crash_dump.c 4.0 KB

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  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. #undef DEBUG
  10. #include <linux/crash_dump.h>
  11. #include <linux/io.h>
  12. #include <linux/memblock.h>
  13. #include <asm/code-patching.h>
  14. #include <asm/kdump.h>
  15. #include <asm/prom.h>
  16. #include <asm/firmware.h>
  17. #include <linux/uaccess.h>
  18. #include <asm/rtas.h>
  19. #include <asm/inst.h>
  20. #ifdef DEBUG
  21. #include <asm/udbg.h>
  22. #define DBG(fmt...) udbg_printf(fmt)
  23. #else
  24. #define DBG(fmt...)
  25. #endif
  26. #ifndef CONFIG_NONSTATIC_KERNEL
  27. void __init reserve_kdump_trampoline(void)
  28. {
  29. memblock_reserve(0, KDUMP_RESERVE_LIMIT);
  30. }
  31. static void __init create_trampoline(unsigned long addr)
  32. {
  33. struct ppc_inst *p = (struct ppc_inst *)addr;
  34. /* The maximum range of a single instruction branch, is the current
  35. * instruction's address + (32 MB - 4) bytes. For the trampoline we
  36. * need to branch to current address + 32 MB. So we insert a nop at
  37. * the trampoline address, then the next instruction (+ 4 bytes)
  38. * does a branch to (32 MB - 4). The net effect is that when we
  39. * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
  40. * two instructions it doesn't require any registers.
  41. */
  42. patch_instruction(p, ppc_inst(PPC_INST_NOP));
  43. patch_branch((void *)p + 4, addr + PHYSICAL_START, 0);
  44. }
  45. void __init setup_kdump_trampoline(void)
  46. {
  47. unsigned long i;
  48. DBG(" -> setup_kdump_trampoline()\n");
  49. for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
  50. create_trampoline(i);
  51. }
  52. #ifdef CONFIG_PPC_PSERIES
  53. create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
  54. create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
  55. #endif /* CONFIG_PPC_PSERIES */
  56. DBG(" <- setup_kdump_trampoline()\n");
  57. }
  58. #endif /* CONFIG_NONSTATIC_KERNEL */
  59. static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
  60. unsigned long offset, int userbuf)
  61. {
  62. if (userbuf) {
  63. if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
  64. return -EFAULT;
  65. } else
  66. memcpy(buf, (vaddr + offset), csize);
  67. return csize;
  68. }
  69. /**
  70. * copy_oldmem_page - copy one page from "oldmem"
  71. * @pfn: page frame number to be copied
  72. * @buf: target memory address for the copy; this can be in kernel address
  73. * space or user address space (see @userbuf)
  74. * @csize: number of bytes to copy
  75. * @offset: offset in bytes into the page (based on pfn) to begin the copy
  76. * @userbuf: if set, @buf is in user address space, use copy_to_user(),
  77. * otherwise @buf is in kernel address space, use memcpy().
  78. *
  79. * Copy a page from "oldmem". For this page, there is no pte mapped
  80. * in the current kernel. We stitch up a pte, similar to kmap_atomic.
  81. */
  82. ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  83. size_t csize, unsigned long offset, int userbuf)
  84. {
  85. void *vaddr;
  86. phys_addr_t paddr;
  87. if (!csize)
  88. return 0;
  89. csize = min_t(size_t, csize, PAGE_SIZE);
  90. paddr = pfn << PAGE_SHIFT;
  91. if (memblock_is_region_memory(paddr, csize)) {
  92. vaddr = __va(paddr);
  93. csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
  94. } else {
  95. vaddr = ioremap_cache(paddr, PAGE_SIZE);
  96. csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
  97. iounmap(vaddr);
  98. }
  99. return csize;
  100. }
  101. #ifdef CONFIG_PPC_RTAS
  102. /*
  103. * The crashkernel region will almost always overlap the RTAS region, so
  104. * we have to be careful when shrinking the crashkernel region.
  105. */
  106. void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
  107. {
  108. unsigned long addr;
  109. const __be32 *basep, *sizep;
  110. unsigned int rtas_start = 0, rtas_end = 0;
  111. basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
  112. sizep = of_get_property(rtas.dev, "rtas-size", NULL);
  113. if (basep && sizep) {
  114. rtas_start = be32_to_cpup(basep);
  115. rtas_end = rtas_start + be32_to_cpup(sizep);
  116. }
  117. for (addr = begin; addr < end; addr += PAGE_SIZE) {
  118. /* Does this page overlap with the RTAS region? */
  119. if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
  120. continue;
  121. free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
  122. }
  123. }
  124. #endif