1/* windows.c: Routines to deal with register window management
2 *            at the C-code level.
3 *
4 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
5 */
6
7#include <linux/kernel.h>
8#include <linux/sched.h>
9#include <linux/string.h>
10#include <linux/mm.h>
11#include <linux/smp.h>
12
13#include <asm/uaccess.h>
14
15/* Do save's until all user register windows are out of the cpu. */
16void flush_user_windows(void)
17{
18	register int ctr asm("g5");
19
20	ctr = 0;
21	__asm__ __volatile__(
22		"\n1:\n\t"
23		"ld	[%%g6 + %2], %%g4\n\t"
24		"orcc	%%g0, %%g4, %%g0\n\t"
25		"add	%0, 1, %0\n\t"
26		"bne	1b\n\t"
27		" save	%%sp, -64, %%sp\n"
28		"2:\n\t"
29		"subcc	%0, 1, %0\n\t"
30		"bne	2b\n\t"
31		" restore %%g0, %%g0, %%g0\n"
32	: "=&r" (ctr)
33	: "0" (ctr),
34	  "i" ((const unsigned long)TI_UWINMASK)
35	: "g4", "cc");
36}
37
38static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *tp)
39{
40	int i;
41
42	for(i = first_win; i < last_win; i++) {
43		tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];
44		memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window32));
45	}
46}
47
48/* Place as many of the user's current register windows
49 * on the stack that we can.  Even if the %sp is unaligned
50 * we still copy the window there, the only case that we don't
51 * succeed is if the %sp points to a bum mapping altogether.
52 * setup_frame() and do_sigreturn() use this before shifting
53 * the user stack around.  Future instruction and hardware
54 * bug workaround routines will need this functionality as
55 * well.
56 */
57void synchronize_user_stack(void)
58{
59	struct thread_info *tp = current_thread_info();
60	int window;
61
62	flush_user_windows();
63	if(!tp->w_saved)
64		return;
65
66	/* Ok, there is some dirty work to do. */
67	for(window = tp->w_saved - 1; window >= 0; window--) {
68		unsigned long sp = tp->rwbuf_stkptrs[window];
69
70		/* Ok, let it rip. */
71		if (copy_to_user((char __user *) sp, &tp->reg_window[window],
72				 sizeof(struct reg_window32)))
73			continue;
74
75		shift_window_buffer(window, tp->w_saved - 1, tp);
76		tp->w_saved--;
77	}
78}
79
80#if 0
81/* An optimization. */
82static inline void copy_aligned_window(void *dest, const void *src)
83{
84	__asm__ __volatile__("ldd [%1], %%g2\n\t"
85			     "ldd [%1 + 0x8], %%g4\n\t"
86			     "std %%g2, [%0]\n\t"
87			     "std %%g4, [%0 + 0x8]\n\t"
88			     "ldd [%1 + 0x10], %%g2\n\t"
89			     "ldd [%1 + 0x18], %%g4\n\t"
90			     "std %%g2, [%0 + 0x10]\n\t"
91			     "std %%g4, [%0 + 0x18]\n\t"
92			     "ldd [%1 + 0x20], %%g2\n\t"
93			     "ldd [%1 + 0x28], %%g4\n\t"
94			     "std %%g2, [%0 + 0x20]\n\t"
95			     "std %%g4, [%0 + 0x28]\n\t"
96			     "ldd [%1 + 0x30], %%g2\n\t"
97			     "ldd [%1 + 0x38], %%g4\n\t"
98			     "std %%g2, [%0 + 0x30]\n\t"
99			     "std %%g4, [%0 + 0x38]\n\t" : :
100			     "r" (dest), "r" (src) :
101			     "g2", "g3", "g4", "g5");
102}
103#endif
104
105/* Try to push the windows in a threads window buffer to the
106 * user stack.  Unaligned %sp's are not allowed here.
107 */
108
109void try_to_clear_window_buffer(struct pt_regs *regs, int who)
110{
111	struct thread_info *tp = current_thread_info();
112	int window;
113
114	flush_user_windows();
115	for(window = 0; window < tp->w_saved; window++) {
116		unsigned long sp = tp->rwbuf_stkptrs[window];
117
118		if ((sp & 7) ||
119		    copy_to_user((char __user *) sp, &tp->reg_window[window],
120				 sizeof(struct reg_window32)))
121			do_exit(SIGILL);
122	}
123	tp->w_saved = 0;
124}
125