argcheckptr can take a const pointer

a7d4b8fe · Austin Clements · 6f540f24 · a7d4b8fe · a7d4b8fe
--- a/include/kernel.hh
+++ b/include/kernel.hh
@@ -201,7 +201,7 @@ void            destroylock(struct spinlock *lk);
 void            release(struct spinlock*);
 // syscall.c
-int             argcheckptr(void *argval, int);
+int             argcheckptr(const void *argval, int);
 int             argcheckstr(const char*);
 int             fetchint64(uptr, u64*);
 int             fetchstr(char*, const char*, u64);

--- a/kernel/syscall.cc
+++ b/kernel/syscall.cc
@@ -68,7 +68,7 @@ argcheckstr(const char *addr)
 // to a block of memory of size n bytes.  Check that the pointer
 // lies within the process address space.
 int
-argcheckptr(void *p, int size)
+argcheckptr(const void *p, int size)
 {
  u64 i = (u64) p;
  for(uptr va = PGROUNDDOWN(i); va < i+size; va = va + PGSIZE)