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x86: Copy the FPU/XSAVE state from the creating thread to new threads.

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POSIX states that new threads created via pthread_create() should
inherit the "floating point environment" from the creating thread.

Discussed with:	kib
MFC after:	1 week
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D29204
This commit is contained in:
John Baldwin 2021-03-12 09:47:41 -08:00
parent 704547ce1c
commit 755efb8d8f
2 changed files with 15 additions and 7 deletions
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10
sys/amd64/amd64/vm_machdep.c
View File

@ -564,16 +564,18 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
pcb2 = td->td_pcb;
/* Ensure that td0's pcb is up to date. */
fpuexit(td0);
if (td0 == curthread)
update_pcb_bases(td0->td_pcb);
/*
* Copy the upcall pcb. This loads kernel regs.
* Those not loaded individually below get their default
* values here.
*/
if (td0 == curthread)
update_pcb_bases(td0->td_pcb);
bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
clear_pcb_flags(pcb2, PCB_FPUINITDONE | PCB_USERFPUINITDONE |
PCB_KERNFPU);
clear_pcb_flags(pcb2, 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);

12
sys/i386/i386/vm_machdep.c
View File

@ -428,14 +428,21 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
/* Point the pcb to the top of the stack. */
pcb2 = td->td_pcb;
/* Ensure that td0's pcb is up to date. */
if (td0 == curthread)
td0->td_pcb->pcb_gs = rgs();
critical_enter();
if (PCPU_GET(fpcurthread) == td0)
npxsave(td0->td_pcb->pcb_save);
critical_exit();
/*
* Copy the upcall pcb. This loads kernel regs.
* Those not loaded individually below get their default
* values here.
*/
bcopy(td0->td_pcb, pcb2, sizeof(*pcb2));
pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
PCB_KERNNPX);
pcb2->pcb_flags &= ~PCB_KERNNPX;
pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);
bcopy(get_pcb_user_save_td(td0), pcb2->pcb_save,
cpu_max_ext_state_size);
@ -463,7 +470,6 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
pcb2->pcb_esp = (int)td->td_frame - sizeof(void *); /* trampoline arg */
pcb2->pcb_ebx = (int)td; /* trampoline arg */
pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
pcb2->pcb_gs = rgs();
/*
* If we didn't copy the pcb, we'd need to do the following registers:
* pcb2->pcb_cr3: cloned above.