1 /*
2 * linux/arch/unicore32/kernel/fpu-ucf64.c
3 *
4 * Code specific to PKUnity SoC and UniCore ISA
5 *
6 * Copyright (C) 2001-2010 GUAN Xue-tao
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12 #include <linux/module.h>
13 #include <linux/types.h>
14 #include <linux/kernel.h>
15 #include <linux/signal.h>
16 #include <linux/sched/signal.h>
17 #include <linux/init.h>
18
19 #include <asm/fpu-ucf64.h>
20
21 /*
22 * A special flag to tell the normalisation code not to normalise.
23 */
24 #define F64_NAN_FLAG 0x100
25
26 /*
27 * A bit pattern used to indicate the initial (unset) value of the
28 * exception mask, in case nothing handles an instruction. This
29 * doesn't include the NAN flag, which get masked out before
30 * we check for an error.
31 */
32 #define F64_EXCEPTION_ERROR ((u32)-1 & ~F64_NAN_FLAG)
33
34 /*
35 * Since we aren't building with -mfpu=f64, we need to code
36 * these instructions using their MRC/MCR equivalents.
37 */
38 #define f64reg(_f64_) #_f64_
39
40 #define cff(_f64_) ({ \
41 u32 __v; \
42 asm("cff %0, " f64reg(_f64_) "@ fmrx %0, " #_f64_ \
43 : "=r" (__v) : : "cc"); \
44 __v; \
45 })
46
47 #define ctf(_f64_, _var_) \
48 asm("ctf %0, " f64reg(_f64_) "@ fmxr " #_f64_ ", %0" \
49 : : "r" (_var_) : "cc")
50
51 /*
52 * Raise a SIGFPE for the current process.
53 * sicode describes the signal being raised.
54 */
ucf64_raise_sigfpe(struct pt_regs * regs)55 void ucf64_raise_sigfpe(struct pt_regs *regs)
56 {
57 siginfo_t info;
58
59 clear_siginfo(&info);
60
61 info.si_signo = SIGFPE;
62 info.si_code = FPE_FLTUNK;
63 info.si_addr = (void __user *)(instruction_pointer(regs) - 4);
64
65 /*
66 * This is the same as NWFPE, because it's not clear what
67 * this is used for
68 */
69 current->thread.error_code = 0;
70 current->thread.trap_no = 6;
71
72 send_sig_info(SIGFPE, &info, current);
73 }
74
75 /*
76 * Handle exceptions of UniCore-F64.
77 */
ucf64_exchandler(u32 inst,u32 fpexc,struct pt_regs * regs)78 void ucf64_exchandler(u32 inst, u32 fpexc, struct pt_regs *regs)
79 {
80 u32 tmp = fpexc;
81 u32 exc = F64_EXCEPTION_ERROR & fpexc;
82
83 pr_debug("UniCore-F64: instruction %08x fpscr %08x\n",
84 inst, fpexc);
85
86 if (exc & FPSCR_CMPINSTR_BIT) {
87 if (exc & FPSCR_CON)
88 tmp |= FPSCR_CON;
89 else
90 tmp &= ~(FPSCR_CON);
91 exc &= ~(FPSCR_CMPINSTR_BIT | FPSCR_CON);
92 } else {
93 pr_debug("UniCore-F64 Error: unhandled exceptions\n");
94 pr_debug("UniCore-F64 FPSCR 0x%08x INST 0x%08x\n",
95 cff(FPSCR), inst);
96
97 ucf64_raise_sigfpe(regs);
98 return;
99 }
100
101 /*
102 * Update the FPSCR with the additional exception flags.
103 * Comparison instructions always return at least one of
104 * these flags set.
105 */
106 tmp &= ~(FPSCR_TRAP | FPSCR_IOS | FPSCR_OFS | FPSCR_UFS |
107 FPSCR_IXS | FPSCR_HIS | FPSCR_IOC | FPSCR_OFC |
108 FPSCR_UFC | FPSCR_IXC | FPSCR_HIC);
109
110 tmp |= exc;
111 ctf(FPSCR, tmp);
112 }
113
114 /*
115 * F64 support code initialisation.
116 */
ucf64_init(void)117 static int __init ucf64_init(void)
118 {
119 ctf(FPSCR, 0x0); /* FPSCR_UFE | FPSCR_NDE perhaps better */
120
121 printk(KERN_INFO "Enable UniCore-F64 support.\n");
122
123 return 0;
124 }
125
126 late_initcall(ucf64_init);
127
