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/* $OpenBSD: vfp.c,v 1.2 2018/03/16 21:46:04 kettenis Exp $ */
/*
* Copyright (c) 2011 Dale Rahn <drahn@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/user.h>
#include <arm/include/cpufunc.h>
#include <arm/include/vfp.h>
#include <arm/include/undefined.h>
static inline void
set_vfp_fpexc(uint32_t val)
{
__asm __volatile("vmsr fpexc, %0" :: "r" (val));
}
static inline uint32_t
get_vfp_fpexc(void)
{
uint32_t val;
__asm __volatile("vmrs %0, fpexc" : "=r" (val));
return val;
}
int vfp_fault(unsigned int, unsigned int, trapframe_t *, int);
void vfp_load(struct proc *p);
void vfp_store(struct fpreg *vfpsave);
void
vfp_init(void)
{
uint32_t val;
install_coproc_handler(10, vfp_fault);
install_coproc_handler(11, vfp_fault);
__asm volatile("mrc p15, 0, %0, c1, c0, 2" : "=r" (val));
val |= COPROC10 | COPROC11;
__asm volatile("mcr p15, 0, %0, c1, c0, 2" :: "r" (val));
__asm volatile("isb");
}
void
vfp_store(struct fpreg *vfpsave)
{
uint32_t scratch;
if (get_vfp_fpexc() & VFPEXC_EN) {
__asm __volatile(
"vstmia %1!, {d0-d15}\n" /* d0-d15 */
"vstmia %1!, {d16-d31}\n" /* d16-d31 */
"vmrs %0, fpscr\n"
"str %0, [%1]\n" /* save vfpscr */
: "=&r" (scratch) : "r" (vfpsave));
}
/* disable FPU */
set_vfp_fpexc(0);
}
void
vfp_save(void)
{
struct cpu_info *ci = curcpu();
struct pcb *pcb = curpcb;
struct proc *p = curproc;
uint32_t cr_8;
if (ci->ci_fpuproc == 0)
return;
cr_8 = get_vfp_fpexc();
if ((cr_8 & VFPEXC_EN) == 0)
return; /* not enabled, nothing to do */
if (cr_8 & VFPEXC_EX)
panic("vfp exceptional data fault, time to write more code");
if (pcb->pcb_fpcpu == NULL || ci->ci_fpuproc == NULL ||
!(pcb->pcb_fpcpu == ci && ci->ci_fpuproc == p)) {
/* disable fpu before panic, otherwise recurse */
set_vfp_fpexc(0);
panic("FPU unit enabled when curproc and curcpu dont agree %p %p %p %p", pcb->pcb_fpcpu, ci, ci->ci_fpuproc, p);
}
vfp_store(&p->p_addr->u_pcb.pcb_fpstate);
/*
* NOTE: fpu state is saved but remains 'valid', as long as
* curpcb()->pcb_fpucpu == ci && ci->ci_fpuproc == curproc()
* is true FPU state is valid and can just be enabled without reload.
*/
}
void
vfp_enable(void)
{
struct cpu_info *ci = curcpu();
if (curproc->p_addr->u_pcb.pcb_fpcpu == ci &&
ci->ci_fpuproc == curproc) {
disable_interrupts(PSR_I|PSR_F);
/* FPU state is still valid, just enable and go */
set_vfp_fpexc(VFPEXC_EN);
}
}
void
vfp_load(struct proc *p)
{
struct cpu_info *ci = curcpu();
struct pcb *pcb = &p->p_addr->u_pcb;
uint32_t scratch = 0;
int psw;
/* do not allow a partially synced state here */
psw = disable_interrupts(PSR_I|PSR_F);
/*
* p->p_pcb->pcb_fpucpu _may_ not be NULL here, but the FPU state
* was synced on kernel entry, so we can steal the FPU state
* instead of signalling and waiting for it to save
*/
/* enable to be able to load ctx */
set_vfp_fpexc(VFPEXC_EN);
__asm __volatile(
"vldmia %1!, {d0-d15}\n" /* d0-d15 */
"vldmia %1!, {d16-d31}\n" /* d16-d31 */
"ldr %0, [%1]\n" /* set old vfpscr */
"vmsr fpscr, %0\n"
: "=&r" (scratch) : "r" (&pcb->pcb_fpstate));
ci->ci_fpuproc = p;
pcb->pcb_fpcpu = ci;
/* disable until return to userland */
set_vfp_fpexc(0);
restore_interrupts(psw);
}
int
vfp_fault(unsigned int pc, unsigned int insn, trapframe_t *tf, int fault_code)
{
struct proc *p = curproc;
struct pcb *pcb = &p->p_addr->u_pcb;
if (get_vfp_fpexc() & VFPEXC_EN) {
/*
* We probably ran into an unsupported instruction,
* like NEON on a non-NEON system. Let the process know.
*/
return 1;
}
/* we should be able to ignore old state of pcb_fpcpu ci_fpuproc */
if ((pcb->pcb_flags & PCB_FPU) == 0) {
pcb->pcb_flags |= PCB_FPU;
memset(&pcb->pcb_fpstate, 0, sizeof(pcb->pcb_fpstate));
}
vfp_load(p);
return 0;
}
void
vfp_discard(struct proc *p)
{
struct cpu_info *ci = curcpu();
if (curpcb->pcb_fpcpu == ci && ci->ci_fpuproc == p) {
ci->ci_fpuproc = NULL;
curpcb->pcb_fpcpu = NULL;
}
}
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