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Implement the memcheck.

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This commit is contained in:
Danila Fedorin 2019-04-23 20:37:53 -07:00
parent 113093f919
commit 8cd1daf8dd
2 changed files with 17 additions and 20 deletions
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16
kern/pmap.c
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@ -6,6 +6,7 @@
#include <inc/string.h>
#include <inc/assert.h>
#include <kern/monitor.h>
#include <kern/pmap.h>
#include <kern/kclock.h>
#include <kern/env.h>
@ -562,6 +563,21 @@ int
user_mem_check(struct Env *env, const void *va, size_t len, int perm)
{
// LAB 3: Your code here.
const char* bottom = ROUNDDOWN(va, PGSIZE);
size_t aligned_count = ROUNDUP(len, PGSIZE) / PGSIZE;
pde_t mask = PTE_P | PTE_U | PTE_W;
pde_t perms = mask;
#define VALID ((perms & (perm | PTE_P)) == (perm | PTE_P))
#define DO_CHECK if(!VALID) { user_mem_check_addr = (uintptr_t) bottom; return -E_FAULT; }
while(aligned_count--) {
perms &= env->env_pgdir[PDX(bottom)] & mask;
DO_CHECK;
perms &= (*pgdir_walk(env->env_pgdir, bottom, 0)) & mask;
DO_CHECK;
bottom += PGSIZE;
}
return 0;
}

21
kern/syscall.c
View File

@ -19,26 +19,7 @@ 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;
}
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;
}
user_mem_assert(curenv, s, len, 0);
// Print the string supplied by the user.
cprintf("%.*s", len, s);
}