From f8bd2f9739571a0d6b5f8b191bc058f53b4cc7bc Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Sat, 10 Aug 2024 05:08:04 -0400
Subject: [PATCH] synchronize usertests and exec with util lab
---
kernel/exec.c | 10 +++++-----
kernel/param.h | 2 ++
user/usertests.c | 9 +++++++--
3 files changed, 14 insertions(+), 7 deletions(-)
diff --git a/kernel/exec.c b/kernel/exec.c
index e18bbb6..6d7c452 100644
--- a/kernel/exec.c
+++ b/kernel/exec.c
@@ -75,17 +75,17 @@ exec(char *path, char **argv)
p = myproc();
uint64 oldsz = p->sz;
- // Allocate two pages at the next page boundary.
+ // Allocate some pages at the next page boundary.
// Make the first inaccessible as a stack guard.
- // Use the second as the user stack.
+ // Use the rest as the user stack.
sz = PGROUNDUP(sz);
uint64 sz1;
- if((sz1 = uvmalloc(pagetable, sz, sz + 2*PGSIZE, PTE_W)) == 0)
+ if((sz1 = uvmalloc(pagetable, sz, sz + (USERSTACK+1)*PGSIZE, PTE_W)) == 0)
goto bad;
sz = sz1;
- uvmclear(pagetable, sz-2*PGSIZE);
+ uvmclear(pagetable, sz-(USERSTACK+1)*PGSIZE);
sp = sz;
- stackbase = sp - PGSIZE;
+ stackbase = sp - USERSTACK*PGSIZE;
// Push argument strings, prepare rest of stack in ustack.
for(argc = 0; argv[argc]; argc++) {
diff --git a/kernel/param.h b/kernel/param.h
index 6624bff..80ec6d3 100644
--- a/kernel/param.h
+++ b/kernel/param.h
@@ -11,3 +11,5 @@
#define NBUF (MAXOPBLOCKS*3) // size of disk block cache
#define FSSIZE 2000 // size of file system in blocks
#define MAXPATH 128 // maximum file path name
+#define USERSTACK 1 // user stack pages
+
diff --git a/user/usertests.c b/user/usertests.c
index d9c21b9..28b53f9 100644
--- a/user/usertests.c
+++ b/user/usertests.c
@@ -2310,9 +2310,14 @@ bigargtest(char *s)
if(pid == 0){
static char *args[MAXARG];
int i;
+ char big[400];
+ memset(big, ' ', sizeof(big));
+ big[sizeof(big)-1] = '\0';
for(i = 0; i < MAXARG-1; i++)
- args[i] = "bigargs test: failed\n ";
+ args[i] = big;
args[MAXARG-1] = 0;
+ // this exec() should fail (and return) because the
+ // arguments are too large.
exec("echo", args);
fd = open("bigarg-ok", O_CREATE);
close(fd);
@@ -2409,7 +2414,7 @@ stacktest(char *s)
pid = fork();
if(pid == 0) {
char *sp = (char *) r_sp();
- sp -= PGSIZE;
+ sp -= USERSTACK*PGSIZE;
// the *sp should cause a trap.
printf("%s: stacktest: read below stack %d\n", s, *sp);
exit(1);