xref: /openbmc/linux/arch/parisc/math-emu/driver.c (revision 0c6dfa75)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Linux/PA-RISC Project (http://www.parisc-linux.org/)
4  *
5  * Floating-point emulation code
6  *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
7  */
8 /*
9  *  linux/arch/math-emu/driver.c.c
10  *
11  *	decodes and dispatches unimplemented FPU instructions
12  *
13  *  Copyright (C) 1999, 2000  Philipp Rumpf <prumpf@tux.org>
14  *  Copyright (C) 2001	      Hewlett-Packard <bame@debian.org>
15  */
16 
17 #include <linux/sched/signal.h>
18 
19 #include "float.h"
20 #include "math-emu.h"
21 
22 
23 #define fptpos 31
24 #define fpr1pos 10
25 #define extru(r,pos,len) (((r) >> (31-(pos))) & (( 1 << (len)) - 1))
26 
27 #define FPUDEBUG 0
28 
29 /* Format of the floating-point exception registers. */
30 struct exc_reg {
31 	unsigned int exception : 6;
32 	unsigned int ei : 26;
33 };
34 
35 /* Macros for grabbing bits of the instruction format from the 'ei'
36    field above. */
37 /* Major opcode 0c and 0e */
38 #define FP0CE_UID(i) (((i) >> 6) & 3)
39 #define FP0CE_CLASS(i) (((i) >> 9) & 3)
40 #define FP0CE_SUBOP(i) (((i) >> 13) & 7)
41 #define FP0CE_SUBOP1(i) (((i) >> 15) & 7) /* Class 1 subopcode */
42 #define FP0C_FORMAT(i) (((i) >> 11) & 3)
43 #define FP0E_FORMAT(i) (((i) >> 11) & 1)
44 
45 /* Major opcode 0c, uid 2 (performance monitoring) */
46 #define FPPM_SUBOP(i) (((i) >> 9) & 0x1f)
47 
48 /* Major opcode 2e (fused operations).   */
49 #define FP2E_SUBOP(i)  (((i) >> 5) & 1)
50 #define FP2E_FORMAT(i) (((i) >> 11) & 1)
51 
52 /* Major opcode 26 (FMPYSUB) */
53 /* Major opcode 06 (FMPYADD) */
54 #define FPx6_FORMAT(i) ((i) & 0x1f)
55 
56 /* Flags and enable bits of the status word. */
57 #define FPSW_FLAGS(w) ((w) >> 27)
58 #define FPSW_ENABLE(w) ((w) & 0x1f)
59 #define FPSW_V (1<<4)
60 #define FPSW_Z (1<<3)
61 #define FPSW_O (1<<2)
62 #define FPSW_U (1<<1)
63 #define FPSW_I (1<<0)
64 
65 /* Handle a floating point exception.  Return zero if the faulting
66    instruction can be completed successfully. */
67 int
68 handle_fpe(struct pt_regs *regs)
69 {
70 	extern void printbinary(unsigned long x, int nbits);
71 	unsigned int orig_sw, sw;
72 	int signalcode;
73 	/* need an intermediate copy of float regs because FPU emulation
74 	 * code expects an artificial last entry which contains zero
75 	 *
76 	 * also, the passed in fr registers contain one word that defines
77 	 * the fpu type. the fpu type information is constructed
78 	 * inside the emulation code
79 	 */
80 	__u64 frcopy[36];
81 
82 	memcpy(frcopy, regs->fr, sizeof regs->fr);
83 	frcopy[32] = 0;
84 
85 	memcpy(&orig_sw, frcopy, sizeof(orig_sw));
86 
87 	if (FPUDEBUG) {
88 		printk(KERN_DEBUG "FP VZOUICxxxxCQCQCQCQCQCRMxxTDVZOUI ->\n   ");
89 		printbinary(orig_sw, 32);
90 		printk(KERN_DEBUG "\n");
91 	}
92 
93 	signalcode = decode_fpu(frcopy, 0x666);
94 
95 	/* Status word = FR0L. */
96 	memcpy(&sw, frcopy, sizeof(sw));
97 	if (FPUDEBUG) {
98 		printk(KERN_DEBUG "VZOUICxxxxCQCQCQCQCQCRMxxTDVZOUI decode_fpu returns %d|0x%x\n",
99 			signalcode >> 24, signalcode & 0xffffff);
100 		printbinary(sw, 32);
101 		printk(KERN_DEBUG "\n");
102 	}
103 
104 	memcpy(regs->fr, frcopy, sizeof regs->fr);
105 	if (signalcode != 0) {
106 	    force_sig_fault(signalcode >> 24, signalcode & 0xffffff,
107 			    (void __user *) regs->iaoq[0]);
108 	    return -1;
109 	}
110 
111 	return signalcode ? -1 : 0;
112 }
113