Author: kib
Date: Wed Oct 7 09:12:49 2015
New Revision: 288983
URL: https://svnweb.freebsd.org/changeset/base/288983
Log:
A follow-up to r288492. In fact, revert the mentioned commit for
pre-VFPv3 processors, since they do require software support code to
handle denormals. For VFPv3 and later, enable flush-to-zero if
hardware does not claim full denormals arithmetic support by VMVFR1_FZ
field in mvfr1 register.
The end result is that we do use correct fpu environment on Cortexes
with VFPv3, while ARM11 (e.g. rpi) is in non-compliant flush-to-zero
mode. At least CPUs without complete hardware implementation of
IEEE 754 do not cause unhandled floating point exception on underflow,
as it was before r288492.
Noted by: ian
Tested by: gjb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/sys/arm/arm/vfp.c
head/sys/arm/arm/vm_machdep.c
head/sys/arm/include/md_var.h
Modified: head/sys/arm/arm/vfp.c
==============================================================================
--- head/sys/arm/arm/vfp.c Wed Oct 7 08:56:38 2015 (r288982)
+++ head/sys/arm/arm/vfp.c Wed Oct 7 09:12:49 2015 (r288983)
@@ -38,6 +38,7 @@ __FBSDID("$FreeBSD$");
#include <machine/armreg.h>
#include <machine/frame.h>
#include <machine/fp.h>
+#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/undefined.h>
#include <machine/vfp.h>
@@ -128,6 +129,15 @@ vfp_init(void)
tmp = fmrx(mvfr1);
PCPU_SET(vfpmvfr1, tmp);
+
+ if (PCPU_GET(cpuid) == 0) {
+ if ((tmp & VMVFR1_FZ_MASK) == 0x1) {
+ /* Denormals arithmetic support */
+ initial_fpscr &= ~VFPSCR_FZ;
+ thread0.td_pcb->pcb_vfpstate.fpscr =
+ initial_fpscr;
+ }
+ }
}
/* initialize the coprocess 10 and 11 calls
Modified: head/sys/arm/arm/vm_machdep.c
==============================================================================
--- head/sys/arm/arm/vm_machdep.c Wed Oct 7 08:56:38 2015
(r288982)
+++ head/sys/arm/arm/vm_machdep.c Wed Oct 7 09:12:49 2015
(r288983)
@@ -85,6 +85,8 @@ __FBSDID("$FreeBSD$");
CTASSERT(sizeof(struct switchframe) == 48);
CTASSERT(sizeof(struct trapframe) == 80);
+uint32_t initial_fpscr = VFPSCR_DN | VFPSCR_FZ;
+
/*
* Finish a fork operation, with process p2 nearly set up.
* Copy and update the pcb, set up the stack so that the child
@@ -134,7 +136,7 @@ cpu_fork(register struct thread *td1, re
pcb2->pcb_regs.sf_sp = STACKALIGN(td2->td_frame);
pcb2->pcb_vfpcpu = -1;
- pcb2->pcb_vfpstate.fpscr = VFPSCR_DN;
+ pcb2->pcb_vfpstate.fpscr = initial_fpscr;
tf = td2->td_frame;
tf->tf_spsr &= ~PSR_C;
Modified: head/sys/arm/include/md_var.h
==============================================================================
--- head/sys/arm/include/md_var.h Wed Oct 7 08:56:38 2015
(r288982)
+++ head/sys/arm/include/md_var.h Wed Oct 7 09:12:49 2015
(r288983)
@@ -71,4 +71,6 @@ void dump_add_page(vm_paddr_t);
void dump_drop_page(vm_paddr_t);
int minidumpsys(struct dumperinfo *);
+extern uint32_t initial_fpscr;
+
#endif /* !_MACHINE_MD_VAR_H_ */
_______________________________________________
svn-src-head@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
