diff options
Diffstat (limited to 'arch/x86/mm/kaslr.c')
| -rw-r--r-- | arch/x86/mm/kaslr.c | 32 |
1 files changed, 9 insertions, 23 deletions
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c index 879ef930e2c2..aedebd2ebf1e 100644 --- a/arch/x86/mm/kaslr.c +++ b/arch/x86/mm/kaslr.c @@ -34,25 +34,14 @@ #define TB_SHIFT 40 /* - * Virtual address start and end range for randomization. The end changes base - * on configuration to have the highest amount of space for randomization. - * It increases the possible random position for each randomized region. + * Virtual address start and end range for randomization. * - * You need to add an if/def entry if you introduce a new memory region - * compatible with KASLR. Your entry must be in logical order with memory - * layout. For example, ESPFIX is before EFI because its virtual address is - * before. You also need to add a BUILD_BUG_ON() in kernel_randomize_memory() to - * ensure that this order is correct and won't be changed. + * The end address could depend on more configuration options to make the + * highest amount of space for randomization available, but that's too hard + * to keep straight and caused issues already. */ static const unsigned long vaddr_start = __PAGE_OFFSET_BASE; - -#if defined(CONFIG_X86_ESPFIX64) -static const unsigned long vaddr_end = ESPFIX_BASE_ADDR; -#elif defined(CONFIG_EFI) -static const unsigned long vaddr_end = EFI_VA_END; -#else -static const unsigned long vaddr_end = __START_KERNEL_map; -#endif +static const unsigned long vaddr_end = CPU_ENTRY_AREA_BASE; /* Default values */ unsigned long page_offset_base = __PAGE_OFFSET_BASE; @@ -101,15 +90,12 @@ void __init kernel_randomize_memory(void) unsigned long remain_entropy; /* - * All these BUILD_BUG_ON checks ensures the memory layout is - * consistent with the vaddr_start/vaddr_end variables. + * 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(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 != CPU_ENTRY_AREA_BASE); BUILD_BUG_ON(vaddr_end > __START_KERNEL_map); if (!kaslr_memory_enabled()) |