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

buffers.c (2745B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/console.h>
      3#include <linux/types.h>
      4#include <linux/wait.h>
      5
      6#include "speakup.h"
      7#include "spk_priv.h"
      8
      9#define SYNTH_BUF_SIZE 8192	/* currently 8K bytes */
     10
     11static u16 synth_buffer[SYNTH_BUF_SIZE];	/* guess what this is for! */
     12static u16 *buff_in = synth_buffer;
     13static u16 *buff_out = synth_buffer;
     14static u16 *buffer_end = synth_buffer + SYNTH_BUF_SIZE - 1;
     15
     16/* These try to throttle applications by stopping the TTYs
     17 * Note: we need to make sure that we will restart them eventually, which is
     18 * usually not possible to do from the notifiers. TODO: it should be possible
     19 * starting from linux 2.6.26.
     20 *
     21 * So we only stop when we know alive == 1 (else we discard the data anyway),
     22 * and the alive synth will eventually call start_ttys from the thread context.
     23 */
     24void speakup_start_ttys(void)
     25{
     26	int i;
     27
     28	for (i = 0; i < MAX_NR_CONSOLES; i++) {
     29		if (speakup_console[i] && speakup_console[i]->tty_stopped)
     30			continue;
     31		if (vc_cons[i].d && vc_cons[i].d->port.tty)
     32			start_tty(vc_cons[i].d->port.tty);
     33	}
     34}
     35EXPORT_SYMBOL_GPL(speakup_start_ttys);
     36
     37static void speakup_stop_ttys(void)
     38{
     39	int i;
     40
     41	for (i = 0; i < MAX_NR_CONSOLES; i++)
     42		if (vc_cons[i].d && vc_cons[i].d->port.tty)
     43			stop_tty(vc_cons[i].d->port.tty);
     44}
     45
     46static int synth_buffer_free(void)
     47{
     48	int chars_free;
     49
     50	if (buff_in >= buff_out)
     51		chars_free = SYNTH_BUF_SIZE - (buff_in - buff_out);
     52	else
     53		chars_free = buff_out - buff_in;
     54	return chars_free;
     55}
     56
     57int synth_buffer_empty(void)
     58{
     59	return (buff_in == buff_out);
     60}
     61EXPORT_SYMBOL_GPL(synth_buffer_empty);
     62
     63void synth_buffer_add(u16 ch)
     64{
     65	if (!synth->alive) {
     66		/* This makes sure that we won't stop TTYs if there is no synth
     67		 * to restart them
     68		 */
     69		return;
     70	}
     71	if (synth_buffer_free() <= 100) {
     72		synth_start();
     73		speakup_stop_ttys();
     74	}
     75	if (synth_buffer_free() <= 1)
     76		return;
     77	*buff_in++ = ch;
     78	if (buff_in > buffer_end)
     79		buff_in = synth_buffer;
     80	/* We have written something to the speech synthesis, so we are not
     81	 * paused any more.
     82	 */
     83	spk_paused = false;
     84}
     85
     86u16 synth_buffer_getc(void)
     87{
     88	u16 ch;
     89
     90	if (buff_out == buff_in)
     91		return 0;
     92	ch = *buff_out++;
     93	if (buff_out > buffer_end)
     94		buff_out = synth_buffer;
     95	return ch;
     96}
     97EXPORT_SYMBOL_GPL(synth_buffer_getc);
     98
     99u16 synth_buffer_peek(void)
    100{
    101	if (buff_out == buff_in)
    102		return 0;
    103	return *buff_out;
    104}
    105EXPORT_SYMBOL_GPL(synth_buffer_peek);
    106
    107void synth_buffer_skip_nonlatin1(void)
    108{
    109	while (buff_out != buff_in) {
    110		if (*buff_out < 0x100)
    111			return;
    112		buff_out++;
    113		if (buff_out > buffer_end)
    114			buff_out = synth_buffer;
    115	}
    116}
    117EXPORT_SYMBOL_GPL(synth_buffer_skip_nonlatin1);
    118
    119void synth_buffer_clear(void)
    120{
    121	buff_in = synth_buffer;
    122	buff_out = synth_buffer;
    123}
    124EXPORT_SYMBOL_GPL(synth_buffer_clear);