Use the upper half of the virtual address space so that 5-level paging
doesn't collide with the core infrastucture in the top-level PTE, which
hides bugs, e.g. SMEP + 5-level, and is generally a nightmare to debug.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
x86/access.c | 50 ++++++++++++++++++++++++++++++--------------------
1 file changed, 30 insertions(+), 20 deletions(-)
diff --git a/x86/access.c b/x86/access.c
index 5bd446c..6ccdb76 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -34,7 +34,7 @@ static int invalid_mask;
#define EFER_NX_MASK (1ull << 11)
#define PT_INDEX(address, level) \
- ((address) >> (12 + ((level)-1) * 9)) & 511
+ (((address) >> (12 + ((level)-1) * 9)) & 511)
/*
* page table access check tests
@@ -340,12 +340,21 @@ static void ac_test_reset_pt_pool(ac_pt_env_t *pt_env)
pt_env->pt_pool_current = 0;
}
-static void ac_test_init(ac_test_t *at, void *virt, ac_pt_env_t *pt_env)
+static void ac_test_init(ac_test_t *at, unsigned long virt, ac_pt_env_t *pt_env)
{
+ /*
+ * The KUT infrastructure, e.g. this function, must use a different
+ * top-level SPTE than the test, otherwise modifying SPTEs can affect
+ * normal behavior, e.g. crash the test due to marking code SPTEs
+ * USER when CR4.SMEP=1.
+ */
+ assert(PT_INDEX(virt, pt_env->pt_levels) !=
+ PT_INDEX((unsigned long)ac_test_init, pt_env->pt_levels));
+
set_efer_nx(1);
set_cr0_wp(1);
at->flags = 0;
- at->virt = virt;
+ at->virt = (void *)virt;
at->phys = AT_CODE_DATA_PHYS;
at->pt_levels = pt_env->pt_levels;
}
@@ -571,12 +580,13 @@ static void __ac_setup_specific_pages(ac_test_t *at, ac_pt_env_t *pt_env, bool r
pt_element_t pte;
/*
- * Reuse existing page tables along the path to the test code and data
- * (which is in the bottom 2MB).
+ * Reuse existing page tables along the highest index, some
+ * tests rely on sharing upper level paging structures between
+ * two separate sub-tests.
*/
- if (skip && i >= 2 && index == 0) {
+ if (skip && i >= 2 && index == 511 && (*ptep & PT_PRESENT_MASK))
goto next;
- }
+
skip = false;
if (reuse && *ptep) {
switch (i) {
@@ -863,8 +873,8 @@ static int corrupt_hugepage_triger(ac_pt_env_t *pt_env)
{
ac_test_t at1, at2;
- ac_test_init(&at1, (void *)(0x123400000000), pt_env);
- ac_test_init(&at2, (void *)(0x666600000000), pt_env);
+ ac_test_init(&at1, 0xffff923400000000ul, pt_env);
+ ac_test_init(&at2, 0xffffe66600000000ul, pt_env);
at2.flags = AC_CPU_CR0_WP_MASK | AC_PDE_PSE_MASK | AC_PDE_PRESENT_MASK;
ac_test_setup_pte(&at2, pt_env);
@@ -901,8 +911,8 @@ static int check_pfec_on_prefetch_pte(ac_pt_env_t *pt_env)
{
ac_test_t at1, at2;
- ac_test_init(&at1, (void *)(0x123406001000), pt_env);
- ac_test_init(&at2, (void *)(0x123406003000), pt_env);
+ ac_test_init(&at1, 0xffff923406001000ul, pt_env);
+ ac_test_init(&at2, 0xffff923406003000ul, pt_env);
at1.flags = AC_PDE_PRESENT_MASK | AC_PTE_PRESENT_MASK;
ac_setup_specific_pages(&at1, pt_env, 30 * 1024 * 1024, 30 * 1024 * 1024);
@@ -946,8 +956,8 @@ static int check_large_pte_dirty_for_nowp(ac_pt_env_t *pt_env)
{
ac_test_t at1, at2;
- ac_test_init(&at1, (void *)(0x123403000000), pt_env);
- ac_test_init(&at2, (void *)(0x666606000000), pt_env);
+ ac_test_init(&at1, 0xffff923403000000ul, pt_env);
+ ac_test_init(&at2, 0xffffe66606000000ul, pt_env);
at2.flags = AC_PDE_PRESENT_MASK | AC_PDE_PSE_MASK;
ac_test_setup_pte(&at2, pt_env);
@@ -985,7 +995,7 @@ static int check_smep_andnot_wp(ac_pt_env_t *pt_env)
return 1;
}
- ac_test_init(&at1, (void *)(0x123406001000), pt_env);
+ ac_test_init(&at1, 0xffff923406001000ul, pt_env);
at1.flags = AC_PDE_PRESENT_MASK | AC_PTE_PRESENT_MASK |
AC_PDE_USER_MASK | AC_PTE_USER_MASK |
@@ -1028,7 +1038,7 @@ err:
static int check_effective_sp_permissions(ac_pt_env_t *pt_env)
{
- unsigned long ptr1 = 0x123480000000;
+ unsigned long ptr1 = 0xffff923480000000;
unsigned long ptr2 = ptr1 + SZ_2M;
unsigned long ptr3 = ptr1 + SZ_1G;
unsigned long ptr4 = ptr3 + SZ_2M;
@@ -1047,22 +1057,22 @@ static int check_effective_sp_permissions(ac_pt_env_t *pt_env)
* pud1 and pud2 point to the same pmd page.
*/
- ac_test_init(&at1, (void *)(ptr1), pt_env);
+ ac_test_init(&at1, ptr1, pt_env);
at1.flags = AC_PDE_PRESENT_MASK | AC_PTE_PRESENT_MASK |
AC_PDE_USER_MASK | AC_PTE_USER_MASK |
AC_PDE_ACCESSED_MASK | AC_PTE_ACCESSED_MASK |
AC_PTE_WRITABLE_MASK | AC_ACCESS_USER_MASK;
__ac_setup_specific_pages(&at1, pt_env, false, pmd, 0);
- ac_test_init(&at2, (void *)(ptr2), pt_env);
+ ac_test_init(&at2, ptr2, pt_env);
at2.flags = at1.flags | AC_PDE_WRITABLE_MASK | AC_PTE_DIRTY_MASK | AC_ACCESS_WRITE_MASK;
__ac_setup_specific_pages(&at2, pt_env, true, pmd, 0);
- ac_test_init(&at3, (void *)(ptr3), pt_env);
+ ac_test_init(&at3, ptr3, pt_env);
at3.flags = AC_PDPTE_NO_WRITABLE_MASK | at1.flags;
__ac_setup_specific_pages(&at3, pt_env, true, pmd, 0);
- ac_test_init(&at4, (void *)(ptr4), pt_env);
+ ac_test_init(&at4, ptr4, pt_env);
at4.flags = AC_PDPTE_NO_WRITABLE_MASK | at2.flags;
__ac_setup_specific_pages(&at4, pt_env, true, pmd, 0);
@@ -1139,7 +1149,7 @@ int ac_test_run(int pt_levels)
}
ac_env_int(&pt_env, pt_levels);
- ac_test_init(&at, (void *)(0x123400000000), &pt_env);
+ ac_test_init(&at, 0xffff923400000000ul, &pt_env);
if (this_cpu_has(X86_FEATURE_PKU)) {
set_cr4_pke(1);
--
2.34.0.rc2.393.gf8c9666880-goog
