LXR qemu/linux-user/semihost.c

   1/*
   2 * ARM Compatible Semihosting Console Support.
   3 *
   4 * Copyright (c) 2019 Linaro Ltd
   5 *
   6 * Currently ARM and RISC-V are unique in having support for
   7 * semihosting support in linux-user. So for now we implement the
   8 * common console API but just for arm and risc-v linux-user.
   9 *
  10 * SPDX-License-Identifier: GPL-2.0-or-later
  11 */
  12
  13#include "qemu/osdep.h"
  14#include "semihosting/console.h"
  15#include "qemu.h"
  16#include <termios.h>
  17
  18int qemu_semihosting_console_outs(CPUArchState *env, target_ulong addr)
  19{
  20    int len = target_strlen(addr);
  21    void *s;
  22    if (len < 0){
  23       qemu_log_mask(LOG_GUEST_ERROR,
  24                     "%s: passed inaccessible address " TARGET_FMT_lx,
  25                     __func__, addr);
  26       return 0;
  27    }
  28    s = lock_user(VERIFY_READ, addr, (long)(len + 1), 1);
  29    g_assert(s);  /* target_strlen has already verified this will work */
  30    len = write(STDERR_FILENO, s, len);
  31    unlock_user(s, addr, 0);
  32    return len;
  33}
  34
  35void qemu_semihosting_console_outc(CPUArchState *env, target_ulong addr)
  36{
  37    char c;
  38
  39    if (get_user_u8(c, addr)) {
  40        qemu_log_mask(LOG_GUEST_ERROR,
  41                      "%s: passed inaccessible address " TARGET_FMT_lx,
  42                      __func__, addr);
  43    } else {
  44        if (write(STDERR_FILENO, &c, 1) != 1) {
  45            qemu_log_mask(LOG_UNIMP, "%s: unexpected write to stdout failure",
  46                          __func__);
  47        }
  48    }
  49}
  50
  51/*
  52 * For linux-user we can safely block. However as we want to return as
  53 * soon as a character is read we need to tweak the termio to disable
  54 * line buffering. We restore the old mode afterwards in case the
  55 * program is expecting more normal behaviour. This is slow but
  56 * nothing using semihosting console reading is expecting to be fast.
  57 */
  58target_ulong qemu_semihosting_console_inc(CPUArchState *env)
  59{
  60    uint8_t c;
  61    struct termios old_tio, new_tio;
  62
  63    /* Disable line-buffering and echo */
  64    tcgetattr(STDIN_FILENO, &old_tio);
  65    new_tio = old_tio;
  66    new_tio.c_lflag &= (~ICANON & ~ECHO);
  67    tcsetattr(STDIN_FILENO, TCSANOW, &new_tio);
  68
  69    c = getchar();
  70
  71    /* restore config */
  72    tcsetattr(STDIN_FILENO, TCSANOW, &old_tio);
  73
  74    return (target_ulong) c;
  75}
  76