3 files changed, 49 insertions, 4 deletions
diff --git a/arch/arm/vfp/vfp.h b/arch/arm/vfp/vfp.h
index 8de86e4fead..c8c98dd44ad 100644
--- a/arch/arm/vfp/vfp.h
+++ b/arch/arm/vfp/vfp.h
@@ -377,6 +377,4 @@ struct op {
 	u32 flags;
 };
 
-#if defined(CONFIG_SMP) || defined(CONFIG_PM)
 extern void vfp_save_state(void *location, u32 fpexc);
-#endif
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index c92a08bd6a8..a5a4e57763c 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -172,7 +172,6 @@ process_exception:
 					@ retry the faulted instruction
 ENDPROC(vfp_support_entry)
 
-#if defined(CONFIG_SMP) || defined(CONFIG_PM)
 ENTRY(vfp_save_state)
 	@ Save the current VFP state
 	@ r0 - save location
@@ -190,7 +189,6 @@ ENTRY(vfp_save_state)
 	stmia	r0, {r1, r2, r3, r12}	@ save FPEXC, FPSCR, FPINST, FPINST2
 	mov	pc, lr
 ENDPROC(vfp_save_state)
-#endif
 
 last_VFP_context_address:
 	.word	last_VFP_context
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 9f476a1be2c..7e1239041b3 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -377,6 +377,55 @@ static void vfp_pm_init(void)
 static inline void vfp_pm_init(void) { }
 #endif /* CONFIG_PM */
 
+/*
+ * Synchronise the hardware VFP state of a thread other than current with the
+ * saved one. This function is used by the ptrace mechanism.
+ */
+#ifdef CONFIG_SMP
+void vfp_sync_state(struct thread_info *thread)
+{
+	/*
+	 * On SMP systems, the VFP state is automatically saved at every
+	 * context switch. We mark the thread VFP state as belonging to a
+	 * non-existent CPU so that the saved one will be reloaded when
+	 * needed.
+	 */
+	thread->vfpstate.hard.cpu = NR_CPUS;
+}
+#else
+void vfp_sync_state(struct thread_info *thread)
+{
+	unsigned int cpu = get_cpu();
+	u32 fpexc = fmrx(FPEXC);
+
+	/*
+	 * If VFP is enabled, the previous state was already saved and
+	 * last_VFP_context updated.
+	 */
+	if (fpexc & FPEXC_EN)
+		goto out;
+
+	if (!last_VFP_context[cpu])
+		goto out;
+
+	/*
+	 * Save the last VFP state on this CPU.
+	 */
+	fmxr(FPEXC, fpexc | FPEXC_EN);
+	vfp_save_state(last_VFP_context[cpu], fpexc);
+	fmxr(FPEXC, fpexc);
+
+	/*
+	 * Set the context to NULL to force a reload the next time the thread
+	 * uses the VFP.
+	 */
+	last_VFP_context[cpu] = NULL;
+
+out:
+	put_cpu();
+}
+#endif
+
 #include <linux/smp.h>
 
 /*