DBG(" -> setup_kdump_trampoline()\n");
57 
58 	for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
59 		create_trampoline(i);
60 	}
61 
62 #ifdef CONFIG_PPC_PSERIES
63 	create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
64 	create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
65 #endif /* CONFIG_PPC_PSERIES */
66 
67 	DBG(" <- setup_kdump_trampoline()\n");
68 }
69 #endif /* CONFIG_NONSTATIC_KERNEL */
70 
copy_oldmem_page(struct iov_iter * iter,unsigned long pfn,size_t csize,unsigned long offset)71 ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
72 			size_t csize, unsigned long offset)
73 {
74 	void  *vaddr;
75 	phys_addr_t paddr;
76 
77 	if (!csize)
78 		return 0;
79 
80 	csize = min_t(size_t, csize, PAGE_SIZE);
81 	paddr = pfn << PAGE_SHIFT;
82 
83 	if (memblock_is_region_memory(paddr, csize)) {
84 		vaddr = __va(paddr);
85 		csize = copy_to_iter(vaddr + offset, csize, iter);
86 	} else {
87 		vaddr = ioremap_cache(paddr, PAGE_SIZE);
88 		csize = copy_to_iter(vaddr + offset, csize, iter);
89 		iounmap(vaddr);
90 	}
91 
92 	return csize;
93 }
94 
95 #ifdef CONFIG_PPC_RTAS
96 /*
97  * The crashkernel region will almost always overlap the RTAS region, so
98  * we have to be careful when shrinking the crashkernel region.
99  */
crash_free_reserved_phys_range(unsigned long begin,unsigned long end)100 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
101 {
102 	unsigned long addr;
103 	const __be32 *basep, *sizep;
104 	unsigned int rtas_start = 0, rtas_end = 0;
105 
106 	basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
107 	sizep = of_get_property(rtas.dev, "rtas-size", NULL);
108 
109 	if (basep && sizep) {
110 		rtas_start = be32_to_cpup(basep);
111 		rtas_end = rtas_start + be32_to_cpup(sizep);
112 	}
113 
114 	for (addr = begin; addr < end; addr += PAGE_SIZE) {
115 		/* Does this page overlap with the RTAS region? */
116 		if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
117 			continue;
118 
119 		free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
120 	}
121 }
122 #endif
123