1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Emulation of the "brl" instruction for IA64 processors that
4 * don't support it in hardware.
5 * Author: Stephan Zeisset, Intel Corp. <Stephan.Zeisset@intel.com>
6 *
7 * 02/22/02 D. Mosberger Clear si_flgs, si_isr, and si_imm to avoid
8 * leaking kernel bits.
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/sched/signal.h>
13 #include <linux/uaccess.h>
14 #include <asm/processor.h>
15
16 extern char ia64_set_b1, ia64_set_b2, ia64_set_b3, ia64_set_b4, ia64_set_b5;
17
18 struct illegal_op_return {
19 unsigned long fkt, arg1, arg2, arg3;
20 };
21
22 /*
23 * The unimplemented bits of a virtual address must be set
24 * to the value of the most significant implemented bit.
25 * unimpl_va_mask includes all unimplemented bits and
26 * the most significant implemented bit, so the result
27 * of an and operation with the mask must be all 0's
28 * or all 1's for the address to be valid.
29 */
30 #define unimplemented_virtual_address(va) ( \
31 ((va) & local_cpu_data->unimpl_va_mask) != 0 && \
32 ((va) & local_cpu_data->unimpl_va_mask) != local_cpu_data->unimpl_va_mask \
33 )
34
35 /*
36 * The unimplemented bits of a physical address must be 0.
37 * unimpl_pa_mask includes all unimplemented bits, so the result
38 * of an and operation with the mask must be all 0's for the
39 * address to be valid.
40 */
41 #define unimplemented_physical_address(pa) ( \
42 ((pa) & local_cpu_data->unimpl_pa_mask) != 0 \
43 )
44
45 /*
46 * Handle an illegal operation fault that was caused by an
47 * unimplemented "brl" instruction.
48 * If we are not successful (e.g because the illegal operation
49 * wasn't caused by a "brl" after all), we return -1.
50 * If we are successful, we return either 0 or the address
51 * of a "fixup" function for manipulating preserved register
52 * state.
53 */
54
55 struct illegal_op_return
56 ia64_emulate_brl (struct pt_regs *regs, unsigned long ar_ec)
57 {
58 unsigned long bundle[2];
59 unsigned long opcode, btype, qp, offset, cpl;
60 unsigned long next_ip;
61 struct illegal_op_return rv;
62 long tmp_taken, unimplemented_address;
63
64 rv.fkt = (unsigned long) -1;
65
66 /*
67 * Decode the instruction bundle.
68 */
69
70 if (copy_from_user(bundle, (void *) (regs->cr_iip), sizeof(bundle)))
71 return rv;
72
73 next_ip = (unsigned long) regs->cr_iip + 16;
74
75 /* "brl" must be in slot 2. */
76 if (ia64_psr(regs)->ri != 1) return rv;
77
78 /* Must be "mlx" template */
79 if ((bundle[0] & 0x1e) != 0x4) return rv;
80
81 opcode = (bundle[1] >> 60);
82 btype = ((bundle[1] >> 29) & 0x7);
83 qp = ((bundle[1] >> 23) & 0x3f);
84 offset = ((bundle[1] & 0x0800000000000000L) << 4)
85 | ((bundle[1] & 0x00fffff000000000L) >> 32)
86 | ((bundle[1] & 0x00000000007fffffL) << 40)
87 | ((bundle[0] & 0xffff000000000000L) >> 24);
88
89 tmp_taken = regs->pr & (1L << qp);
90
91 switch(opcode) {
92
93 case 0xC:
94 /*
95 * Long Branch.
96 */
97 if (btype != 0) return rv;
98 rv.fkt = 0;
99 if (!(tmp_taken)) {
100 /*
101 * Qualifying predicate is 0.
102 * Skip instruction.
103 */
104 regs->cr_iip = next_ip;
105 ia64_psr(regs)->ri = 0;
106 return rv;
107 }
108 break;
109
110 case 0xD:
111 /*
112 * Long Call.
113 */
114 rv.fkt = 0;
115 if (!(tmp_taken)) {
116 /*
117 * Qualifying predicate is 0.
118 * Skip instruction.
119 */
120 regs->cr_iip = next_ip;
121 ia64_psr(regs)->ri = 0;
122 return rv;
123 }
124
125 /*
126 * BR[btype] = IP+16
127 */
128 switch(btype) {
129 case 0:
130 regs->b0 = next_ip;
131 break;
132 case 1:
133 rv.fkt = (unsigned long) &ia64_set_b1;
134 break;
135 case 2:
136 rv.fkt = (unsigned long) &ia64_set_b2;
137 break;
138 case 3:
139 rv.fkt = (unsigned long) &ia64_set_b3;
140 break;
141 case 4:
142 rv.fkt = (unsigned long) &ia64_set_b4;
143 break;
144 case 5:
145 rv.fkt = (unsigned long) &ia64_set_b5;
146 break;
147 case 6:
148 regs->b6 = next_ip;
149 break;
150 case 7:
151 regs->b7 = next_ip;
152 break;
153 }
154 rv.arg1 = next_ip;
155
156 /*
157 * AR[PFS].pfm = CFM
158 * AR[PFS].pec = AR[EC]
159 * AR[PFS].ppl = PSR.cpl
160 */
161 cpl = ia64_psr(regs)->cpl;
162 regs->ar_pfs = ((regs->cr_ifs & 0x3fffffffff)
163 | (ar_ec << 52) | (cpl << 62));
164
165 /*
166 * CFM.sof -= CFM.sol
167 * CFM.sol = 0
168 * CFM.sor = 0
169 * CFM.rrb.gr = 0
170 * CFM.rrb.fr = 0
171 * CFM.rrb.pr = 0
172 */
173 regs->cr_ifs = ((regs->cr_ifs & 0xffffffc00000007f)
174 - ((regs->cr_ifs >> 7) & 0x7f));
175
176 break;
177
178 default:
179 /*
180 * Unknown opcode.
181 */
182 return rv;
183
184 }
185
186 regs->cr_iip += offset;
187 ia64_psr(regs)->ri = 0;
188
189 if (ia64_psr(regs)->it == 0)
190 unimplemented_address = unimplemented_physical_address(regs->cr_iip);
191 else
192 unimplemented_address = unimplemented_virtual_address(regs->cr_iip);
193
194 if (unimplemented_address) {
195 /*
196 * The target address contains unimplemented bits.
197 */
198 printk(KERN_DEBUG "Woah! Unimplemented Instruction Address Trap!\n");
199 force_sig_fault(SIGILL, ILL_BADIADDR, (void __user *)NULL,
200 0, 0, 0);
201 } else if (ia64_psr(regs)->tb) {
202 /*
203 * Branch Tracing is enabled.
204 * Force a taken branch signal.
205 */
206 force_sig_fault(SIGTRAP, TRAP_BRANCH, (void __user *)NULL,
207 0, 0, 0);
208 } else if (ia64_psr(regs)->ss) {
209 /*
210 * Single Step is enabled.
211 * Force a trace signal.
212 */
213 force_sig_fault(SIGTRAP, TRAP_TRACE, (void __user *)NULL,
214 0, 0, 0);
215 }
216 return rv;
217 }