From 0609ae011deb41c9629b7f5fd626dfa1ac9d16b0 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Sat, 30 Nov 2019 17:55:00 -0800 Subject: x86/kasan: support KASAN_VMALLOC In the case where KASAN directly allocates memory to back vmalloc space, don't map the early shadow page over it. We prepopulate pgds/p4ds for the range that would otherwise be empty. This is required to get it synced to hardware on boot, allowing the lower levels of the page tables to be filled dynamically. Link: http://lkml.kernel.org/r/20191031093909.9228-5-dja@axtens.net Signed-off-by: Daniel Axtens Acked-by: Dmitry Vyukov Reviewed-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Christophe Leroy Cc: Mark Rutland Cc: Vasily Gorbik Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/Kconfig | 1 + arch/x86/mm/kasan_init_64.c | 61 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 62 insertions(+) (limited to 'arch') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 0cb1756223be..5e8949953660 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -134,6 +134,7 @@ config X86 select HAVE_ARCH_JUMP_LABEL select HAVE_ARCH_JUMP_LABEL_RELATIVE select HAVE_ARCH_KASAN if X86_64 + select HAVE_ARCH_KASAN_VMALLOC if X86_64 select HAVE_ARCH_KGDB select HAVE_ARCH_MMAP_RND_BITS if MMU select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 296da58f3013..cf5bc37c90ac 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -245,6 +245,49 @@ static void __init kasan_map_early_shadow(pgd_t *pgd) } while (pgd++, addr = next, addr != end); } +static void __init kasan_shallow_populate_p4ds(pgd_t *pgd, + unsigned long addr, + unsigned long end) +{ + p4d_t *p4d; + unsigned long next; + void *p; + + p4d = p4d_offset(pgd, addr); + do { + next = p4d_addr_end(addr, end); + + if (p4d_none(*p4d)) { + p = early_alloc(PAGE_SIZE, NUMA_NO_NODE, true); + p4d_populate(&init_mm, p4d, p); + } + } while (p4d++, addr = next, addr != end); +} + +static void __init kasan_shallow_populate_pgds(void *start, void *end) +{ + unsigned long addr, next; + pgd_t *pgd; + void *p; + + addr = (unsigned long)start; + pgd = pgd_offset_k(addr); + do { + next = pgd_addr_end(addr, (unsigned long)end); + + if (pgd_none(*pgd)) { + p = early_alloc(PAGE_SIZE, NUMA_NO_NODE, true); + pgd_populate(&init_mm, pgd, p); + } + + /* + * we need to populate p4ds to be synced when running in + * four level mode - see sync_global_pgds_l4() + */ + kasan_shallow_populate_p4ds(pgd, addr, next); + } while (pgd++, addr = next, addr != (unsigned long)end); +} + #ifdef CONFIG_KASAN_INLINE static int kasan_die_handler(struct notifier_block *self, unsigned long val, @@ -354,6 +397,24 @@ void __init kasan_init(void) kasan_populate_early_shadow( kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM), + kasan_mem_to_shadow((void *)VMALLOC_START)); + + /* + * If we're in full vmalloc mode, don't back vmalloc space with early + * shadow pages. Instead, prepopulate pgds/p4ds so they are synced to + * the global table and we can populate the lower levels on demand. + */ + if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) + kasan_shallow_populate_pgds( + kasan_mem_to_shadow((void *)VMALLOC_START), + kasan_mem_to_shadow((void *)VMALLOC_END)); + else + kasan_populate_early_shadow( + kasan_mem_to_shadow((void *)VMALLOC_START), + kasan_mem_to_shadow((void *)VMALLOC_END)); + + kasan_populate_early_shadow( + kasan_mem_to_shadow((void *)VMALLOC_END + 1), shadow_cpu_entry_begin); kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin, -- cgit v1.2.3-59-g8ed1b