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 <asm/code-patching.h> 16 #include <asm/kdump.h> 17 #include <asm/prom.h> 18 #include <asm/firmware.h> 19 #include <linux/uaccess.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 31 void __init reserve_kdump_trampoline(void) 32 { 33 memblock_reserve(0, KDUMP_RESERVE_LIMIT); 34 } 35 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 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 71 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize, 72 unsigned long offset, int userbuf) 73 { 74 if (userbuf) { 75 if (copy_to_user((char __user *)buf, (vaddr + offset), csize)) 76 return -EFAULT; 77 } else 78 memcpy(buf, (vaddr + offset), csize); 79 80 return csize; 81 } 82 83 /** 84 * copy_oldmem_page - copy one page from "oldmem" 85 * @pfn: page frame number to be copied 86 * @buf: target memory address for the copy; this can be in kernel address 87 * space or user address space (see @userbuf) 88 * @csize: number of bytes to copy 89 * @offset: offset in bytes into the page (based on pfn) to begin the copy 90 * @userbuf: if set, @buf is in user address space, use copy_to_user(), 91 * otherwise @buf is in kernel address space, use memcpy(). 92 * 93 * Copy a page from "oldmem". For this page, there is no pte mapped 94 * in the current kernel. We stitch up a pte, similar to kmap_atomic. 95 */ 96 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, 97 size_t csize, unsigned long offset, int userbuf) 98 { 99 void *vaddr; 100 phys_addr_t paddr; 101 102 if (!csize) 103 return 0; 104 105 csize = min_t(size_t, csize, PAGE_SIZE); 106 paddr = pfn << PAGE_SHIFT; 107 108 if (memblock_is_region_memory(paddr, csize)) { 109 vaddr = __va(paddr); 110 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); 111 } else { 112 vaddr = ioremap_cache(paddr, PAGE_SIZE); 113 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf); 114 iounmap(vaddr); 115 } 116 117 return csize; 118 } 119 120 #ifdef CONFIG_PPC_RTAS 121 /* 122 * The crashkernel region will almost always overlap the RTAS region, so 123 * we have to be careful when shrinking the crashkernel region. 124 */ 125 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end) 126 { 127 unsigned long addr; 128 const __be32 *basep, *sizep; 129 unsigned int rtas_start = 0, rtas_end = 0; 130 131 basep = of_get_property(rtas.dev, "linux,rtas-base", NULL); 132 sizep = of_get_property(rtas.dev, "rtas-size", NULL); 133 134 if (basep && sizep) { 135 rtas_start = be32_to_cpup(basep); 136 rtas_end = rtas_start + be32_to_cpup(sizep); 137 } 138 139 for (addr = begin; addr < end; addr += PAGE_SIZE) { 140 /* Does this page overlap with the RTAS region? */ 141 if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start)) 142 continue; 143 144 free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT)); 145 } 146 } 147 #endif 148