Imbus/xv6-riscv-kernel
1
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

inaccessible page under the user stack page, to help exec deal w/ too-large args

Browse source
This commit is contained in:
Robert Morris 2011-09-01 13:25:34 -04:00
parent 62e3b8a92c
commit 371ab7fa96
4 changed files with 21 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

9
exec.c
View file

@ -49,13 +49,16 @@ exec(char *path, char **argv)
iunlockput(ip);
ip = 0;
// Allocate a one-page stack at the next page boundary
// Allocate two pages at the next page boundary.
// Make the first inaccessible.
// Use the second as the user stack.
sz = PGROUNDUP(sz);
if((sz = allocuvm(pgdir, sz, sz + PGSIZE)) == 0)
if((sz = allocuvm(pgdir, sz, sz + 2*PGSIZE)) == 0)
goto bad;
clear_pte_u(pgdir, (char*)(sz-2*PGSIZE));
sp = sz;
// Push argument strings, prepare rest of stack in ustack.
sp = sz;
for(argc = 0; argv[argc]; argc++) {
if(argc >= MAXARG)
goto bad;