arch/powerpc/kernel/crash_dump.c

   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/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
  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 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  */
 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