diff options
| -rw-r--r-- | arch/x86/include/asm/pgtable.h | 3 | ||||
| -rw-r--r-- | arch/x86/include/asm/text-patching.h | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/alternative.c | 3 | ||||
| -rw-r--r-- | arch/x86/mm/init.c | 37 | ||||
| -rw-r--r-- | init/main.c | 3 |
5 files changed, 48 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 2779ace16d23..702db5904753 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -1021,6 +1021,9 @@ static inline void __meminit init_trampoline_default(void) /* Default trampoline pgd value */ trampoline_pgd_entry = init_top_pgt[pgd_index(__PAGE_OFFSET)]; } + +void __init poking_init(void); + # ifdef CONFIG_RANDOMIZE_MEMORY void __meminit init_trampoline(void); # else diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h index f8fc8e86cf01..a75eed841eed 100644 --- a/arch/x86/include/asm/text-patching.h +++ b/arch/x86/include/asm/text-patching.h @@ -39,5 +39,7 @@ extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len); extern int poke_int3_handler(struct pt_regs *regs); extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler); extern int after_bootmem; +extern __ro_after_init struct mm_struct *poking_mm; +extern __ro_after_init unsigned long poking_addr; #endif /* _ASM_X86_TEXT_PATCHING_H */ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 0a814d73547a..11d5c710a94f 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -679,6 +679,9 @@ void *__init_or_module text_poke_early(void *addr, const void *opcode, return addr; } +__ro_after_init struct mm_struct *poking_mm; +__ro_after_init unsigned long poking_addr; + static void *__text_poke(void *addr, const void *opcode, size_t len) { unsigned long flags; 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. * diff --git a/init/main.c b/init/main.c index 7d4025d665eb..95dd9406ee31 100644 --- a/init/main.c +++ b/init/main.c @@ -504,6 +504,8 @@ void __init __weak thread_stack_cache_init(void) void __init __weak mem_encrypt_init(void) { } +void __init __weak poking_init(void) { } + bool initcall_debug; core_param(initcall_debug, initcall_debug, bool, 0644); @@ -737,6 +739,7 @@ asmlinkage __visible void __init start_kernel(void) taskstats_init_early(); delayacct_init(); + poking_init(); check_bugs(); acpi_subsystem_init(); |