This change to the PDPT (needed to ensure that the code runs from a
kernel page) is done everywhere CR4.SMEP is changed, because otherwise
access.c would crash as soon as CR4.SMEP is set. Centralize it at
the same place where CR4.SMEP is modified.
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
x86/access.c | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)
diff --git a/x86/access.c b/x86/access.c
index f9cbc7e..2f375eb 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -167,11 +167,16 @@ void set_cr0_wp(int wp)
void set_cr4_smep(int smep)
{
unsigned long cr4 = read_cr4();
+ extern u64 ptl2[];
+ if (smep)
+ ptl2[2] &= ~PT_USER_MASK;
cr4 &= ~CR4_SMEP_MASK;
if (smep)
cr4 |= CR4_SMEP_MASK;
write_cr4(cr4);
+ if (!smep)
+ ptl2[2] |= PT_USER_MASK;
}
void set_cr4_pke(int pke)
@@ -859,7 +864,6 @@ static int check_smep_andnot_wp(ac_pool_t *pool)
{
ac_test_t at1;
int err_prepare_andnot_wp, err_smep_andnot_wp;
- extern u64 ptl2[];
ac_test_init(&at1, (void *)(0x123406001000));
@@ -873,7 +877,6 @@ static int check_smep_andnot_wp(ac_pool_t *pool)
at1.flags[AC_CPU_CR0_WP] = 0;
at1.flags[AC_ACCESS_WRITE] = 1;
ac_test_setup_pte(&at1, pool);
- ptl2[2] -= 0x4;
/*
* Here we write the ro user page when
@@ -893,7 +896,6 @@ static int check_smep_andnot_wp(ac_pool_t *pool)
clean_up:
set_cr4_smep(0);
- ptl2[2] += 0x4;
if (!err_prepare_andnot_wp)
goto err;
@@ -933,26 +935,17 @@ int ac_test_run(void)
ac_test_t at;
ac_pool_t pool;
int i, tests, successes;
- extern u64 ptl2[];
printf("run\n");
tests = successes = 0;
ac_env_int(&pool);
ac_test_init(&at, (void *)(0x123400000000 + 16 * smp_id()));
do {
- if (at.flags[AC_CPU_CR4_SMEP] && (ptl2[2] & 0x4))
- ptl2[2] -= 0x4;
- if (!at.flags[AC_CPU_CR4_SMEP] && !(ptl2[2] & 0x4)) {
- set_cr4_smep(0);
- ptl2[2] += 0x4;
- }
-
++tests;
successes += ac_test_exec(&at, &pool);
} while (ac_test_bump(&at));
set_cr4_smep(0);
- ptl2[2] += 0x4;
for (i = 0; i < ARRAY_SIZE(ac_test_cases); i++) {
++tests;
--
2.5.0
--
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