File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/arch/sparc/kernel/windows.c b/arch/sparc/kernel/windows.c
new file mode 100644
index 0000000..87bab0a
--- /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;
+}