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484a418d07
Dave noticed that when specifying multiple efi_fake_mem= entries only
the last entry was successfully being reflected in the efi memory map.
This is due to the fact that the efi_memmap_insert() is being called
multiple times, but on successive invocations the insertion should be
applied to the last new memmap rather than the original map at
efi_fake_memmap() entry.
Rework efi_fake_memmap() to install the new memory map after each
efi_fake_mem= entry is parsed.
This also fixes an issue in efi_fake_memmap() that caused it to litter
emtpy entries into the end of the efi memory map. An empty entry causes
efi_memmap_insert() to attempt more memmap splits / copies than
efi_memmap_split_count() accounted for when sizing the new map. When
that happens efi_memmap_insert() may overrun its allocation, and if you
are lucky will spill over to an unmapped page leading to crash
signature like the following rather than silent corruption:
BUG: unable to handle page fault for address: ffffffffff281000
[..]
RIP: 0010:efi_memmap_insert+0x11d/0x191
[..]
Call Trace:
? bgrt_init+0xbe/0xbe
? efi_arch_mem_reserve+0x1cb/0x228
? acpi_parse_bgrt+0xa/0xd
? acpi_table_parse+0x86/0xb8
? acpi_boot_init+0x494/0x4e3
? acpi_parse_x2apic+0x87/0x87
? setup_acpi_sci+0xa2/0xa2
? setup_arch+0x8db/0x9e1
? start_kernel+0x6a/0x547
? secondary_startup_64+0xb6/0xc0
Commit af16489848 "x86/efi: Update e820 with reserved EFI boot
services data to fix kexec breakage" introduced more occurrences where
efi_memmap_insert() is invoked after an efi_fake_mem= configuration has
been parsed. Previously the side effects of vestigial empty entries were
benign, but with commit af16489848 that follow-on efi_memmap_insert()
invocation triggers efi_memmap_insert() overruns.
Reported-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20191231014630.GA24942@dhcp-128-65.nay.redhat.com
Link: https://lore.kernel.org/r/20200113172245.27925-14-ardb@kernel.org
125 lines
2.8 KiB
C
125 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fake_mem.c
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*
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* Copyright (C) 2015 FUJITSU LIMITED
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* Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
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*
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* This code introduces new boot option named "efi_fake_mem"
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* By specifying this parameter, you can add arbitrary attribute to
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* specific memory range by updating original (firmware provided) EFI
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* memmap.
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*/
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#include <linux/kernel.h>
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#include <linux/efi.h>
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#include <linux/init.h>
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#include <linux/memblock.h>
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#include <linux/types.h>
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#include <linux/sort.h>
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#include "fake_mem.h"
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struct efi_mem_range efi_fake_mems[EFI_MAX_FAKEMEM];
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int nr_fake_mem;
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static int __init cmp_fake_mem(const void *x1, const void *x2)
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{
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const struct efi_mem_range *m1 = x1;
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const struct efi_mem_range *m2 = x2;
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if (m1->range.start < m2->range.start)
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return -1;
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if (m1->range.start > m2->range.start)
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return 1;
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return 0;
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}
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static void __init efi_fake_range(struct efi_mem_range *efi_range)
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{
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struct efi_memory_map_data data = { 0 };
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int new_nr_map = efi.memmap.nr_map;
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efi_memory_desc_t *md;
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void *new_memmap;
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/* count up the number of EFI memory descriptor */
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for_each_efi_memory_desc(md)
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new_nr_map += efi_memmap_split_count(md, &efi_range->range);
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/* allocate memory for new EFI memmap */
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if (efi_memmap_alloc(new_nr_map, &data) != 0)
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return;
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/* create new EFI memmap */
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new_memmap = early_memremap(data.phys_map, data.size);
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if (!new_memmap) {
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__efi_memmap_free(data.phys_map, data.size, data.flags);
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return;
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}
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efi_memmap_insert(&efi.memmap, new_memmap, efi_range);
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/* swap into new EFI memmap */
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early_memunmap(new_memmap, data.size);
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efi_memmap_install(&data);
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}
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void __init efi_fake_memmap(void)
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{
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int i;
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if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
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return;
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for (i = 0; i < nr_fake_mem; i++)
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efi_fake_range(&efi_fake_mems[i]);
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/* print new EFI memmap */
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efi_print_memmap();
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}
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static int __init setup_fake_mem(char *p)
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{
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u64 start = 0, mem_size = 0, attribute = 0;
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int i;
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if (!p)
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return -EINVAL;
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while (*p != '\0') {
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mem_size = memparse(p, &p);
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if (*p == '@')
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start = memparse(p+1, &p);
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else
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break;
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if (*p == ':')
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attribute = simple_strtoull(p+1, &p, 0);
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else
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break;
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if (nr_fake_mem >= EFI_MAX_FAKEMEM)
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break;
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efi_fake_mems[nr_fake_mem].range.start = start;
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efi_fake_mems[nr_fake_mem].range.end = start + mem_size - 1;
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efi_fake_mems[nr_fake_mem].attribute = attribute;
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nr_fake_mem++;
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if (*p == ',')
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p++;
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}
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sort(efi_fake_mems, nr_fake_mem, sizeof(struct efi_mem_range),
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cmp_fake_mem, NULL);
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for (i = 0; i < nr_fake_mem; i++)
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pr_info("efi_fake_mem: add attr=0x%016llx to [mem 0x%016llx-0x%016llx]",
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efi_fake_mems[i].attribute, efi_fake_mems[i].range.start,
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efi_fake_mems[i].range.end);
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return *p == '\0' ? 0 : -EINVAL;
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}
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early_param("efi_fake_mem", setup_fake_mem);
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