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