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 "user-internals.h"
  17 #include <termios.h>
  18
  19 int qemu_semihosting_console_outs(CPUArchState *env, target_ulong addr)
  20 {
  21     int len = target_strlen(addr);
  22     void *s;
  23     if (len < 0){
  24        qemu_log_mask(LOG_GUEST_ERROR,
  25                      "%s: passed inaccessible address " TARGET_FMT_lx,
  26                      __func__, addr);
  27        return 0;
  28     }
  29     s = lock_user(VERIFY_READ, addr, (long)(len + 1), 1);
  30     g_assert(s);  /* target_strlen has already verified this will work */
  31     len = write(STDERR_FILENO, s, len);
  32     unlock_user(s, addr, 0);
  33     return len;
  34 }
  35
  36 void qemu_semihosting_console_outc(CPUArchState *env, target_ulong addr)
  37 {
  38     char c;
  39
  40     if (get_user_u8(c, addr)) {
  41         qemu_log_mask(LOG_GUEST_ERROR,
  42                       "%s: passed inaccessible address " TARGET_FMT_lx,
  43                       __func__, addr);
  44     } else {
  45         if (write(STDERR_FILENO, &c, 1) != 1) {
  46             qemu_log_mask(LOG_UNIMP, "%s: unexpected write to stdout failure",
  47                           __func__);
  48         }
  49     }
  50 }
  51
  52 /*
  53  * For linux-user we can safely block. However as we want to return as
  54  * soon as a character is read we need to tweak the termio to disable
  55  * line buffering. We restore the old mode afterwards in case the
  56  * program is expecting more normal behaviour. This is slow but
  57  * nothing using semihosting console reading is expecting to be fast.
  58  */
  59 target_ulong qemu_semihosting_console_inc(CPUArchState *env)
  60 {
  61     uint8_t c;
  62     struct termios old_tio, new_tio;
  63
  64     /* Disable line-buffering and echo */
  65     tcgetattr(STDIN_FILENO, &old_tio);
  66     new_tio = old_tio;
  67     new_tio.c_lflag &= (~ICANON & ~ECHO);
  68     tcsetattr(STDIN_FILENO, TCSANOW, &new_tio);
  69
  70     c = getchar();
  71
  72     /* restore config */
  73     tcsetattr(STDIN_FILENO, TCSANOW, &old_tio);
  74
  75     return (target_ulong) c;
  76 }