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f-stack/freebsd/arm/arm/vfp.c

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/*-
* Copyright (c) 2014 Ian Lepore <ian@freebsd.org>
* Copyright (c) 2012 Mark Tinguely
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#ifdef VFP
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#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>
/* function prototypes */
static int vfp_bounce(u_int, u_int, struct trapframe *, int);
static void vfp_restore(struct vfp_state *);
extern int vfp_exists;
static struct undefined_handler vfp10_uh, vfp11_uh;
/* If true the VFP unit has 32 double registers, otherwise it has 16 */
static int is_d32;
/*
* About .fpu directives in this file...
*
* We should need simply .fpu vfpv3, but clang 3.5 has a quirk where setting
* vfpv3 doesn't imply that vfp2 features are also available -- both have to be
* explicitly set to get all the features of both. This is probably a bug in
* clang, so it may get fixed and require changes here some day. Other changes
* are probably coming in clang too, because there is email and open PRs
* indicating they want to completely disable the ability to use .fpu and
* similar directives in inline asm. That would be catastrophic for us,
* hopefully they come to their senses. There was also some discusion of a new
* syntax such as .push fpu=vfpv3; ...; .pop fpu; and that would be ideal for
* us, better than what we have now really.
*
* For gcc, each .fpu directive completely overrides the prior directive, unlike
* with clang, but luckily on gcc saying v3 implies all the v2 features as well.
*/
#define fmxr(reg, val) \
__asm __volatile(" .fpu vfpv2\n .fpu vfpv3\n" \
" vmsr " __STRING(reg) ", %0" :: "r"(val));
#define fmrx(reg) \
({ u_int val = 0;\
__asm __volatile(" .fpu vfpv2\n .fpu vfpv3\n" \
" vmrs %0, " __STRING(reg) : "=r"(val)); \
val; \
})
static u_int
get_coprocessorACR(void)
{
u_int val;
__asm __volatile("mrc p15, 0, %0, c1, c0, 2" : "=r" (val) : : "cc");
return val;
}
static void
set_coprocessorACR(u_int val)
{
__asm __volatile("mcr p15, 0, %0, c1, c0, 2\n\t"
: : "r" (val) : "cc");
isb();
}
/* called for each cpu */
void
vfp_init(void)
{
u_int fpsid, fpexc, tmp;
u_int coproc, vfp_arch;
coproc = get_coprocessorACR();
coproc |= COPROC10 | COPROC11;
set_coprocessorACR(coproc);
fpsid = fmrx(fpsid); /* read the vfp system id */
fpexc = fmrx(fpexc); /* read the vfp exception reg */
if (!(fpsid & VFPSID_HARDSOFT_IMP)) {
vfp_exists = 1;
is_d32 = 0;
PCPU_SET(vfpsid, fpsid); /* save the fpsid */
vfp_arch =
(fpsid & VFPSID_SUBVERSION2_MASK) >> VFPSID_SUBVERSION_OFF;
if (vfp_arch >= VFP_ARCH3) {
tmp = fmrx(mvfr0);
PCPU_SET(vfpmvfr0, tmp);
if ((tmp & VMVFR0_RB_MASK) == 2)
is_d32 = 1;
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
* These are called to restore the registers and enable
* the VFP hardware.
*/
if (vfp10_uh.uh_handler == NULL) {
vfp10_uh.uh_handler = vfp_bounce;
vfp11_uh.uh_handler = vfp_bounce;
install_coproc_handler_static(10, &vfp10_uh);
install_coproc_handler_static(11, &vfp11_uh);
}
}
}
SYSINIT(vfp, SI_SUB_CPU, SI_ORDER_ANY, vfp_init, NULL);
/* start VFP unit, restore the vfp registers from the PCB and retry
* the instruction
*/
static int
vfp_bounce(u_int addr, u_int insn, struct trapframe *frame, int code)
{
u_int cpu, fpexc;
struct pcb *curpcb;
ksiginfo_t ksi;
if ((code & FAULT_USER) == 0)
panic("undefined floating point instruction in supervisor mode");
critical_enter();
/*
* If the VFP is already on and we got an undefined instruction, then
* something tried to executate a truly invalid instruction that maps to
* the VFP.
*/
fpexc = fmrx(fpexc);
if (fpexc & VFPEXC_EN) {
/* Clear any exceptions */
fmxr(fpexc, fpexc & ~(VFPEXC_EX | VFPEXC_FP2V));
/* kill the process - we do not handle emulation */
critical_exit();
if (fpexc & VFPEXC_EX) {
/* We have an exception, signal a SIGFPE */
ksiginfo_init_trap(&ksi);
ksi.ksi_signo = SIGFPE;
if (fpexc & VFPEXC_UFC)
ksi.ksi_code = FPE_FLTUND;
else if (fpexc & VFPEXC_OFC)
ksi.ksi_code = FPE_FLTOVF;
else if (fpexc & VFPEXC_IOC)
ksi.ksi_code = FPE_FLTINV;
ksi.ksi_addr = (void *)addr;
trapsignal(curthread, &ksi);
return 0;
}
return 1;
}
/*
* If the last time this thread used the VFP it was on this core, and
* the last thread to use the VFP on this core was this thread, then the
* VFP state is valid, otherwise restore this thread's state to the VFP.
*/
fmxr(fpexc, fpexc | VFPEXC_EN);
curpcb = curthread->td_pcb;
cpu = PCPU_GET(cpuid);
if (curpcb->pcb_vfpcpu != cpu || curthread != PCPU_GET(fpcurthread)) {
vfp_restore(&curpcb->pcb_vfpstate);
curpcb->pcb_vfpcpu = cpu;
PCPU_SET(fpcurthread, curthread);
}
critical_exit();
return (0);
}
/*
* Restore the given state to the VFP hardware.
*/
static void
vfp_restore(struct vfp_state *vfpsave)
{
uint32_t fpexc;
/* On vfpv3 we may need to restore FPINST and FPINST2 */
fpexc = vfpsave->fpexec;
if (fpexc & VFPEXC_EX) {
fmxr(fpinst, vfpsave->fpinst);
if (fpexc & VFPEXC_FP2V)
fmxr(fpinst2, vfpsave->fpinst2);
}
fmxr(fpscr, vfpsave->fpscr);
__asm __volatile(
" .fpu vfpv2\n"
" .fpu vfpv3\n"
" vldmia %0!, {d0-d15}\n" /* d0-d15 */
" cmp %1, #0\n" /* -D16 or -D32? */
" vldmiane %0!, {d16-d31}\n" /* d16-d31 */
" addeq %0, %0, #128\n" /* skip missing regs */
: "+&r" (vfpsave) : "r" (is_d32) : "cc"
);
fmxr(fpexc, fpexc);
}
/*
* If the VFP is on, save its current state and turn it off if requested to do
* so. If the VFP is not on, does not change the values at *vfpsave. Caller is
* responsible for preventing a context switch while this is running.
*/
void
vfp_store(struct vfp_state *vfpsave, boolean_t disable_vfp)
{
uint32_t fpexc;
fpexc = fmrx(fpexc); /* Is the vfp enabled? */
if (fpexc & VFPEXC_EN) {
vfpsave->fpexec = fpexc;
vfpsave->fpscr = fmrx(fpscr);
/* On vfpv3 we may need to save FPINST and FPINST2 */
if (fpexc & VFPEXC_EX) {
vfpsave->fpinst = fmrx(fpinst);
if (fpexc & VFPEXC_FP2V)
vfpsave->fpinst2 = fmrx(fpinst2);
fpexc &= ~VFPEXC_EX;
}
__asm __volatile(
" .fpu vfpv2\n"
" .fpu vfpv3\n"
" vstmia %0!, {d0-d15}\n" /* d0-d15 */
" cmp %1, #0\n" /* -D16 or -D32? */
" vstmiane r0!, {d16-d31}\n" /* d16-d31 */
" addeq %0, %0, #128\n" /* skip missing regs */
: "+&r" (vfpsave) : "r" (is_d32) : "cc"
);
if (disable_vfp)
fmxr(fpexc , fpexc & ~VFPEXC_EN);
}
}
/*
* The current thread is dying. If the state currently in the hardware belongs
* to the current thread, set fpcurthread to NULL to indicate that the VFP
* hardware state does not belong to any thread. If the VFP is on, turn it off.
* Called only from cpu_throw(), so we don't have to worry about a context
* switch here.
*/
void
vfp_discard(struct thread *td)
{
u_int tmp;
if (PCPU_GET(fpcurthread) == td)
PCPU_SET(fpcurthread, NULL);
tmp = fmrx(fpexc);
if (tmp & VFPEXC_EN)
fmxr(fpexc, tmp & ~VFPEXC_EN);
}
#endif
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