semihosting/uaccess.c

   1 /*
   2  * Helper routines to provide target memory access for semihosting
   3  * syscalls in system emulation mode.
   4  *
   5  * Copyright (c) 2007 CodeSourcery.
   6  *
   7  * This code is licensed under the GPL
   8  */
   9
  10 #include "qemu/osdep.h"
  11 #include "exec/exec-all.h"
  12 #include "semihosting/uaccess.h"
  13
  14 void *uaccess_lock_user(CPUArchState *env, target_ulong addr,
  15                         target_ulong len, bool copy)
  16 {
  17     void *p = malloc(len);
  18     if (p && copy) {
  19         if (cpu_memory_rw_debug(env_cpu(env), addr, p, len, 0)) {
  20             free(p);
  21             p = NULL;
  22         }
  23     }
  24     return p;
  25 }
  26
  27 ssize_t uaccess_strlen_user(CPUArchState *env, target_ulong addr)
  28 {
  29     int mmu_idx = cpu_mmu_index(env_cpu(env), false);
  30     size_t len = 0;
  31
  32     while (1) {
  33         size_t left_in_page;
  34         int flags;
  35         void *h;
  36
  37         /* Find the number of bytes remaining in the page. */
  38         left_in_page = TARGET_PAGE_SIZE - (addr & ~TARGET_PAGE_MASK);
  39
  40         flags = probe_access_flags(env, addr, 0, MMU_DATA_LOAD,
  41                                    mmu_idx, true, &h, 0);
  42         if (flags & TLB_INVALID_MASK) {
  43             return -1;
  44         }
  45         if (flags & TLB_MMIO) {
  46             do {
  47                 uint8_t c;
  48                 if (cpu_memory_rw_debug(env_cpu(env), addr, &c, 1, 0)) {
  49                     return -1;
  50                 }
  51                 if (c == 0) {
  52                     return len;
  53                 }
  54                 addr++;
  55                 len++;
  56                 if (len > INT32_MAX) {
  57                     return -1;
  58                 }
  59             } while (--left_in_page != 0);
  60         } else {
  61             char *p = memchr(h, 0, left_in_page);
  62             if (p) {
  63                 len += p - (char *)h;
  64                 return len <= INT32_MAX ? (ssize_t)len : -1;
  65             }
  66             addr += left_in_page;
  67             len += left_in_page;
  68             if (len > INT32_MAX) {
  69                 return -1;
  70             }
  71         }
  72     }
  73 }
  74
  75 char *uaccess_lock_user_string(CPUArchState *env, target_ulong addr)
  76 {
  77     ssize_t len = uaccess_strlen_user(env, addr);
  78     if (len < 0) {
  79         return NULL;
  80     }
  81     return uaccess_lock_user(env, addr, len + 1, true);
  82 }
  83
  84 void uaccess_unlock_user(CPUArchState *env, void *p,
  85                          target_ulong addr, target_ulong len)
  86 {
  87     if (len) {
  88         cpu_memory_rw_debug(env_cpu(env), addr, p, len, 1);
  89     }
  90     free(p);
  91 }