[PATCHv2 01/10] x86/kasan: Use the same shadow offset for 4- and 5-level paging
From: Kirill A. Shutemov
Date: Tue Jul 18 2017 - 10:21:51 EST
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 setup.
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
[kirill.shutemov@xxxxxxxxxxxxxxx: clenaup, changelog message]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 1 -
arch/x86/kernel/Makefile | 3 +-
arch/x86/mm/kasan_init_64.c | 86 ++++++++++++++++++++++++++++++++++-----------
3 files changed, 67 insertions(+), 23 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index add693b0239e..4f94fda5dba5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -299,7 +299,6 @@ config ARCH_SUPPORTS_DEBUG_PAGEALLOC
config KASAN_SHADOW_OFFSET
hex
depends on KASAN
- default 0xdff8000000000000 if X86_5LEVEL
default 0xdffffc0000000000
config HAVE_INTEL_TXT
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index a01892bdd61a..7f67b8316be0 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -24,7 +24,8 @@ 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_head_$(BITS).o := y
OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o := y
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 02c9d7553409..0691cc0f91ac 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -15,6 +15,8 @@
extern pgd_t early_top_pgt[PTRS_PER_PGD];
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;
@@ -30,8 +32,9 @@ static void __init clear_pgds(unsigned long start,
unsigned long end)
{
pgd_t *pgd;
+ 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()
@@ -42,29 +45,60 @@ static void __init clear_pgds(unsigned long start,
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;
+ 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
@@ -101,7 +135,7 @@ 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);
@@ -117,12 +151,22 @@ void __init kasan_init(void)
#endif
memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
+
+ 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++) {
--
2.11.0