1// SPDX-License-Identifier: GPL-2.0
2/* windows.c: Routines to deal with register window management
3 *            at the C-code level.
4 *
5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
6 */
7
8#include <linux/kernel.h>
9#include <linux/sched.h>
10#include <linux/string.h>
11#include <linux/mm.h>
12#include <linux/smp.h>
13
14#include <asm/cacheflush.h>
15#include <linux/uaccess.h>
16
17#include "kernel.h"
18
19/* Do save's until all user register windows are out of the cpu. */
20void flush_user_windows(void)
21{
22	register int ctr asm("g5");
23
24	ctr = 0;
25	__asm__ __volatile__(
26		"\n1:\n\t"
27		"ld	[%%g6 + %2], %%g4\n\t"
28		"orcc	%%g0, %%g4, %%g0\n\t"
29		"add	%0, 1, %0\n\t"
30		"bne	1b\n\t"
31		" save	%%sp, -64, %%sp\n"
32		"2:\n\t"
33		"subcc	%0, 1, %0\n\t"
34		"bne	2b\n\t"
35		" restore %%g0, %%g0, %%g0\n"
36	: "=&r" (ctr)
37	: "0" (ctr),
38	  "i" ((const unsigned long)TI_UWINMASK)
39	: "g4", "cc");
40}
41
42static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *tp)
43{
44	int i;
45
46	for(i = first_win; i < last_win; i++) {
47		tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1];
48		memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window32));
49	}
50}
51
52/* Place as many of the user's current register windows
53 * on the stack that we can.  Even if the %sp is unaligned
54 * we still copy the window there, the only case that we don't
55 * succeed is if the %sp points to a bum mapping altogether.
56 * setup_frame() and do_sigreturn() use this before shifting
57 * the user stack around.  Future instruction and hardware
58 * bug workaround routines will need this functionality as
59 * well.
60 */
61void synchronize_user_stack(void)
62{
63	struct thread_info *tp = current_thread_info();
64	int window;
65
66	flush_user_windows();
67	if(!tp->w_saved)
68		return;
69
70	/* Ok, there is some dirty work to do. */
71	for(window = tp->w_saved - 1; window >= 0; window--) {
72		unsigned long sp = tp->rwbuf_stkptrs[window];
73
74		/* Ok, let it rip. */
75		if (copy_to_user((char __user *) sp, &tp->reg_window[window],
76				 sizeof(struct reg_window32)))
77			continue;
78
79		shift_window_buffer(window, tp->w_saved - 1, tp);
80		tp->w_saved--;
81	}
82}
83
84#if 0
85/* An optimization. */
86static inline void copy_aligned_window(void *dest, const void *src)
87{
88	__asm__ __volatile__("ldd [%1], %%g2\n\t"
89			     "ldd [%1 + 0x8], %%g4\n\t"
90			     "std %%g2, [%0]\n\t"
91			     "std %%g4, [%0 + 0x8]\n\t"
92			     "ldd [%1 + 0x10], %%g2\n\t"
93			     "ldd [%1 + 0x18], %%g4\n\t"
94			     "std %%g2, [%0 + 0x10]\n\t"
95			     "std %%g4, [%0 + 0x18]\n\t"
96			     "ldd [%1 + 0x20], %%g2\n\t"
97			     "ldd [%1 + 0x28], %%g4\n\t"
98			     "std %%g2, [%0 + 0x20]\n\t"
99			     "std %%g4, [%0 + 0x28]\n\t"
100			     "ldd [%1 + 0x30], %%g2\n\t"
101			     "ldd [%1 + 0x38], %%g4\n\t"
102			     "std %%g2, [%0 + 0x30]\n\t"
103			     "std %%g4, [%0 + 0x38]\n\t" : :
104			     "r" (dest), "r" (src) :
105			     "g2", "g3", "g4", "g5");
106}
107#endif
108
109/* Try to push the windows in a threads window buffer to the
110 * user stack.  Unaligned %sp's are not allowed here.
111 */
112
113void try_to_clear_window_buffer(struct pt_regs *regs, int who)
114{
115	struct thread_info *tp = current_thread_info();
116	int window;
117
118	flush_user_windows();
119	for(window = 0; window < tp->w_saved; window++) {
120		unsigned long sp = tp->rwbuf_stkptrs[window];
121
122		if ((sp & 7) ||
123		    copy_to_user((char __user *) sp, &tp->reg_window[window],
124				 sizeof(struct reg_window32))) {
125			force_exit_sig(SIGILL);
126			return;
127		}
128	}
129	tp->w_saved = 0;
130}
131