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1 #include "types.h"
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2 #include "defs.h"
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3 #include "param.h"
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4 #include "memlayout.h"
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5 #include "mmu.h"
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6 #include "proc.h"
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7 #include "arm.h"
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8 #include "syscall.h"
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9
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10 // User code makes a system call with INT T_SYSCALL. System call number
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11 // in r0. Arguments on the stack, from the user call to the C library
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12 // system call function. The saved user sp points to the first argument.
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13
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14 // Fetch the int at addr from the current process.
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15 int fetchint(uint addr, int *ip)
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16 {
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17 if(addr >= proc->sz || addr+4 > proc->sz) {
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18 return -1;
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19 }
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20
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21 *ip = *(int*)(addr);
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22 return 0;
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23 }
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24
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25 // Fetch the nul-terminated string at addr from the current process.
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26 // Doesn't actually copy the string - just sets *pp to point at it.
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27 // Returns length of string, not including nul.
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28 int fetchstr(uint addr, char **pp)
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29 {
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30 char *s, *ep;
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31
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32 if(addr >= proc->sz) {
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33 return -1;
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34 }
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35
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36 *pp = (char*)addr;
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37 ep = (char*)proc->sz;
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38
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39 for(s = *pp; s < ep; s++) {
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40 if(*s == 0) {
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41 return s - *pp;
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42 }
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43 }
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44
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45 return -1;
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46 }
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47
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48 // Fetch the nth (starting from 0) 32-bit system call argument.
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49 // In our ABI, r0 contains system call index, r1-r4 contain parameters.
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50 // now we support system calls with at most 4 parameters.
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51 int argint(int n, int *ip)
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52 {
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53 if (n > 3) {
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54 panic ("too many system call parameters\n");
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55 }
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56
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57 *ip = *(&proc->tf->r1 + n);
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58
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59 return 0;
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60 }
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61
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62 // Fetch the nth word-sized system call argument as a pointer
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63 // to a block of memory of size n bytes. Check that the pointer
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64 // lies within the process address space.
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65 int argptr(int n, char **pp, int size)
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66 {
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67 int i;
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68
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69 if(argint(n, &i) < 0) {
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70 return -1;
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71 }
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72
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73 if((uint)i >= proc->sz || (uint)i+size > proc->sz) {
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74 return -1;
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75 }
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76
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77 *pp = (char*)i;
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78 return 0;
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79 }
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80
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81 // Fetch the nth word-sized system call argument as a string pointer.
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82 // Check that the pointer is valid and the string is nul-terminated.
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83 // (There is no shared writable memory, so the string can't change
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84 // between this check and being used by the kernel.)
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85 int argstr(int n, char **pp)
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86 {
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87 int addr;
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88
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89 if(argint(n, &addr) < 0) {
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90 return -1;
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91 }
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92
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93 return fetchstr(addr, pp);
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94 }
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95
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96 extern int sys_chdir(void);
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97 extern int sys_close(void);
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98 extern int sys_dup(void);
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99 extern int sys_exec(void);
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100 extern int sys_exit(void);
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101 extern int sys_fork(void);
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102 extern int sys_fstat(void);
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103 extern int sys_getpid(void);
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104 extern int sys_kill(void);
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105 extern int sys_link(void);
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106 extern int sys_mkdir(void);
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107 extern int sys_mknod(void);
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108 extern int sys_open(void);
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109 extern int sys_pipe(void);
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110 extern int sys_read(void);
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111 extern int sys_sbrk(void);
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112 extern int sys_sleep(void);
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113 extern int sys_unlink(void);
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114 extern int sys_wait(void);
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115 extern int sys_write(void);
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116 extern int sys_uptime(void);
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117
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118 static int (*syscalls[])(void) = {
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22
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119 [SYS_fork] =sys_fork,
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120 [SYS_exit] =sys_exit,
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121 [SYS_wait] =sys_wait,
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122 [SYS_pipe] =sys_pipe,
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123 [SYS_read] =sys_read,
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124 [SYS_kill] =sys_kill,
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125 [SYS_exec] =sys_exec,
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126 [SYS_fstat] =sys_fstat,
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127 [SYS_chdir] =sys_chdir,
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128 [SYS_dup] =sys_dup,
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129 [SYS_getpid] =sys_getpid,
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130 [SYS_sbrk] =sys_sbrk,
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131 [SYS_sleep] =sys_sleep,
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132 [SYS_uptime] =sys_uptime,
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133 [SYS_open] =sys_open,
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134 [SYS_write] =sys_write,
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135 [SYS_mknod] =sys_mknod,
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136 [SYS_unlink] =sys_unlink,
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137 [SYS_link] =sys_link,
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138 [SYS_mkdir] =sys_mkdir,
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139 [SYS_close] =sys_close,
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0
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140 };
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141
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24
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142 static __code (*cbccodes[])(void) = {
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143 [SYS_cbc_read] = cbc_read,
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144 };
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145
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146 __code cbc_ret(int ret){
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147 proc->tf->r0 = ret;
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148 goto cbc_trap_return();
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149 }
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150
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151 void syscall(void)
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152 {
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153 int num;
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154 int ret;
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155
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156 num = proc->tf->r0;
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157
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158 //cprintf ("syscall(%d) from %s(%d)\n", num, proc->name, proc->pid);
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159
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160 if((num > 0) && (num > NELEM(syscalls)) && cbccodes[num]) {
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161
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162 goto (cbccodes[num])(cbc_ret);
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163 }
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164
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165
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0
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166 if((num > 0) && (num <= NELEM(syscalls)) && syscalls[num]) {
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167 ret = syscalls[num]();
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168
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169 // in ARM, parameters to main (argc, argv) are passed in r0 and r1
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170 // do not set the return value if it is SYS_exec (the user program
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171 // anyway does not expect us to return anything).
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172 if (num != SYS_exec) {
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173 proc->tf->r0 = ret;
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174 }
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175 } else {
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176 cprintf("%d %s: unknown sys call %d\n", proc->pid, proc->name, num);
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177 proc->tf->r0 = -1;
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178 }
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179 }
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