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// SPDX-License-Identifier: GPL-2.0
/* 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 <linux/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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