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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/unicore32/kernel/fpu-ucf64.c
*
* Code specific to PKUnity SoC and UniCore ISA
*
* Copyright (C) 2001-2010 GUAN Xue-tao
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched/signal.h>
#include <linux/init.h>
#include <asm/fpu-ucf64.h>
/*
* A special flag to tell the normalisation code not to normalise.
*/
#define F64_NAN_FLAG 0x100
/*
* A bit pattern used to indicate the initial (unset) value of the
* exception mask, in case nothing handles an instruction. This
* doesn't include the NAN flag, which get masked out before
* we check for an error.
*/
#define F64_EXCEPTION_ERROR ((u32)-1 & ~F64_NAN_FLAG)
/*
* Since we aren't building with -mfpu=f64, we need to code
* these instructions using their MRC/MCR equivalents.
*/
#define f64reg(_f64_) #_f64_
#define cff(_f64_) ({ \
u32 __v; \
asm("cff %0, " f64reg(_f64_) "@ fmrx %0, " #_f64_ \
: "=r" (__v) : : "cc"); \
__v; \
})
#define ctf(_f64_, _var_) \
asm("ctf %0, " f64reg(_f64_) "@ fmxr " #_f64_ ", %0" \
: : "r" (_var_) : "cc")
/*
* Raise a SIGFPE for the current process.
* sicode describes the signal being raised.
*/
void ucf64_raise_sigfpe(struct pt_regs *regs)
{
/*
* This is the same as NWFPE, because it's not clear what
* this is used for
*/
current->thread.error_code = 0;
current->thread.trap_no = 6;
send_sig_fault(SIGFPE, FPE_FLTUNK,
(void __user *)(instruction_pointer(regs) - 4),
current);
}
/*
* Handle exceptions of UniCore-F64.
*/
void ucf64_exchandler(u32 inst, u32 fpexc, struct pt_regs *regs)
{
u32 tmp = fpexc;
u32 exc = F64_EXCEPTION_ERROR & fpexc;
pr_debug("UniCore-F64: instruction %08x fpscr %08x\n",
inst, fpexc);
if (exc & FPSCR_CMPINSTR_BIT) {
if (exc & FPSCR_CON)
tmp |= FPSCR_CON;
else
tmp &= ~(FPSCR_CON);
exc &= ~(FPSCR_CMPINSTR_BIT | FPSCR_CON);
} else {
pr_debug("UniCore-F64 Error: unhandled exceptions\n");
pr_debug("UniCore-F64 FPSCR 0x%08x INST 0x%08x\n",
cff(FPSCR), inst);
ucf64_raise_sigfpe(regs);
return;
}
/*
* Update the FPSCR with the additional exception flags.
* Comparison instructions always return at least one of
* these flags set.
*/
tmp &= ~(FPSCR_TRAP | FPSCR_IOS | FPSCR_OFS | FPSCR_UFS |
FPSCR_IXS | FPSCR_HIS | FPSCR_IOC | FPSCR_OFC |
FPSCR_UFC | FPSCR_IXC | FPSCR_HIC);
tmp |= exc;
ctf(FPSCR, tmp);
}
/*
* F64 support code initialisation.
*/
static int __init ucf64_init(void)
{
ctf(FPSCR, 0x0); /* FPSCR_UFE | FPSCR_NDE perhaps better */
printk(KERN_INFO "Enable UniCore-F64 support.\n");
return 0;
}
late_initcall(ucf64_init);
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