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// SPDX-License-Identifier: GPL-2.0
/*
* fake_mem.c
*
* Copyright (C) 2015 FUJITSU LIMITED
* Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
*
* This code introduces new boot option named "efi_fake_mem"
* By specifying this parameter, you can add arbitrary attribute to
* specific memory range by updating original (firmware provided) EFI
* memmap.
*/
#include <linux/kernel.h>
#include <linux/efi.h>
#include <linux/init.h>
#include <linux/memblock.h>
#include <linux/types.h>
#include <linux/sort.h>
#include <asm/e820/api.h>
#include <asm/efi.h>
#define EFI_MAX_FAKEMEM CONFIG_EFI_MAX_FAKE_MEM
static struct efi_mem_range efi_fake_mems[EFI_MAX_FAKEMEM];
static int nr_fake_mem;
static int __init cmp_fake_mem(const void *x1, const void *x2)
{
const struct efi_mem_range *m1 = x1;
const struct efi_mem_range *m2 = x2;
if (m1->range.start < m2->range.start)
return -1;
if (m1->range.start > m2->range.start)
return 1;
return 0;
}
static void __init efi_fake_range(struct efi_mem_range *efi_range)
{
struct efi_memory_map_data data = { 0 };
int new_nr_map = efi.memmap.nr_map;
efi_memory_desc_t *md;
void *new_memmap;
/* count up the number of EFI memory descriptor */
for_each_efi_memory_desc(md)
new_nr_map += efi_memmap_split_count(md, &efi_range->range);
/* allocate memory for new EFI memmap */
if (efi_memmap_alloc(new_nr_map, &data) != 0)
return;
/* create new EFI memmap */
new_memmap = early_memremap(data.phys_map, data.size);
if (!new_memmap) {
__efi_memmap_free(data.phys_map, data.size, data.flags);
return;
}
efi_memmap_insert(&efi.memmap, new_memmap, efi_range);
/* swap into new EFI memmap */
early_memunmap(new_memmap, data.size);
efi_memmap_install(&data);
}
void __init efi_fake_memmap(void)
{
int i;
if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
return;
for (i = 0; i < nr_fake_mem; i++)
efi_fake_range(&efi_fake_mems[i]);
/* print new EFI memmap */
efi_print_memmap();
}
static int __init setup_fake_mem(char *p)
{
u64 start = 0, mem_size = 0, attribute = 0;
int i;
if (!p)
return -EINVAL;
while (*p != '\0') {
mem_size = memparse(p, &p);
if (*p == '@')
start = memparse(p+1, &p);
else
break;
if (*p == ':')
attribute = simple_strtoull(p+1, &p, 0);
else
break;
if (nr_fake_mem >= EFI_MAX_FAKEMEM)
break;
efi_fake_mems[nr_fake_mem].range.start = start;
efi_fake_mems[nr_fake_mem].range.end = start + mem_size - 1;
efi_fake_mems[nr_fake_mem].attribute = attribute;
nr_fake_mem++;
if (*p == ',')
p++;
}
sort(efi_fake_mems, nr_fake_mem, sizeof(struct efi_mem_range),
cmp_fake_mem, NULL);
for (i = 0; i < nr_fake_mem; i++)
pr_info("efi_fake_mem: add attr=0x%016llx to [mem 0x%016llx-0x%016llx]",
efi_fake_mems[i].attribute, efi_fake_mems[i].range.start,
efi_fake_mems[i].range.end);
return *p == '\0' ? 0 : -EINVAL;
}
early_param("efi_fake_mem", setup_fake_mem);
void __init efi_fake_memmap_early(void)
{
int i;
/*
* The late efi_fake_mem() call can handle all requests if
* EFI_MEMORY_SP support is disabled.
*/
if (!efi_soft_reserve_enabled())
return;
if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
return;
/*
* Given that efi_fake_memmap() needs to perform memblock
* allocations it needs to run after e820__memblock_setup().
* However, if efi_fake_mem specifies EFI_MEMORY_SP for a given
* address range that potentially needs to mark the memory as
* reserved prior to e820__memblock_setup(). Update e820
* directly if EFI_MEMORY_SP is specified for an
* EFI_CONVENTIONAL_MEMORY descriptor.
*/
for (i = 0; i < nr_fake_mem; i++) {
struct efi_mem_range *mem = &efi_fake_mems[i];
efi_memory_desc_t *md;
u64 m_start, m_end;
if ((mem->attribute & EFI_MEMORY_SP) == 0)
continue;
m_start = mem->range.start;
m_end = mem->range.end;
for_each_efi_memory_desc(md) {
u64 start, end, size;
if (md->type != EFI_CONVENTIONAL_MEMORY)
continue;
start = md->phys_addr;
end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
if (m_start <= end && m_end >= start)
/* fake range overlaps descriptor */;
else
continue;
/*
* Trim the boundary of the e820 update to the
* descriptor in case the fake range overlaps
* !EFI_CONVENTIONAL_MEMORY
*/
start = max(start, m_start);
end = min(end, m_end);
size = end - start + 1;
if (end <= start)
continue;
/*
* Ensure each efi_fake_mem instance results in
* a unique e820 resource
*/
e820__range_remove(start, size, E820_TYPE_RAM, 1);
e820__range_add(start, size, E820_TYPE_SOFT_RESERVED);
e820__update_table(e820_table);
}
}
}
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