[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 <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 39 insertions, 0 deletions

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 1ce05ec086c6..83a8d3c95eb3 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -132,6 +132,37 @@ sys_sigaction(int sig, const struct old_sigaction __user *act,
         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)
@@ -214,6 +245,10 @@ static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
         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);
@@ -333,6 +368,10 @@ setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
         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);