cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

windows.c (3407B)

      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}