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Linux/arch/powerpc/kernel/crash_dump.c

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  1 /*
  2  * Routines for doing kexec-based kdump.
  3  *
  4  * Copyright (C) 2005, IBM Corp.
  5  *
  6  * Created by: Michael Ellerman
  7  *
  8  * This source code is licensed under the GNU General Public License,
  9  * Version 2.  See the file COPYING for more details.
 10  */
 11 
 12 #undef DEBUG
 13 
 14 #include <linux/crash_dump.h>
 15 #include <linux/io.h>
 16 #include <linux/memblock.h>
 17 #include <asm/code-patching.h>
 18 #include <asm/kdump.h>
 19 #include <asm/prom.h>
 20 #include <asm/firmware.h>
 21 #include <asm/uaccess.h>
 22 #include <asm/rtas.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         unsigned int *p = (unsigned int *)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_NOP);
 50         patch_branch(++p, 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 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
 73                                unsigned long offset, int userbuf)
 74 {
 75         if (userbuf) {
 76                 if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
 77                         return -EFAULT;
 78         } else
 79                 memcpy(buf, (vaddr + offset), csize);
 80 
 81         return csize;
 82 }
 83 
 84 /**
 85  * copy_oldmem_page - copy one page from "oldmem"
 86  * @pfn: page frame number to be copied
 87  * @buf: target memory address for the copy; this can be in kernel address
 88  *      space or user address space (see @userbuf)
 89  * @csize: number of bytes to copy
 90  * @offset: offset in bytes into the page (based on pfn) to begin the copy
 91  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
 92  *      otherwise @buf is in kernel address space, use memcpy().
 93  *
 94  * Copy a page from "oldmem". For this page, there is no pte mapped
 95  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
 96  */
 97 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 98                         size_t csize, unsigned long offset, int userbuf)
 99 {
100         void  *vaddr;
101         phys_addr_t paddr;
102 
103         if (!csize)
104                 return 0;
105 
106         csize = min_t(size_t, csize, PAGE_SIZE);
107         paddr = pfn << PAGE_SHIFT;
108 
109         if (memblock_is_region_memory(paddr, csize)) {
110                 vaddr = __va(paddr);
111                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
112         } else {
113                 vaddr = __ioremap(paddr, PAGE_SIZE, 0);
114                 csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
115                 iounmap(vaddr);
116         }
117 
118         return csize;
119 }
120 
121 #ifdef CONFIG_PPC_RTAS
122 /*
123  * The crashkernel region will almost always overlap the RTAS region, so
124  * we have to be careful when shrinking the crashkernel region.
125  */
126 void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
127 {
128         unsigned long addr;
129         const __be32 *basep, *sizep;
130         unsigned int rtas_start = 0, rtas_end = 0;
131 
132         basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
133         sizep = of_get_property(rtas.dev, "rtas-size", NULL);
134 
135         if (basep && sizep) {
136                 rtas_start = be32_to_cpup(basep);
137                 rtas_end = rtas_start + be32_to_cpup(sizep);
138         }
139 
140         for (addr = begin; addr < end; addr += PAGE_SIZE) {
141                 /* Does this page overlap with the RTAS region? */
142                 if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
143                         continue;
144 
145                 free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
146         }
147 }
148 #endif
149 

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