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Diffstat (limited to 'arch/arm64/kernel/fpsimd.c')
-rw-r--r--arch/arm64/kernel/fpsimd.c30
1 files changed, 27 insertions, 3 deletions
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 3eb338f14386..94289d126993 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -269,6 +269,7 @@ static void sve_free(struct task_struct *task)
*/
static void task_fpsimd_load(void)
{
+ WARN_ON(!system_supports_fpsimd());
WARN_ON(!have_cpu_fpsimd_context());
if (system_supports_sve() && test_thread_flag(TIF_SVE))
@@ -289,6 +290,7 @@ static void fpsimd_save(void)
this_cpu_ptr(&fpsimd_last_state);
/* set by fpsimd_bind_task_to_cpu() or fpsimd_bind_state_to_cpu() */
+ WARN_ON(!system_supports_fpsimd());
WARN_ON(!have_cpu_fpsimd_context());
if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {
@@ -1092,6 +1094,7 @@ void fpsimd_bind_task_to_cpu(void)
struct fpsimd_last_state_struct *last =
this_cpu_ptr(&fpsimd_last_state);
+ WARN_ON(!system_supports_fpsimd());
last->st = &current->thread.uw.fpsimd_state;
last->sve_state = current->thread.sve_state;
last->sve_vl = current->thread.sve_vl;
@@ -1114,6 +1117,7 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state,
struct fpsimd_last_state_struct *last =
this_cpu_ptr(&fpsimd_last_state);
+ WARN_ON(!system_supports_fpsimd());
WARN_ON(!in_softirq() && !irqs_disabled());
last->st = st;
@@ -1128,8 +1132,19 @@ void fpsimd_bind_state_to_cpu(struct user_fpsimd_state *st, void *sve_state,
*/
void fpsimd_restore_current_state(void)
{
- if (!system_supports_fpsimd())
+ /*
+ * For the tasks that were created before we detected the absence of
+ * FP/SIMD, the TIF_FOREIGN_FPSTATE could be set via fpsimd_thread_switch(),
+ * e.g, init. This could be then inherited by the children processes.
+ * If we later detect that the system doesn't support FP/SIMD,
+ * we must clear the flag for all the tasks to indicate that the
+ * FPSTATE is clean (as we can't have one) to avoid looping for ever in
+ * do_notify_resume().
+ */
+ if (!system_supports_fpsimd()) {
+ clear_thread_flag(TIF_FOREIGN_FPSTATE);
return;
+ }
get_cpu_fpsimd_context();
@@ -1148,7 +1163,7 @@ void fpsimd_restore_current_state(void)
*/
void fpsimd_update_current_state(struct user_fpsimd_state const *state)
{
- if (!system_supports_fpsimd())
+ if (WARN_ON(!system_supports_fpsimd()))
return;
get_cpu_fpsimd_context();
@@ -1179,7 +1194,13 @@ void fpsimd_update_current_state(struct user_fpsimd_state const *state)
void fpsimd_flush_task_state(struct task_struct *t)
{
t->thread.fpsimd_cpu = NR_CPUS;
-
+ /*
+ * If we don't support fpsimd, bail out after we have
+ * reset the fpsimd_cpu for this task and clear the
+ * FPSTATE.
+ */
+ if (!system_supports_fpsimd())
+ return;
barrier();
set_tsk_thread_flag(t, TIF_FOREIGN_FPSTATE);
@@ -1193,6 +1214,7 @@ void fpsimd_flush_task_state(struct task_struct *t)
*/
static void fpsimd_flush_cpu_state(void)
{
+ WARN_ON(!system_supports_fpsimd());
__this_cpu_write(fpsimd_last_state.st, NULL);
set_thread_flag(TIF_FOREIGN_FPSTATE);
}
@@ -1203,6 +1225,8 @@ static void fpsimd_flush_cpu_state(void)
*/
void fpsimd_save_and_flush_cpu_state(void)
{
+ if (!system_supports_fpsimd())
+ return;
WARN_ON(preemptible());
__get_cpu_fpsimd_context();
fpsimd_save();