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Code Issues Releases Activity

Reorganize code flow in fpudna()/npxdna() to highlight the critical

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section scope.  Sprinkle __predict_false() for conditions known to
never occur or occur only on rare platforms.

Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Konstantin Belousov 2018-06-14 11:09:51 +00:00
parent fa7fad8ab9
commit 5803d744c7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=335132
2 changed files with 20 additions and 21 deletions
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18
sys/amd64/amd64/fpu.c
View File

@ -722,7 +722,7 @@ fpudna(void)
KASSERT((curpcb->pcb_flags & PCB_FPUNOSAVE) == 0,
("fpudna while in fpu_kern_enter(FPU_KERN_NOCTX)"));
if (PCPU_GET(fpcurthread) == td) {
if (__predict_false(PCPU_GET(fpcurthread) == td)) {
/*
* Some virtual machines seems to set %cr0.TS at
* arbitrary moments. Silently clear the TS bit
@ -730,15 +730,15 @@ fpudna(void)
* mode.
*/
stop_emulating();
critical_exit();
return;
} else {
if (__predict_false(PCPU_GET(fpcurthread) != NULL)) {
panic(
"fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n",
PCPU_GET(fpcurthread),
PCPU_GET(fpcurthread)->td_tid, td, td->td_tid);
}
restore_fpu_curthread(td);
}
if (PCPU_GET(fpcurthread) != NULL) {
panic("fpudna: fpcurthread = %p (%d), curthread = %p (%d)\n",
PCPU_GET(fpcurthread), PCPU_GET(fpcurthread)->td_tid,
td, td->td_tid);
}
restore_fpu_curthread(td);
critical_exit();
}

23
sys/i386/i386/npx.c
View File

@ -835,7 +835,7 @@ npxdna(void)
return (0);
td = curthread;
critical_enter();
if (PCPU_GET(fpcurthread) == td) {
if (__predict_false(PCPU_GET(fpcurthread) == td)) {
/*
* Some virtual machines seems to set %cr0.TS at
* arbitrary moments. Silently clear the TS bit
@ -843,19 +843,18 @@ npxdna(void)
* mode.
*/
stop_emulating();
critical_exit();
return (1);
} else {
if (__predict_false(PCPU_GET(fpcurthread) != NULL)) {
printf(
"npxdna: fpcurthread = %p (%d), curthread = %p (%d)\n",
PCPU_GET(fpcurthread),
PCPU_GET(fpcurthread)->td_proc->p_pid,
td, td->td_proc->p_pid);
panic("npxdna");
}
restore_npx_curthread(td, td->td_pcb);
}
if (PCPU_GET(fpcurthread) != NULL) {
printf("npxdna: fpcurthread = %p (%d), curthread = %p (%d)\n",
PCPU_GET(fpcurthread),
PCPU_GET(fpcurthread)->td_proc->p_pid,
td, td->td_proc->p_pid);
panic("npxdna");
}
restore_npx_curthread(td, td->td_pcb);
critical_exit();
return (1);
}