ARM: 7399/1: vfp: move user vfp state save/restore code out of signal.c

The user VFP state must be preserved (subject to ucontext modifications)
across invocation of a signal handler and this is currently handled by
vfp_{preserve,restore}_context in signal.c

Since this code requires intimate low-level knowledge of the VFP state,
this patch moves it into vfpmodule.c.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 90 insertions, 51 deletions

diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index d4c24d412a8d..0f04d84582e1 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -118,6 +118,13 @@ extern void iwmmxt_task_switch(struct thread_info *);
 extern void vfp_sync_hwstate(struct thread_info *);
 extern void vfp_flush_hwstate(struct thread_info *);
 
+struct user_vfp;
+struct user_vfp_exc;
+
+extern int vfp_preserve_user_clear_hwstate(struct user_vfp __user *,
+                                           struct user_vfp_exc __user *);
+extern int vfp_restore_user_hwstate(struct user_vfp __user *,
+                                    struct user_vfp_exc __user *);
 #endif
 
 /*
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 7cb532fc8aa4..d68d1b694680 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -180,44 +180,23 @@ static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
 
 static int preserve_vfp_context(struct vfp_sigframe __user *frame)
 {
-        struct thread_info *thread = current_thread_info();
-        struct vfp_hard_struct *h = &thread->vfpstate.hard;
         const unsigned long magic = VFP_MAGIC;
         const unsigned long size = VFP_STORAGE_SIZE;
         int err = 0;
 
-        vfp_sync_hwstate(thread);
         __put_user_error(magic, &frame->magic, err);
         __put_user_error(size, &frame->size, err);
 
-        /*
-         * Copy the floating point registers. There can be unused
-         * registers see asm/hwcap.h for details.
-         */
-        err |= __copy_to_user(&frame->ufp.fpregs, &h->fpregs,
-                              sizeof(h->fpregs));
-        /*
-         * Copy the status and control register.
-         */
-        __put_user_error(h->fpscr, &frame->ufp.fpscr, err);
-
-        /*
-         * Copy the exception registers.
-         */
-        __put_user_error(h->fpexc, &frame->ufp_exc.fpexc, err);
-        __put_user_error(h->fpinst, &frame->ufp_exc.fpinst, err);
-        __put_user_error(h->fpinst2, &frame->ufp_exc.fpinst2, err);
+        if (err)
+                return -EFAULT;
 
-        return err ? -EFAULT : 0;
+        return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc);
 }
 
 static int restore_vfp_context(struct vfp_sigframe __user *frame)
 {
-        struct thread_info *thread = current_thread_info();
-        struct vfp_hard_struct *h = &thread->vfpstate.hard;
         unsigned long magic;
         unsigned long size;
-        unsigned long fpexc;
         int err = 0;
 
         __get_user_error(magic, &frame->magic, err);
@@ -228,33 +207,7 @@ static int restore_vfp_context(struct vfp_sigframe __user *frame)
         if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
                 return -EINVAL;
 
-        vfp_flush_hwstate(thread);
-
-        /*
-         * Copy the floating point registers. There can be unused
-         * registers see asm/hwcap.h for details.
-         */
-        err |= __copy_from_user(&h->fpregs, &frame->ufp.fpregs,
-                                sizeof(h->fpregs));
-        /*
-         * Copy the status and control register.
-         */
-        __get_user_error(h->fpscr, &frame->ufp.fpscr, err);
-
-        /*
-         * Sanitise and restore the exception registers.
-         */
-        __get_user_error(fpexc, &frame->ufp_exc.fpexc, err);
-        /* Ensure the VFP is enabled. */
-        fpexc |= FPEXC_EN;
-        /* Ensure FPINST2 is invalid and the exception flag is cleared. */
-        fpexc &= ~(FPEXC_EX | FPEXC_FP2V);
-        h->fpexc = fpexc;
-
-        __get_user_error(h->fpinst, &frame->ufp_exc.fpinst, err);
-        __get_user_error(h->fpinst2, &frame->ufp_exc.fpinst2, err);
-
-        return err ? -EFAULT : 0;
+        return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc);
 }
 
 #endif
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index 858748eaa144..05872d92fca2 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -17,6 +17,8 @@
 #include <linux/sched.h>
 #include <linux/smp.h>
 #include <linux/init.h>
+#include <linux/uaccess.h>
+#include <linux/user.h>
 
 #include <asm/cp15.h>
 #include <asm/cputype.h>
@@ -529,6 +531,83 @@ void vfp_flush_hwstate(struct thread_info *thread)
 }
 
 /*
+ * Save the current VFP state into the provided structures and prepare
+ * for entry into a new function (signal handler).
+ */
+int vfp_preserve_user_clear_hwstate(struct user_vfp __user *ufp,
+                                    struct user_vfp_exc __user *ufp_exc)
+{
+        struct thread_info *thread = current_thread_info();
+        struct vfp_hard_struct *hwstate = &thread->vfpstate.hard;
+        int err = 0;
+
+        /* Ensure that the saved hwstate is up-to-date. */
+        vfp_sync_hwstate(thread);
+
+        /*
+         * Copy the floating point registers. There can be unused
+         * registers see asm/hwcap.h for details.
+         */
+        err |= __copy_to_user(&ufp->fpregs, &hwstate->fpregs,
+                              sizeof(hwstate->fpregs));
+        /*
+         * Copy the status and control register.
+         */
+        __put_user_error(hwstate->fpscr, &ufp->fpscr, err);
+
+        /*
+         * Copy the exception registers.
+         */
+        __put_user_error(hwstate->fpexc, &ufp_exc->fpexc, err);
+        __put_user_error(hwstate->fpinst, &ufp_exc->fpinst, err);
+        __put_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err);
+
+        if (err)
+                return -EFAULT;
+        return 0;
+}
+
+/* Sanitise and restore the current VFP state from the provided structures. */
+int vfp_restore_user_hwstate(struct user_vfp __user *ufp,
+                             struct user_vfp_exc __user *ufp_exc)
+{
+        struct thread_info *thread = current_thread_info();
+        struct vfp_hard_struct *hwstate = &thread->vfpstate.hard;
+        unsigned long fpexc;
+        int err = 0;
+
+        vfp_flush_hwstate(thread);
+
+        /*
+         * Copy the floating point registers. There can be unused
+         * registers see asm/hwcap.h for details.
+         */
+        err |= __copy_from_user(&hwstate->fpregs, &ufp->fpregs,
+                                sizeof(hwstate->fpregs));
+        /*
+         * Copy the status and control register.
+         */
+        __get_user_error(hwstate->fpscr, &ufp->fpscr, err);
+
+        /*
+         * Sanitise and restore the exception registers.
+         */
+        __get_user_error(fpexc, &ufp_exc->fpexc, err);
+
+        /* Ensure the VFP is enabled. */
+        fpexc |= FPEXC_EN;
+
+        /* Ensure FPINST2 is invalid and the exception flag is cleared. */
+        fpexc &= ~(FPEXC_EX | FPEXC_FP2V);
+        hwstate->fpexc = fpexc;
+
+        __get_user_error(hwstate->fpinst, &ufp_exc->fpinst, err);
+        __get_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err);
+
+        return err ? -EFAULT : 0;
+}
+
+/*
  * VFP hardware can lose all context when a CPU goes offline.
  * As we will be running in SMP mode with CPU hotplug, we will save the
  * hardware state at every thread switch.  We clear our held state when