diff options
author | Frans Kaashoek <[email protected]> | 2019-07-19 08:38:51 -0400 |
---|---|---|
committer | Frans Kaashoek <[email protected]> | 2019-07-19 08:38:51 -0400 |
commit | 91566327012cad2ca99df47f9321dfc012d8a7ff (patch) | |
tree | e9cb082d502a9f56857270264bea254149a3318d /kernel/defs.h | |
parent | b924e44f06c9c0882a2cffe6c9215b12c5aee2e6 (diff) | |
download | xv6-labs-91566327012cad2ca99df47f9321dfc012d8a7ff.tar.gz xv6-labs-91566327012cad2ca99df47f9321dfc012d8a7ff.tar.bz2 xv6-labs-91566327012cad2ca99df47f9321dfc012d8a7ff.zip |
One way of supporting a guard page below kstack: allocate kstacks in
procinit() and map them high up (below TRAMPOLNE) with an empty
mapping below each stack. Never free a kernel stack.
Another way would be to allocate and map them dynamically, but then we
need to reload page table when switching processes in scheduler()
and/or have a kernel pagetable per proc (if we want k->stack to be the
same virtual address in each process).
One gotcha: kernel addresses are not equal to physical addresses for
stack addresses. A stack address must be translated if we need its
physical address (e.g., virtio passes a stack address to the disk).
Diffstat (limited to 'kernel/defs.h')
-rw-r--r-- | kernel/defs.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/defs.h b/kernel/defs.h index bd89af0..3172cb3 100644 --- a/kernel/defs.h +++ b/kernel/defs.h @@ -193,6 +193,8 @@ uint64 walkaddr(pagetable_t, uint64); int copyout(pagetable_t, uint64, char *, uint64); int copyin(pagetable_t, char *, uint64, uint64); int copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max); +char* map_kstack(); +uint64 kernelpa(uint64); // plic.c void plicinit(void); |