summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/cpu/bugs.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
-rw-r--r--arch/x86/kernel/cpu/bugs.c92
1 files changed, 54 insertions, 38 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index b6f887be440c..0b71970d2d3d 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -588,7 +588,9 @@ early_param("nospectre_v1", nospectre_v1_cmdline);
static enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init =
SPECTRE_V2_NONE;
-static enum spectre_v2_user_mitigation spectre_v2_user __ro_after_init =
+static enum spectre_v2_user_mitigation spectre_v2_user_stibp __ro_after_init =
+ SPECTRE_V2_USER_NONE;
+static enum spectre_v2_user_mitigation spectre_v2_user_ibpb __ro_after_init =
SPECTRE_V2_USER_NONE;
#ifdef CONFIG_RETPOLINE
@@ -734,15 +736,6 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
break;
}
- /*
- * At this point, an STIBP mode other than "off" has been set.
- * If STIBP support is not being forced, check if STIBP always-on
- * is preferred.
- */
- if (mode != SPECTRE_V2_USER_STRICT &&
- boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
- mode = SPECTRE_V2_USER_STRICT_PREFERRED;
-
/* Initialize Indirect Branch Prediction Barrier */
if (boot_cpu_has(X86_FEATURE_IBPB)) {
setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
@@ -765,23 +758,36 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
pr_info("mitigation: Enabling %s Indirect Branch Prediction Barrier\n",
static_key_enabled(&switch_mm_always_ibpb) ?
"always-on" : "conditional");
+
+ spectre_v2_user_ibpb = mode;
}
- /* If enhanced IBRS is enabled no STIBP required */
- if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
+ /*
+ * If enhanced IBRS is enabled or SMT impossible, STIBP is not
+ * required.
+ */
+ if (!smt_possible || spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
return;
/*
- * If SMT is not possible or STIBP is not available clear the STIBP
- * mode.
+ * At this point, an STIBP mode other than "off" has been set.
+ * If STIBP support is not being forced, check if STIBP always-on
+ * is preferred.
*/
- if (!smt_possible || !boot_cpu_has(X86_FEATURE_STIBP))
+ if (mode != SPECTRE_V2_USER_STRICT &&
+ boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
+ mode = SPECTRE_V2_USER_STRICT_PREFERRED;
+
+ /*
+ * If STIBP is not available, clear the STIBP mode.
+ */
+ if (!boot_cpu_has(X86_FEATURE_STIBP))
mode = SPECTRE_V2_USER_NONE;
+
+ spectre_v2_user_stibp = mode;
+
set_mode:
- spectre_v2_user = mode;
- /* Only print the STIBP mode when SMT possible */
- if (smt_possible)
- pr_info("%s\n", spectre_v2_user_strings[mode]);
+ pr_info("%s\n", spectre_v2_user_strings[mode]);
}
static const char * const spectre_v2_strings[] = {
@@ -1014,7 +1020,7 @@ void cpu_bugs_smt_update(void)
{
mutex_lock(&spec_ctrl_mutex);
- switch (spectre_v2_user) {
+ switch (spectre_v2_user_stibp) {
case SPECTRE_V2_USER_NONE:
break;
case SPECTRE_V2_USER_STRICT:
@@ -1257,14 +1263,19 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
{
switch (ctrl) {
case PR_SPEC_ENABLE:
- if (spectre_v2_user == SPECTRE_V2_USER_NONE)
+ if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
+ spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
return 0;
/*
* Indirect branch speculation is always disabled in strict
- * mode.
+ * mode. It can neither be enabled if it was force-disabled
+ * by a previous prctl call.
+
*/
- if (spectre_v2_user == SPECTRE_V2_USER_STRICT ||
- spectre_v2_user == SPECTRE_V2_USER_STRICT_PREFERRED)
+ if (spectre_v2_user_ibpb == SPECTRE_V2_USER_STRICT ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED ||
+ task_spec_ib_force_disable(task))
return -EPERM;
task_clear_spec_ib_disable(task);
task_update_spec_tif(task);
@@ -1275,10 +1286,12 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
* Indirect branch speculation is always allowed when
* mitigation is force disabled.
*/
- if (spectre_v2_user == SPECTRE_V2_USER_NONE)
+ if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
+ spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
return -EPERM;
- if (spectre_v2_user == SPECTRE_V2_USER_STRICT ||
- spectre_v2_user == SPECTRE_V2_USER_STRICT_PREFERRED)
+ if (spectre_v2_user_ibpb == SPECTRE_V2_USER_STRICT ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED)
return 0;
task_set_spec_ib_disable(task);
if (ctrl == PR_SPEC_FORCE_DISABLE)
@@ -1309,7 +1322,8 @@ void arch_seccomp_spec_mitigate(struct task_struct *task)
{
if (ssb_mode == SPEC_STORE_BYPASS_SECCOMP)
ssb_prctl_set(task, PR_SPEC_FORCE_DISABLE);
- if (spectre_v2_user == SPECTRE_V2_USER_SECCOMP)
+ if (spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP)
ib_prctl_set(task, PR_SPEC_FORCE_DISABLE);
}
#endif
@@ -1340,22 +1354,24 @@ static int ib_prctl_get(struct task_struct *task)
if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
return PR_SPEC_NOT_AFFECTED;
- switch (spectre_v2_user) {
- case SPECTRE_V2_USER_NONE:
+ if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
+ spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
return PR_SPEC_ENABLE;
- case SPECTRE_V2_USER_PRCTL:
- case SPECTRE_V2_USER_SECCOMP:
+ else if (spectre_v2_user_ibpb == SPECTRE_V2_USER_STRICT ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED)
+ return PR_SPEC_DISABLE;
+ else if (spectre_v2_user_ibpb == SPECTRE_V2_USER_PRCTL ||
+ spectre_v2_user_ibpb == SPECTRE_V2_USER_SECCOMP ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_PRCTL ||
+ spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP) {
if (task_spec_ib_force_disable(task))
return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE;
if (task_spec_ib_disable(task))
return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
- case SPECTRE_V2_USER_STRICT:
- case SPECTRE_V2_USER_STRICT_PREFERRED:
- return PR_SPEC_DISABLE;
- default:
+ } else
return PR_SPEC_NOT_AFFECTED;
- }
}
int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
@@ -1594,7 +1610,7 @@ static char *stibp_state(void)
if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
return "";
- switch (spectre_v2_user) {
+ switch (spectre_v2_user_stibp) {
case SPECTRE_V2_USER_NONE:
return ", STIBP: disabled";
case SPECTRE_V2_USER_STRICT:
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-10 13:31:22 +0000