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https://github.com/torvalds/linux
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199c847176
Given that EFI_MEMORY_SP is platform BIOS policy decision for marking memory ranges as "reserved for a specific purpose" there will inevitably be scenarios where the BIOS omits the attribute in situations where it is desired. Unlike other attributes if the OS wants to reserve this memory from the kernel the reservation needs to happen early in init. So early, in fact, that it needs to happen before e820__memblock_setup() which is a pre-requisite for efi_fake_memmap() that wants to allocate memory for the updated table. Introduce an x86 specific efi_fake_memmap_early() that can search for attempts to set EFI_MEMORY_SP via efi_fake_mem and update the e820 table accordingly. The KASLR code that scans the command line looking for user-directed memory reservations also needs to be updated to consider "efi_fake_mem=nn@ss:0x40000" requests. Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
126 lines
2.8 KiB
C
126 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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void __init efi_fake_memmap(void)
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{
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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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phys_addr_t new_memmap_phy;
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void *new_memmap;
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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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/* count up the number of EFI memory descriptor */
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for (i = 0; i < nr_fake_mem; i++) {
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for_each_efi_memory_desc(md) {
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struct range *r = &efi_fake_mems[i].range;
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new_nr_map += efi_memmap_split_count(md, r);
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}
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}
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/* allocate memory for new EFI memmap */
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new_memmap_phy = efi_memmap_alloc(new_nr_map);
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if (!new_memmap_phy)
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return;
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/* create new EFI memmap */
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new_memmap = early_memremap(new_memmap_phy,
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efi.memmap.desc_size * new_nr_map);
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if (!new_memmap) {
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memblock_free(new_memmap_phy, efi.memmap.desc_size * new_nr_map);
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return;
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}
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for (i = 0; i < nr_fake_mem; i++)
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efi_memmap_insert(&efi.memmap, new_memmap, &efi_fake_mems[i]);
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/* swap into new EFI memmap */
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early_memunmap(new_memmap, efi.memmap.desc_size * new_nr_map);
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efi_memmap_install(new_memmap_phy, new_nr_map);
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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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