1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Copyright (C) 2003, 2004, 2007 Maciej W. Rozycki |
4 | */ |
5 | #include <linux/context_tracking.h> |
6 | #include <linux/init.h> |
7 | #include <linux/kernel.h> |
8 | #include <linux/ptrace.h> |
9 | #include <linux/stddef.h> |
10 | |
11 | #include <asm/bugs.h> |
12 | #include <asm/compiler.h> |
13 | #include <asm/cpu.h> |
14 | #include <asm/fpu.h> |
15 | #include <asm/mipsregs.h> |
16 | #include <asm/setup.h> |
17 | |
18 | static char bug64hit[] __initdata = |
19 | "reliable operation impossible!\n%s" ; |
20 | static char nowar[] __initdata = |
21 | "Please report to <linux-mips@vger.kernel.org>." ; |
22 | static char r4kwar[] __initdata = |
23 | "Enable CPU_R4000_WORKAROUNDS to rectify." ; |
24 | static char daddiwar[] __initdata = |
25 | "Enable CPU_DADDI_WORKAROUNDS to rectify." ; |
26 | |
27 | static __always_inline __init |
28 | void align_mod(const int align, const int mod) |
29 | { |
30 | asm volatile( |
31 | ".set push\n\t" |
32 | ".set noreorder\n\t" |
33 | ".balign %0\n\t" |
34 | ".rept %1\n\t" |
35 | "nop\n\t" |
36 | ".endr\n\t" |
37 | ".set pop" |
38 | : |
39 | : "n" (align), "n" (mod)); |
40 | } |
41 | |
42 | static __always_inline __init |
43 | void mult_sh_align_mod(long *v1, long *v2, long *w, |
44 | const int align, const int mod) |
45 | { |
46 | unsigned long flags; |
47 | int m1, m2; |
48 | long p, s, lv1, lv2, lw; |
49 | |
50 | /* |
51 | * We want the multiply and the shift to be isolated from the |
52 | * rest of the code to disable gcc optimizations. Hence the |
53 | * asm statements that execute nothing, but make gcc not know |
54 | * what the values of m1, m2 and s are and what lv2 and p are |
55 | * used for. |
56 | */ |
57 | |
58 | local_irq_save(flags); |
59 | /* |
60 | * The following code leads to a wrong result of the first |
61 | * dsll32 when executed on R4000 rev. 2.2 or 3.0 (PRId |
62 | * 00000422 or 00000430, respectively). |
63 | * |
64 | * See "MIPS R4000PC/SC Errata, Processor Revision 2.2 and |
65 | * 3.0" by MIPS Technologies, Inc., errata #16 and #28 for |
66 | * details. I got no permission to duplicate them here, |
67 | * sigh... --macro |
68 | */ |
69 | asm volatile( |
70 | "" |
71 | : "=r" (m1), "=r" (m2), "=r" (s) |
72 | : "0" (5), "1" (8), "2" (5)); |
73 | align_mod(align, mod); |
74 | /* |
75 | * The trailing nop is needed to fulfill the two-instruction |
76 | * requirement between reading hi/lo and staring a mult/div. |
77 | * Leaving it out may cause gas insert a nop itself breaking |
78 | * the desired alignment of the next chunk. |
79 | */ |
80 | asm volatile( |
81 | ".set push\n\t" |
82 | ".set noat\n\t" |
83 | ".set noreorder\n\t" |
84 | ".set nomacro\n\t" |
85 | "mult %2, %3\n\t" |
86 | "dsll32 %0, %4, %5\n\t" |
87 | "mflo $0\n\t" |
88 | "dsll32 %1, %4, %5\n\t" |
89 | "nop\n\t" |
90 | ".set pop" |
91 | : "=&r" (lv1), "=r" (lw) |
92 | : "r" (m1), "r" (m2), "r" (s), "I" (0) |
93 | : "hi" , "lo" , "$0" ); |
94 | /* We have to use single integers for m1 and m2 and a double |
95 | * one for p to be sure the mulsidi3 gcc's RTL multiplication |
96 | * instruction has the workaround applied. Older versions of |
97 | * gcc have correct umulsi3 and mulsi3, but other |
98 | * multiplication variants lack the workaround. |
99 | */ |
100 | asm volatile( |
101 | "" |
102 | : "=r" (m1), "=r" (m2), "=r" (s) |
103 | : "0" (m1), "1" (m2), "2" (s)); |
104 | align_mod(align, mod); |
105 | p = m1 * m2; |
106 | lv2 = s << 32; |
107 | asm volatile( |
108 | "" |
109 | : "=r" (lv2) |
110 | : "0" (lv2), "r" (p)); |
111 | local_irq_restore(flags); |
112 | |
113 | *v1 = lv1; |
114 | *v2 = lv2; |
115 | *w = lw; |
116 | } |
117 | |
118 | static __always_inline __init void check_mult_sh(void) |
119 | { |
120 | long v1[8], v2[8], w[8]; |
121 | int bug, fix, i; |
122 | |
123 | printk("Checking for the multiply/shift bug... " ); |
124 | |
125 | /* |
126 | * Testing discovered false negatives for certain code offsets |
127 | * into cache lines. Hence we test all possible offsets for |
128 | * the worst assumption of an R4000 I-cache line width of 32 |
129 | * bytes. |
130 | * |
131 | * We can't use a loop as alignment directives need to be |
132 | * immediates. |
133 | */ |
134 | mult_sh_align_mod(v1: &v1[0], v2: &v2[0], w: &w[0], align: 32, mod: 0); |
135 | mult_sh_align_mod(v1: &v1[1], v2: &v2[1], w: &w[1], align: 32, mod: 1); |
136 | mult_sh_align_mod(v1: &v1[2], v2: &v2[2], w: &w[2], align: 32, mod: 2); |
137 | mult_sh_align_mod(v1: &v1[3], v2: &v2[3], w: &w[3], align: 32, mod: 3); |
138 | mult_sh_align_mod(v1: &v1[4], v2: &v2[4], w: &w[4], align: 32, mod: 4); |
139 | mult_sh_align_mod(v1: &v1[5], v2: &v2[5], w: &w[5], align: 32, mod: 5); |
140 | mult_sh_align_mod(v1: &v1[6], v2: &v2[6], w: &w[6], align: 32, mod: 6); |
141 | mult_sh_align_mod(v1: &v1[7], v2: &v2[7], w: &w[7], align: 32, mod: 7); |
142 | |
143 | bug = 0; |
144 | for (i = 0; i < 8; i++) |
145 | if (v1[i] != w[i]) |
146 | bug = 1; |
147 | |
148 | if (bug == 0) { |
149 | pr_cont("no.\n" ); |
150 | return; |
151 | } |
152 | |
153 | pr_cont("yes, workaround... " ); |
154 | |
155 | fix = 1; |
156 | for (i = 0; i < 8; i++) |
157 | if (v2[i] != w[i]) |
158 | fix = 0; |
159 | |
160 | if (fix == 1) { |
161 | pr_cont("yes.\n" ); |
162 | return; |
163 | } |
164 | |
165 | pr_cont("no.\n" ); |
166 | panic(fmt: bug64hit, |
167 | IS_ENABLED(CONFIG_CPU_R4000_WORKAROUNDS) ? nowar : r4kwar); |
168 | } |
169 | |
170 | static volatile int daddi_ov; |
171 | |
172 | asmlinkage void __init do_daddi_ov(struct pt_regs *regs) |
173 | { |
174 | enum ctx_state prev_state; |
175 | |
176 | prev_state = exception_enter(); |
177 | daddi_ov = 1; |
178 | regs->cp0_epc += 4; |
179 | exception_exit(prev_ctx: prev_state); |
180 | } |
181 | |
182 | static __init void check_daddi(void) |
183 | { |
184 | extern asmlinkage void handle_daddi_ov(void); |
185 | unsigned long flags; |
186 | void *handler; |
187 | long v, tmp; |
188 | |
189 | printk("Checking for the daddi bug... " ); |
190 | |
191 | local_irq_save(flags); |
192 | handler = set_except_vector(EXCCODE_OV, handle_daddi_ov); |
193 | /* |
194 | * The following code fails to trigger an overflow exception |
195 | * when executed on R4000 rev. 2.2 or 3.0 (PRId 00000422 or |
196 | * 00000430, respectively). |
197 | * |
198 | * See "MIPS R4000PC/SC Errata, Processor Revision 2.2 and |
199 | * 3.0" by MIPS Technologies, Inc., erratum #23 for details. |
200 | * I got no permission to duplicate it here, sigh... --macro |
201 | */ |
202 | asm volatile( |
203 | ".set push\n\t" |
204 | ".set noat\n\t" |
205 | ".set noreorder\n\t" |
206 | ".set nomacro\n\t" |
207 | "addiu %1, $0, %2\n\t" |
208 | "dsrl %1, %1, 1\n\t" |
209 | #ifdef HAVE_AS_SET_DADDI |
210 | ".set daddi\n\t" |
211 | #endif |
212 | "daddi %0, %1, %3\n\t" |
213 | ".set pop" |
214 | : "=r" (v), "=&r" (tmp) |
215 | : "I" (0xffffffffffffdb9aUL), "I" (0x1234)); |
216 | set_except_vector(EXCCODE_OV, handler); |
217 | local_irq_restore(flags); |
218 | |
219 | if (daddi_ov) { |
220 | pr_cont("no.\n" ); |
221 | return; |
222 | } |
223 | |
224 | pr_cont("yes, workaround... " ); |
225 | |
226 | local_irq_save(flags); |
227 | handler = set_except_vector(EXCCODE_OV, handle_daddi_ov); |
228 | asm volatile( |
229 | "addiu %1, $0, %2\n\t" |
230 | "dsrl %1, %1, 1\n\t" |
231 | "daddi %0, %1, %3" |
232 | : "=r" (v), "=&r" (tmp) |
233 | : "I" (0xffffffffffffdb9aUL), "I" (0x1234)); |
234 | set_except_vector(EXCCODE_OV, handler); |
235 | local_irq_restore(flags); |
236 | |
237 | if (daddi_ov) { |
238 | pr_cont("yes.\n" ); |
239 | return; |
240 | } |
241 | |
242 | pr_cont("no.\n" ); |
243 | panic(fmt: bug64hit, |
244 | IS_ENABLED(CONFIG_CPU_DADDI_WORKAROUNDS) ? nowar : daddiwar); |
245 | } |
246 | |
247 | int daddiu_bug = -1; |
248 | |
249 | static __init void check_daddiu(void) |
250 | { |
251 | long v, w, tmp; |
252 | |
253 | printk("Checking for the daddiu bug... " ); |
254 | |
255 | /* |
256 | * The following code leads to a wrong result of daddiu when |
257 | * executed on R4400 rev. 1.0 (PRId 00000440). |
258 | * |
259 | * See "MIPS R4400PC/SC Errata, Processor Revision 1.0" by |
260 | * MIPS Technologies, Inc., erratum #7 for details. |
261 | * |
262 | * According to "MIPS R4000PC/SC Errata, Processor Revision |
263 | * 2.2 and 3.0" by MIPS Technologies, Inc., erratum #41 this |
264 | * problem affects R4000 rev. 2.2 and 3.0 (PRId 00000422 and |
265 | * 00000430, respectively), too. Testing failed to trigger it |
266 | * so far. |
267 | * |
268 | * I got no permission to duplicate the errata here, sigh... |
269 | * --macro |
270 | */ |
271 | asm volatile( |
272 | ".set push\n\t" |
273 | ".set noat\n\t" |
274 | ".set noreorder\n\t" |
275 | ".set nomacro\n\t" |
276 | "addiu %2, $0, %3\n\t" |
277 | "dsrl %2, %2, 1\n\t" |
278 | #ifdef HAVE_AS_SET_DADDI |
279 | ".set daddi\n\t" |
280 | #endif |
281 | "daddiu %0, %2, %4\n\t" |
282 | "addiu %1, $0, %4\n\t" |
283 | "daddu %1, %2\n\t" |
284 | ".set pop" |
285 | : "=&r" (v), "=&r" (w), "=&r" (tmp) |
286 | : "I" (0xffffffffffffdb9aUL), "I" (0x1234)); |
287 | |
288 | daddiu_bug = v != w; |
289 | |
290 | if (!daddiu_bug) { |
291 | pr_cont("no.\n" ); |
292 | return; |
293 | } |
294 | |
295 | pr_cont("yes, workaround... " ); |
296 | |
297 | asm volatile( |
298 | "addiu %2, $0, %3\n\t" |
299 | "dsrl %2, %2, 1\n\t" |
300 | "daddiu %0, %2, %4\n\t" |
301 | "addiu %1, $0, %4\n\t" |
302 | "daddu %1, %2" |
303 | : "=&r" (v), "=&r" (w), "=&r" (tmp) |
304 | : "I" (0xffffffffffffdb9aUL), "I" (0x1234)); |
305 | |
306 | if (v == w) { |
307 | pr_cont("yes.\n" ); |
308 | return; |
309 | } |
310 | |
311 | pr_cont("no.\n" ); |
312 | panic(fmt: bug64hit, |
313 | IS_ENABLED(CONFIG_CPU_DADDI_WORKAROUNDS) ? nowar : daddiwar); |
314 | } |
315 | |
316 | void __init check_bugs64_early(void) |
317 | { |
318 | check_mult_sh(); |
319 | check_daddiu(); |
320 | } |
321 | |
322 | void __init check_bugs64(void) |
323 | { |
324 | check_daddi(); |
325 | } |
326 | |