/*
* Create PGD aligned trampoline table to allow real mode initialization
* of additional CPUs. Consume only 1 low memory page.
*/
void __meminit init_trampoline(void)
{
unsigned long paddr, paddr_next;
pgd_t *pgd;
pud_t *pud_page, *pud_page_tramp;
int i;
if (!kaslr_memory_enabled()) {
init_trampoline_default();
return;
}
pud_page_tramp = alloc_low_page();
paddr = 0;
pgd = pgd_offset_k((unsigned long)__va(paddr));
pud_page = (pud_t *) pgd_page_vaddr(*pgd);
for (i = pud_index(paddr); i < PTRS_PER_PUD; i++, paddr = paddr_next) {
pud_t *pud, *pud_tramp;
unsigned long vaddr = (unsigned long)__va(paddr);
pud_tramp = pud_page_tramp + pud_index(paddr);
pud = pud_page + pud_index(vaddr);
paddr_next = (paddr & PUD_MASK) + PUD_SIZE;
*pud_tramp = *pud;
}
set_pgd(&trampoline_pgd_entry,
__pgd(_KERNPG_TABLE | __pa(pud_page_tramp)));
}
/*
* The real mode trampoline, which is required for bootstrapping CPUs
* occupies only a small area under the low 1MB. See reserve_real_mode()
* for details.
*
* If KASLR is disabled the first PGD entry of the direct mapping is copied
* to map the real mode trampoline.
*
* If KASLR is enabled, copy only the PUD which covers the low 1MB
* area. This limits the randomization granularity to 1GB for both 4-level
* and 5-level paging.
*/
void __meminit init_trampoline(void)
{
if (!kaslr_memory_enabled()) {
init_trampoline_default();
return;
}
init_trampoline_pud();
}
/* Initialize base and padding for each memory region randomized with KASLR */
void __init kernel_randomize_memory(void)
{
size_t i;
unsigned long vaddr_start, vaddr;
unsigned long rand, memory_tb;
struct rnd_state rand_state;
unsigned long remain_entropy;
vaddr_start = pgtable_l5_enabled() ? __PAGE_OFFSET_BASE_L5 : __PAGE_OFFSET_BASE_L4;
vaddr = vaddr_start;
/*
* These BUILD_BUG_ON checks ensure the memory layout is consistent
* with the vaddr_start/vaddr_end variables. These checks are very
* limited....
*/
BUILD_BUG_ON(vaddr_start >= vaddr_end);
BUILD_BUG_ON(vaddr_end != CPU_ENTRY_AREA_BASE);
BUILD_BUG_ON(vaddr_end > __START_KERNEL_map);
if (!kaslr_memory_enabled())
return;
kaslr_regions[0].size_tb = 1 << (MAX_PHYSMEM_BITS - TB_SHIFT);
kaslr_regions[1].size_tb = VMALLOC_SIZE_TB;
/*
* Update Physical memory mapping to available and
* add padding if needed (especially for memory hotplug support).
*/
BUG_ON(kaslr_regions[0].base != &page_offset_base);
memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) +
CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
/* Adapt phyiscal memory region size based on available memory */
if (memory_tb < kaslr_regions[0].size_tb)
kaslr_regions[0].size_tb = memory_tb;
/* Calculate entropy available between regions */
remain_entropy = vaddr_end - vaddr_start;
for (i = 0; i < ARRAY_SIZE(kaslr_regions); i++)
remain_entropy -= get_padding(&kaslr_regions[i]);
prandom_seed_state(&rand_state, kaslr_get_random_long("Memory"));
for (i = 0; i < ARRAY_SIZE(kaslr_regions); i++) {
unsigned long entropy;
/*
* Select a random virtual address using the extra entropy
* available.
*/
entropy = remain_entropy / (ARRAY_SIZE(kaslr_regions) - i);
prandom_bytes_state(&rand_state, &rand, sizeof(rand));
entropy = (rand % (entropy + 1)) & PUD_MASK;
vaddr += entropy;
*kaslr_regions[i].base = vaddr;
/*
* Jump the region and add a minimum padding based on
* randomization alignment.
*/
vaddr += get_padding(&kaslr_regions[i]);
vaddr = round_up(vaddr + 1, PUD_SIZE);
remain_entropy -= entropy;
}
}
/* Initialize base and padding for each memory region randomized with KASLR */
void __init kernel_randomize_memory(void)
{
size_t i;
unsigned long vaddr = vaddr_start;
unsigned long rand, memory_tb;
struct rnd_state rand_state;
unsigned long remain_entropy;
/*
* All these BUILD_BUG_ON checks ensures the memory layout is
* consistent with the vaddr_start/vaddr_end variables.
*/
BUILD_BUG_ON(vaddr_start >= vaddr_end);
BUILD_BUG_ON(IS_ENABLED(CONFIG_X86_ESPFIX64) &&
vaddr_end >= EFI_VA_END);
BUILD_BUG_ON((IS_ENABLED(CONFIG_X86_ESPFIX64) ||
IS_ENABLED(CONFIG_EFI)) &&
vaddr_end >= __START_KERNEL_map);
BUILD_BUG_ON(vaddr_end > __START_KERNEL_map);
if (!kaslr_memory_enabled())
return;
/*
* Update Physical memory mapping to available and
* add padding if needed (especially for memory hotplug support).
*/
BUG_ON(kaslr_regions[0].base != &page_offset_base);
memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) +
CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
/* Adapt phyiscal memory region size based on available memory */
if (memory_tb < kaslr_regions[0].size_tb)
kaslr_regions[0].size_tb = memory_tb;
/* Calculate entropy available between regions */
remain_entropy = vaddr_end - vaddr_start;
for (i = 0; i < ARRAY_SIZE(kaslr_regions); i++)
remain_entropy -= get_padding(&kaslr_regions[i]);
prandom_seed_state(&rand_state, kaslr_get_random_long("Memory"));
for (i = 0; i < ARRAY_SIZE(kaslr_regions); i++) {
unsigned long entropy;
/*
* Select a random virtual address using the extra entropy
* available.
*/
entropy = remain_entropy / (ARRAY_SIZE(kaslr_regions) - i);
prandom_bytes_state(&rand_state, &rand, sizeof(rand));
entropy = (rand % (entropy + 1)) & PUD_MASK;
vaddr += entropy;
*kaslr_regions[i].base = vaddr;
/*
* Jump the region and add a minimum padding based on
* randomization alignment.
*/
vaddr += get_padding(&kaslr_regions[i]);
vaddr = round_up(vaddr + 1, PUD_SIZE);
remain_entropy -= entropy;
}
}