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Code Issues Releases Activity

Clear the kernel grab of the FPU state on fork. The pcb_save pointer

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is already correctly reset to the FPU user save area, only PCB_KERNFPU
flag might leak from old thread state into the new state.

For creation of the user-mode thread, the change is nop since
corresponding syscall code does not use FPU.  On the other hand,
creation of a kernel thread forks from a thread selected arbitrary
from proc0, which might use FPU.

Reported and tested by:	Chris Torek <torek@torek.net>
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2014-03-29 11:56:33 +00:00
parent 4797432ff7
commit 65f99c74fb
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=263912
2 changed files with 4 additions and 2 deletions
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3
sys/amd64/amd64/vm_machdep.c
View File

@ -446,7 +446,8 @@ cpu_set_upcall(struct thread *td, struct thread *td0)
* values here.
*/
bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE);
clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE |
PCB_KERNFPU);
pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save,
cpu_max_ext_state_size);

3
sys/i386/i386/vm_machdep.c
View File

@ -457,7 +457,8 @@ cpu_set_upcall(struct thread *td, struct thread *td0)
* values here.
*/
bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE);
pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
PCB_KERNNPX);
pcb2->pcb_save = &pcb2->pcb_user_save;
/*