powerpc: Fix bug causing FP registers corruption on UP + preempt
This fixes a bug noticed by Paolo Galtieri and fixed for ARCH=ppc in
the previous commit (ppc: fix floating point register corruption).
This fixes the arch/powerpc code by adding preempt_disable/enable,
and also cleans it up a bit by pulling out the code that discards
any lazily-switched CPU register state into a new function, rather
than having that code repeated in three places.
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index a5a7542..105d560 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -201,6 +201,28 @@
}
#endif /* CONFIG_SPE */
+/*
+ * If we are doing lazy switching of CPU state (FP, altivec or SPE),
+ * and the current task has some state, discard it.
+ */
+static inline void discard_lazy_cpu_state(void)
+{
+#ifndef CONFIG_SMP
+ preempt_disable();
+ if (last_task_used_math == current)
+ last_task_used_math = NULL;
+#ifdef CONFIG_ALTIVEC
+ if (last_task_used_altivec == current)
+ last_task_used_altivec = NULL;
+#endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_SPE
+ if (last_task_used_spe == current)
+ last_task_used_spe = NULL;
+#endif
+ preempt_enable();
+#endif /* CONFIG_SMP */
+}
+
int set_dabr(unsigned long dabr)
{
if (ppc_md.set_dabr)
@@ -434,19 +456,7 @@
void exit_thread(void)
{
kprobe_flush_task(current);
-
-#ifndef CONFIG_SMP
- if (last_task_used_math == current)
- last_task_used_math = NULL;
-#ifdef CONFIG_ALTIVEC
- if (last_task_used_altivec == current)
- last_task_used_altivec = NULL;
-#endif /* CONFIG_ALTIVEC */
-#ifdef CONFIG_SPE
- if (last_task_used_spe == current)
- last_task_used_spe = NULL;
-#endif
-#endif /* CONFIG_SMP */
+ discard_lazy_cpu_state();
}
void flush_thread(void)
@@ -458,18 +468,7 @@
t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
#endif
-#ifndef CONFIG_SMP
- if (last_task_used_math == current)
- last_task_used_math = NULL;
-#ifdef CONFIG_ALTIVEC
- if (last_task_used_altivec == current)
- last_task_used_altivec = NULL;
-#endif /* CONFIG_ALTIVEC */
-#ifdef CONFIG_SPE
- if (last_task_used_spe == current)
- last_task_used_spe = NULL;
-#endif
-#endif /* CONFIG_SMP */
+ discard_lazy_cpu_state();
#ifdef CONFIG_PPC64 /* for now */
if (current->thread.dabr) {
@@ -635,18 +634,7 @@
}
#endif
-#ifndef CONFIG_SMP
- if (last_task_used_math == current)
- last_task_used_math = NULL;
-#ifdef CONFIG_ALTIVEC
- if (last_task_used_altivec == current)
- last_task_used_altivec = NULL;
-#endif
-#ifdef CONFIG_SPE
- if (last_task_used_spe == current)
- last_task_used_spe = NULL;
-#endif
-#endif /* CONFIG_SMP */
+ discard_lazy_cpu_state();
memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
current->thread.fpscr.val = 0;
#ifdef CONFIG_ALTIVEC