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Seemingly implement system calls (still appears to have a bug).

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This commit is contained in:
Danila Fedorin 2019-04-23 16:14:41 -07:00
parent bbdb8bd811
commit eae0475758
2 changed files with 34 additions and 3 deletions
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30
kern/syscall.c
View File

@ -19,8 +19,25 @@ sys_cputs(const char *s, size_t len)
{
// Check that the user has permission to read memory [s, s+len).
// Destroy the environment if not.
const char* bottom = ROUNDDOWN(s, PGSIZE);
size_t aligned_count = ROUNDUP(len, PGSIZE) / PGSIZE;
while(aligned_count--) {
if (!(curenv->env_pgdir[PDX(bottom)] & PTE_P)) {
cprintf("[%08x] Tried to print unmapped address\n", curenv->env_id);
env_destroy(curenv);
return;
}
// LAB 3: Your code here.
pde_t pgdir_allowed = curenv->env_pgdir[PDX(bottom)] & PTE_U;
pde_t pt_allowed = *pgdir_walk(curenv->env_pgdir, bottom, 0) & PTE_U;
if(((curenv->env_tf.tf_cs & 0b11) > 1) && !(pt_allowed & pgdir_allowed)) {
cprintf("[%08x] Tried to print forbidden memory\n", curenv->env_id);
env_destroy(curenv);
return;
}
bottom += PGSIZE;
}
// Print the string supplied by the user.
cprintf("%.*s", len, s);
@ -70,9 +87,16 @@ syscall(uint32_t syscallno, uint32_t a1, uint32_t a2, uint32_t a3, uint32_t a4,
// Return any appropriate return value.
// LAB 3: Your code here.
panic("syscall not implemented");
switch (syscallno) {
case SYS_cputs:
sys_cputs((const char*) a1, a2);
return 0;
case SYS_cgetc:
return sys_cgetc();
case SYS_getenvid:
return sys_getenvid();
case SYS_env_destroy:
return sys_env_destroy(a1);
default:
return -E_INVAL;
}

7
kern/trap.c
View File

@ -200,6 +200,13 @@ trap_dispatch(struct Trapframe *tf)
page_fault_handler(tf);
} else if (tf->tf_trapno == T_BRKPT) {
monitor(tf);
} else if (tf->tf_trapno == T_SYSCALL) {
syscall(tf->tf_regs.reg_eax,
tf->tf_regs.reg_edx,
tf->tf_regs.reg_ecx,
tf->tf_regs.reg_ebx,
tf->tf_regs.reg_edi,
tf->tf_regs.reg_esi);
}
// Unexpected trap: The user process or the kernel has a bug.