This patch addresses a bug that can cause a GPF in the kernel - if a
process makes use of i386_set_ldt to install a LDT entry, then loads
a corresponding segment descriptor into %gs, forks, and if the child
execs.
In this scenario, setregs executes user_ldt_free and then determines
how to reset the %gs register:
/* reset %gs as well */
if (pcb == curpcb)
load_gs(_udatasel);
else
pcb->pcb_gs = _udatasel;
This is insufficient in the fork/exec case, since pcb will be equal
to curpcb when the child execs; load_gs will reset %gs to _udatasel
but it doesn't reset pcb->pcb_gs; upon return from the system call,
cpu_switch_load_gs will thus attempt to restore %gs from pcb->pcb_gs
and trigger a GPF since all LDT entries have already been cleared.
The fix is to always reset pcb->pcb_gs to _udatasel.
Submitted by: Christian Zander <zander@minion.de>
Reviewed by: jake
wasn't doing. Rather than just lock and unlock the vnode around the call
to VOP_FSYNC(), implement rwatson's suggestion to lock the file vnode
in kern_link() before calling VOP_LINK(), since the other filesystems
also locked the file vnode right away in their link methods. Remove the
locking and and unlocking from the leaf filesystem link methods.
Reviewed by: rwatson, bde (except for the unionfs_link() changes)
and wide characters. These were already documented in the manual page,
with an entry mentioning that they were not implemented yet. The XSI
%S and %C synoyms have not been added.
header and return that length, was misguided.
The check itself didn't take into account the fact that the
mbuf pointer pased in may be null, and the function is
defined specifically for cases where the caller knows what it wants.
Rather than fix the check I'm removing it as phk suggested.
Submitted by: phk@freebsd.org
- remove test in pmap_activate that prevented vmspace sharing (v/rfork)
- always sync icache in pmap_enter until problems are sorted
- fix incorrect use of regions in pmap_kenter
- bring in pmap_release from NetBSD
- fix overwrite of bootstrap flag in pmap_pvo_enter
Approved by: benno
- sysctl for cacheline size, required by libc/rtld
- init'd more exception vectors
- fixed problem with register overwrite in exec_setregs
- removed redundant NetBSD code
Approved by: benno
