[ARM] 3664/1: crunch: add signal frame save/restore

Patch from Lennert Buytenhek

This patch makes the kernel save Crunch state in userland signal frames,
so that any userland signal handler can safely use the Crunch coprocessor
without corrupting the Crunch state of the code it preempted.

Signed-off-by: Lennert Buytenhek <[e-mail]>
Signed-off-by: Russell King <[e-mail]>

arch/arm/kernel/signal.c

···
 	return ret;
 }
 
+#ifdef CONFIG_CRUNCH
+static int preserve_crunch_context(struct crunch_sigframe *frame)
+{
+	char kbuf[sizeof(*frame) + 8];
+	struct crunch_sigframe *kframe;
+
+	/* the crunch context must be 64 bit aligned */
+	kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+	kframe->magic = CRUNCH_MAGIC;
+	kframe->size = CRUNCH_STORAGE_SIZE;
+	crunch_task_copy(current_thread_info(), &kframe->storage);
+	return __copy_to_user(frame, kframe, sizeof(*frame));
+}
+
+static int restore_crunch_context(struct crunch_sigframe *frame)
+{
+	char kbuf[sizeof(*frame) + 8];
+	struct crunch_sigframe *kframe;
+
+	/* the crunch context must be 64 bit aligned */
+	kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+	if (__copy_from_user(kframe, frame, sizeof(*frame)))
+		return -1;
+	if (kframe->magic != CRUNCH_MAGIC ||
+	    kframe->size != CRUNCH_STORAGE_SIZE)
+		return -1;
+	crunch_task_restore(current_thread_info(), &kframe->storage);
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_IWMMXT
 
 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
···
 	err |= !valid_user_regs(regs);
 
 	aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
+#ifdef CONFIG_CRUNCH
+	if (err == 0)
+		err |= restore_crunch_context(&aux->crunch);
+#endif
 #ifdef CONFIG_IWMMXT
 	if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 		err |= restore_iwmmxt_context(&aux->iwmmxt);
···
 	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 
 	aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
+#ifdef CONFIG_CRUNCH
+	if (err == 0)
+		err |= preserve_crunch_context(&aux->crunch);
+#endif
 #ifdef CONFIG_IWMMXT
 	if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 		err |= preserve_iwmmxt_context(&aux->iwmmxt);

include/asm-arm/ucontext.h

···
  * bytes, to prevent unpredictable padding in the signal frame.
  */
 
+#ifdef CONFIG_CRUNCH
+#define CRUNCH_MAGIC		0x5065cf03
+#define CRUNCH_STORAGE_SIZE	(CRUNCH_SIZE + 8)
+
+struct crunch_sigframe {
+	unsigned long	magic;
+	unsigned long	size;
+	struct crunch_state	storage;
+} __attribute__((__aligned__(8)));
+#endif
+
 #ifdef CONFIG_IWMMXT
 /* iwmmxt_area is 0x98 bytes long, preceeded by 8 bytes of signature */
 #define IWMMXT_MAGIC		0x12ef842a
···
  * one of these.
  */
 struct aux_sigframe {
+#ifdef CONFIG_CRUNCH
+	struct crunch_sigframe	crunch;
+#endif
 #ifdef CONFIG_IWMMXT
 	struct iwmmxt_sigframe	iwmmxt;
 #endif