/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/uaccess.h>
 20#include <asm/rtas.h>
 21
 22#ifdef DEBUG
 23#include <asm/udbg.h>
 24#define DBG(fmt...) udbg_printf(fmt)
 25#else
 26#define DBG(fmt...)
 27#endif
 28
 29#ifndef CONFIG_NONSTATIC_KERNEL
 30void __init reserve_kdump_trampoline(void)
 31{
 32	memblock_reserve(0, KDUMP_RESERVE_LIMIT);
 33}
 34
 35static void __init create_trampoline(unsigned long addr)
 36{
 37	unsigned int *p = (unsigned int *)addr;
 38
 39	/* The maximum range of a single instruction branch, is the current
 40	 * instruction's address + (32 MB - 4) bytes. For the trampoline we
 41	 * need to branch to current address + 32 MB. So we insert a nop at
 42	 * the trampoline address, then the next instruction (+ 4 bytes)
 43	 * does a branch to (32 MB - 4). The net effect is that when we
 44	 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
 45	 * two instructions it doesn't require any registers.
 46	 */
 47	patch_instruction(p, PPC_INST_NOP);
 48	patch_branch(++p, addr + PHYSICAL_START, 0);
 49}
 50
 51void __init setup_kdump_trampoline(void)
 52{
 53	unsigned long i;
 54
 55	DBG(" -> setup_kdump_trampoline()\n");
 56
 57	for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
 58		create_trampoline(i);
 59	}
 60
 61#ifdef CONFIG_PPC_PSERIES
 62	create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
 63	create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);
 64#endif /* CONFIG_PPC_PSERIES */
 65
 66	DBG(" <- setup_kdump_trampoline()\n");
 67}
 68#endif /* CONFIG_NONSTATIC_KERNEL */
 69
 70static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
 71                               unsigned long offset, int userbuf)
 72{
 73	if (userbuf) {
 74		if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
 75			return -EFAULT;
 76	} else
 77		memcpy(buf, (vaddr + offset), csize);
 78
 79	return csize;
 80}
 81
 82/**
 83 * copy_oldmem_page - copy one page from "oldmem"
 84 * @pfn: page frame number to be copied
 85 * @buf: target memory address for the copy; this can be in kernel address
 86 *      space or user address space (see @userbuf)
 87 * @csize: number of bytes to copy
 88 * @offset: offset in bytes into the page (based on pfn) to begin the copy
 89 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
 90 *      otherwise @buf is in kernel address space, use memcpy().
 91 *
 92 * Copy a page from "oldmem". For this page, there is no pte mapped
 93 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
 94 */
 95ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
 96			size_t csize, unsigned long offset, int userbuf)
 97{
 98	void  *vaddr;
 99	phys_addr_t paddr;
100
101	if (!csize)
102		return 0;
103
104	csize = min_t(size_t, csize, PAGE_SIZE);
105	paddr = pfn << PAGE_SHIFT;
106
107	if (memblock_is_region_memory(paddr, csize)) {
108		vaddr = __va(paddr);
109		csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
110	} else {
111		vaddr = ioremap_cache(paddr, PAGE_SIZE);
112		csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
113		iounmap(vaddr);
114	}
115
116	return csize;
117}
118
119#ifdef CONFIG_PPC_RTAS
120/*
121 * The crashkernel region will almost always overlap the RTAS region, so
122 * we have to be careful when shrinking the crashkernel region.
123 */
124void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
125{
126	unsigned long addr;
127	const __be32 *basep, *sizep;
128	unsigned int rtas_start = 0, rtas_end = 0;
129
130	basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
131	sizep = of_get_property(rtas.dev, "rtas-size", NULL);
132
133	if (basep && sizep) {
134		rtas_start = be32_to_cpup(basep);
135		rtas_end = rtas_start + be32_to_cpup(sizep);
136	}
137
138	for (addr = begin; addr < end; addr += PAGE_SIZE) {
139		/* Does this page overlap with the RTAS region? */
140		if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
141			continue;
142
143		free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
144	}
145}
146#endif