From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/sparc/kernel/windows.c | 127 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 arch/sparc/kernel/windows.c

(limited to 'arch/sparc/kernel/windows.c')

diff --git a/arch/sparc/kernel/windows.c b/arch/sparc/kernel/windows.c
new file mode 100644
index 000000000..87bab0a38
--- /dev/null
+++ b/arch/sparc/kernel/windows.c
@@ -0,0 +1,127 @@
+/* windows.c: Routines to deal with register window management
+ *            at the C-code level.
+ *
+ * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+
+#include <asm/cacheflush.h>
+#include <asm/uaccess.h>
+
+#include "kernel.h"
+
+/* Do save's until all user register windows are out of the cpu. */
+void flush_user_windows(void)
+{
+	register int ctr asm("g5");
+
+	ctr = 0;
+	__asm__ __volatile__(
+		"\n1:\n\t"
+		"ld	[%%g6 + %2], %%g4\n\t"
+		"orcc	%%g0, %%g4, %%g0\n\t"
+		"add	%0, 1, %0\n\t"
+		"bne	1b\n\t"
+		" save	%%sp, -64, %%sp\n"
+		"2:\n\t"
+		"subcc	%0, 1, %0\n\t"
+		"bne	2b\n\t"
+		" restore %%g0, %%g0, %%g0\n"
+	: "=&r" (ctr)
+	: "0" (ctr),
+	  "i" ((const unsigned long)TI_UWINMASK)
+	: "g4", "cc");
+}
+
+static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *tp)
+{
+	int i;
+
+	for(i = first_win; i < last_win; i++) {
+		tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];
+		memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window32));
+	}
+}
+
+/* Place as many of the user's current register windows 
+ * on the stack that we can.  Even if the %sp is unaligned
+ * we still copy the window there, the only case that we don't
+ * succeed is if the %sp points to a bum mapping altogether.
+ * setup_frame() and do_sigreturn() use this before shifting
+ * the user stack around.  Future instruction and hardware
+ * bug workaround routines will need this functionality as
+ * well.
+ */
+void synchronize_user_stack(void)
+{
+	struct thread_info *tp = current_thread_info();
+	int window;
+
+	flush_user_windows();
+	if(!tp->w_saved)
+		return;
+
+	/* Ok, there is some dirty work to do. */
+	for(window = tp->w_saved - 1; window >= 0; window--) {
+		unsigned long sp = tp->rwbuf_stkptrs[window];
+
+		/* Ok, let it rip. */
+		if (copy_to_user((char __user *) sp, &tp->reg_window[window],
+				 sizeof(struct reg_window32)))
+			continue;
+
+		shift_window_buffer(window, tp->w_saved - 1, tp);
+		tp->w_saved--;
+	}
+}
+
+#if 0
+/* An optimization. */
+static inline void copy_aligned_window(void *dest, const void *src)
+{
+	__asm__ __volatile__("ldd [%1], %%g2\n\t"
+			     "ldd [%1 + 0x8], %%g4\n\t"
+			     "std %%g2, [%0]\n\t"
+			     "std %%g4, [%0 + 0x8]\n\t"
+			     "ldd [%1 + 0x10], %%g2\n\t"
+			     "ldd [%1 + 0x18], %%g4\n\t"
+			     "std %%g2, [%0 + 0x10]\n\t"
+			     "std %%g4, [%0 + 0x18]\n\t"
+			     "ldd [%1 + 0x20], %%g2\n\t"
+			     "ldd [%1 + 0x28], %%g4\n\t"
+			     "std %%g2, [%0 + 0x20]\n\t"
+			     "std %%g4, [%0 + 0x28]\n\t"
+			     "ldd [%1 + 0x30], %%g2\n\t"
+			     "ldd [%1 + 0x38], %%g4\n\t"
+			     "std %%g2, [%0 + 0x30]\n\t"
+			     "std %%g4, [%0 + 0x38]\n\t" : :
+			     "r" (dest), "r" (src) :
+			     "g2", "g3", "g4", "g5");
+}
+#endif
+
+/* Try to push the windows in a threads window buffer to the
+ * user stack.  Unaligned %sp's are not allowed here.
+ */
+
+void try_to_clear_window_buffer(struct pt_regs *regs, int who)
+{
+	struct thread_info *tp = current_thread_info();
+	int window;
+
+	flush_user_windows();
+	for(window = 0; window < tp->w_saved; window++) {
+		unsigned long sp = tp->rwbuf_stkptrs[window];
+
+		if ((sp & 7) ||
+		    copy_to_user((char __user *) sp, &tp->reg_window[window],
+				 sizeof(struct reg_window32)))
+			do_exit(SIGILL);
+	}
+	tp->w_saved = 0;
+}
-- 
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