This is a note to let you know that I've just added the patch titled
x86/kasan: Use the same shadow offset for 4- and 5-level paging
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: x86-kasan-use-the-same-shadow-offset-for-4-and-5-level-paging.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 12a8cc7fcf54a8575f094be1e99032ec38aa045c Mon Sep 17 00:00:00 2001
From: Andrey Ryabinin aryabinin@virtuozzo.com Date: Fri, 29 Sep 2017 17:08:18 +0300 Subject: x86/kasan: Use the same shadow offset for 4- and 5-level paging
From: Andrey Ryabinin aryabinin@virtuozzo.com
commit 12a8cc7fcf54a8575f094be1e99032ec38aa045c upstream.
We are going to support boot-time switching between 4- and 5-level paging. For KASAN it means we cannot have different KASAN_SHADOW_OFFSET for different paging modes: the constant is passed to gcc to generate code and cannot be changed at runtime.
This patch changes KASAN code to use 0xdffffc0000000000 as shadow offset for both 4- and 5-level paging.
For 5-level paging it means that shadow memory region is not aligned to PGD boundary anymore and we have to handle unaligned parts of the region properly.
In addition, we have to exclude paravirt code from KASAN instrumentation as we now use set_pgd() before KASAN is fully ready.
[kirill.shutemov@linux.intel.com: clenaup, changelog message] Signed-off-by: Andrey Ryabinin aryabinin@virtuozzo.com Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Andy Lutomirski luto@amacapital.net Cc: Borislav Petkov bp@suse.de Cc: Cyrill Gorcunov gorcunov@openvz.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20170929140821.37654-4-kirill.shutemov@linux.intel.... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- Documentation/x86/x86_64/mm.txt | 2 arch/x86/Kconfig | 1 arch/x86/kernel/Makefile | 3 - arch/x86/mm/kasan_init_64.c | 101 +++++++++++++++++++++++++++++++--------- 4 files changed, 83 insertions(+), 24 deletions(-)
--- a/Documentation/x86/x86_64/mm.txt +++ b/Documentation/x86/x86_64/mm.txt @@ -34,7 +34,7 @@ ff92000000000000 - ffd1ffffffffffff (=54 ffd2000000000000 - ffd3ffffffffffff (=49 bits) hole ffd4000000000000 - ffd5ffffffffffff (=49 bits) virtual memory map (512TB) ... unused hole ... -ffd8000000000000 - fff7ffffffffffff (=53 bits) kasan shadow memory (8PB) +ffdf000000000000 - fffffc0000000000 (=53 bits) kasan shadow memory (8PB) ... unused hole ... ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks ... unused hole ... --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -303,7 +303,6 @@ config ARCH_SUPPORTS_DEBUG_PAGEALLOC config KASAN_SHADOW_OFFSET hex depends on KASAN - default 0xdff8000000000000 if X86_5LEVEL default 0xdffffc0000000000
config HAVE_INTEL_TXT --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -25,7 +25,8 @@ endif KASAN_SANITIZE_head$(BITS).o := n KASAN_SANITIZE_dumpstack.o := n KASAN_SANITIZE_dumpstack_$(BITS).o := n -KASAN_SANITIZE_stacktrace.o := n +KASAN_SANITIZE_stacktrace.o := n +KASAN_SANITIZE_paravirt.o := n
OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o := y OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o := y --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -16,6 +16,8 @@
extern struct range pfn_mapped[E820_MAX_ENTRIES];
+static p4d_t tmp_p4d_table[PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE); + static int __init map_range(struct range *range) { unsigned long start; @@ -31,8 +33,10 @@ static void __init clear_pgds(unsigned l unsigned long end) { pgd_t *pgd; + /* See comment in kasan_init() */ + unsigned long pgd_end = end & PGDIR_MASK;
- for (; start < end; start += PGDIR_SIZE) { + for (; start < pgd_end; start += PGDIR_SIZE) { pgd = pgd_offset_k(start); /* * With folded p4d, pgd_clear() is nop, use p4d_clear() @@ -43,29 +47,61 @@ static void __init clear_pgds(unsigned l else pgd_clear(pgd); } + + pgd = pgd_offset_k(start); + for (; start < end; start += P4D_SIZE) + p4d_clear(p4d_offset(pgd, start)); +} + +static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr) +{ + unsigned long p4d; + + if (!IS_ENABLED(CONFIG_X86_5LEVEL)) + return (p4d_t *)pgd; + + p4d = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK; + p4d += __START_KERNEL_map - phys_base; + return (p4d_t *)p4d + p4d_index(addr); +} + +static void __init kasan_early_p4d_populate(pgd_t *pgd, + unsigned long addr, + unsigned long end) +{ + pgd_t pgd_entry; + p4d_t *p4d, p4d_entry; + unsigned long next; + + if (pgd_none(*pgd)) { + pgd_entry = __pgd(_KERNPG_TABLE | __pa_nodebug(kasan_zero_p4d)); + set_pgd(pgd, pgd_entry); + } + + p4d = early_p4d_offset(pgd, addr); + do { + next = p4d_addr_end(addr, end); + + if (!p4d_none(*p4d)) + continue; + + p4d_entry = __p4d(_KERNPG_TABLE | __pa_nodebug(kasan_zero_pud)); + set_p4d(p4d, p4d_entry); + } while (p4d++, addr = next, addr != end && p4d_none(*p4d)); }
static void __init kasan_map_early_shadow(pgd_t *pgd) { - int i; - unsigned long start = KASAN_SHADOW_START; + /* See comment in kasan_init() */ + unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK; unsigned long end = KASAN_SHADOW_END; + unsigned long next;
- for (i = pgd_index(start); start < end; i++) { - switch (CONFIG_PGTABLE_LEVELS) { - case 4: - pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud) | - _KERNPG_TABLE); - break; - case 5: - pgd[i] = __pgd(__pa_nodebug(kasan_zero_p4d) | - _KERNPG_TABLE); - break; - default: - BUILD_BUG(); - } - start += PGDIR_SIZE; - } + pgd += pgd_index(addr); + do { + next = pgd_addr_end(addr, end); + kasan_early_p4d_populate(pgd, addr, next); + } while (pgd++, addr = next, addr != end); }
#ifdef CONFIG_KASAN_INLINE @@ -102,7 +138,7 @@ void __init kasan_early_init(void) for (i = 0; i < PTRS_PER_PUD; i++) kasan_zero_pud[i] = __pud(pud_val);
- for (i = 0; CONFIG_PGTABLE_LEVELS >= 5 && i < PTRS_PER_P4D; i++) + for (i = 0; IS_ENABLED(CONFIG_X86_5LEVEL) && i < PTRS_PER_P4D; i++) kasan_zero_p4d[i] = __p4d(p4d_val);
kasan_map_early_shadow(early_top_pgt); @@ -118,12 +154,35 @@ void __init kasan_init(void) #endif
memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt)); + + /* + * We use the same shadow offset for 4- and 5-level paging to + * facilitate boot-time switching between paging modes. + * As result in 5-level paging mode KASAN_SHADOW_START and + * KASAN_SHADOW_END are not aligned to PGD boundary. + * + * KASAN_SHADOW_START doesn't share PGD with anything else. + * We claim whole PGD entry to make things easier. + * + * KASAN_SHADOW_END lands in the last PGD entry and it collides with + * bunch of things like kernel code, modules, EFI mapping, etc. + * We need to take extra steps to not overwrite them. + */ + if (IS_ENABLED(CONFIG_X86_5LEVEL)) { + void *ptr; + + ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END)); + memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table)); + set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)], + __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE)); + } + load_cr3(early_top_pgt); __flush_tlb_all();
- clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); + clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
- kasan_populate_zero_shadow((void *)KASAN_SHADOW_START, + kasan_populate_zero_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK), kasan_mem_to_shadow((void *)PAGE_OFFSET));
for (i = 0; i < E820_MAX_ENTRIES; i++) {
Patches currently in stable-queue which might be from aryabinin@virtuozzo.com are
queue-4.14/x86-kasan-use-the-same-shadow-offset-for-4-and-5-level-paging.patch