diff options
Diffstat (limited to 'arch/x86/mm/init.c')
| -rw-r--r-- | arch/x86/mm/init.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 8dacdb96899e..fd10d91a6115 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -6,6 +6,7 @@ #include <linux/swapfile.h> #include <linux/swapops.h> #include <linux/kmemleak.h> +#include <linux/sched/task.h> #include <asm/set_memory.h> #include <asm/e820/api.h> @@ -23,6 +24,7 @@ #include <asm/hypervisor.h> #include <asm/cpufeature.h> #include <asm/pti.h> +#include <asm/text-patching.h> /* * We need to define the tracepoints somewhere, and tlb.c @@ -702,6 +704,41 @@ void __init init_mem_mapping(void) } /* + * Initialize an mm_struct to be used during poking and a pointer to be used + * during patching. + */ +void __init poking_init(void) +{ + spinlock_t *ptl; + pte_t *ptep; + + poking_mm = copy_init_mm(); + BUG_ON(!poking_mm); + + /* + * Randomize the poking address, but make sure that the following page + * will be mapped at the same PMD. We need 2 pages, so find space for 3, + * and adjust the address if the PMD ends after the first one. + */ + poking_addr = TASK_UNMAPPED_BASE; + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) + poking_addr += (kaslr_get_random_long("Poking") & PAGE_MASK) % + (TASK_SIZE - TASK_UNMAPPED_BASE - 3 * PAGE_SIZE); + + if (((poking_addr + PAGE_SIZE) & ~PMD_MASK) == 0) + poking_addr += PAGE_SIZE; + + /* + * We need to trigger the allocation of the page-tables that will be + * needed for poking now. Later, poking may be performed in an atomic + * section, which might cause allocation to fail. + */ + ptep = get_locked_pte(poking_mm, poking_addr, &ptl); + BUG_ON(!ptep); + pte_unmap_unlock(ptep, ptl); +} + +/* * devmem_is_allowed() checks to see if /dev/mem access to a certain address * is valid. The argument is a physical page number. * |