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
  18 int 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
  35 void 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  */
  58 target_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 }