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TOMOYO Linux Cross Reference
Linux/tools/testing/selftests/powerpc/tm/tm-unavailable.c

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  1 /*
  2  * Copyright 2017, Gustavo Romero, Breno Leitao, Cyril Bur, IBM Corp.
  3  * Licensed under GPLv2.
  4  *
  5  * Force FP, VEC and VSX unavailable exception during transaction in all
  6  * possible scenarios regarding the MSR.FP and MSR.VEC state, e.g. when FP
  7  * is enable and VEC is disable, when FP is disable and VEC is enable, and
  8  * so on. Then we check if the restored state is correctly set for the
  9  * FP and VEC registers to the previous state we set just before we entered
 10  * in TM, i.e. we check if it corrupts somehow the recheckpointed FP and
 11  * VEC/Altivec registers on abortion due to an unavailable exception in TM.
 12  * N.B. In this test we do not test all the FP/Altivec/VSX registers for
 13  * corruption, but only for registers vs0 and vs32, which are respectively
 14  * representatives of FP and VEC/Altivec reg sets.
 15  */
 16 
 17 #define _GNU_SOURCE
 18 #include <error.h>
 19 #include <stdio.h>
 20 #include <stdlib.h>
 21 #include <unistd.h>
 22 #include <inttypes.h>
 23 #include <stdbool.h>
 24 #include <pthread.h>
 25 #include <sched.h>
 26 
 27 #include "tm.h"
 28 
 29 #define DEBUG 0
 30 
 31 /* Unavailable exceptions to test in HTM */
 32 #define FP_UNA_EXCEPTION        0
 33 #define VEC_UNA_EXCEPTION       1
 34 #define VSX_UNA_EXCEPTION       2
 35 
 36 #define NUM_EXCEPTIONS          3
 37 #define err_at_line(status, errnum, format, ...) \
 38         error_at_line(status, errnum,  __FILE__, __LINE__, format ##__VA_ARGS__)
 39 
 40 #define pr_warn(code, format, ...) err_at_line(0, code, format, ##__VA_ARGS__)
 41 #define pr_err(code, format, ...) err_at_line(1, code, format, ##__VA_ARGS__)
 42 
 43 struct Flags {
 44         int touch_fp;
 45         int touch_vec;
 46         int result;
 47         int exception;
 48 } flags;
 49 
 50 bool expecting_failure(void)
 51 {
 52         if (flags.touch_fp && flags.exception == FP_UNA_EXCEPTION)
 53                 return false;
 54 
 55         if (flags.touch_vec && flags.exception == VEC_UNA_EXCEPTION)
 56                 return false;
 57 
 58         /*
 59          * If both FP and VEC are touched it does not mean that touching VSX
 60          * won't raise an exception. However since FP and VEC state are already
 61          * correctly loaded, the transaction is not aborted (i.e.
 62          * treclaimed/trecheckpointed) and MSR.VSX is just set as 1, so a TM
 63          * failure is not expected also in this case.
 64          */
 65         if ((flags.touch_fp && flags.touch_vec) &&
 66              flags.exception == VSX_UNA_EXCEPTION)
 67                 return false;
 68 
 69         return true;
 70 }
 71 
 72 /* Check if failure occurred whilst in transaction. */
 73 bool is_failure(uint64_t condition_reg)
 74 {
 75         /*
 76          * When failure handling occurs, CR0 is set to 0b1010 (0xa). Otherwise
 77          * transaction completes without failure and hence reaches out 'tend.'
 78          * that sets CR0 to 0b0100 (0x4).
 79          */
 80         return ((condition_reg >> 28) & 0xa) == 0xa;
 81 }
 82 
 83 void *tm_una_ping(void *input)
 84 {
 85 
 86         /*
 87          * Expected values for vs0 and vs32 after a TM failure. They must never
 88          * change, otherwise they got corrupted.
 89          */
 90         uint64_t high_vs0 = 0x5555555555555555;
 91         uint64_t low_vs0 = 0xffffffffffffffff;
 92         uint64_t high_vs32 = 0x5555555555555555;
 93         uint64_t low_vs32 = 0xffffffffffffffff;
 94 
 95         /* Counter for busy wait */
 96         uint64_t counter = 0x1ff000000;
 97 
 98         /*
 99          * Variable to keep a copy of CR register content taken just after we
100          * leave the transactional state.
101          */
102         uint64_t cr_ = 0;
103 
104         /*
105          * Wait a bit so thread can get its name "ping". This is not important
106          * to reproduce the issue but it's nice to have for systemtap debugging.
107          */
108         if (DEBUG)
109                 sleep(1);
110 
111         printf("If MSR.FP=%d MSR.VEC=%d: ", flags.touch_fp, flags.touch_vec);
112 
113         if (flags.exception != FP_UNA_EXCEPTION &&
114             flags.exception != VEC_UNA_EXCEPTION &&
115             flags.exception != VSX_UNA_EXCEPTION) {
116                 printf("No valid exception specified to test.\n");
117                 return NULL;
118         }
119 
120         asm (
121                 /* Prepare to merge low and high. */
122                 "       mtvsrd          33, %[high_vs0]         ;"
123                 "       mtvsrd          34, %[low_vs0]          ;"
124 
125                 /*
126                  * Adjust VS0 expected value after an TM failure,
127                  * i.e. vs0 = 0x5555555555555555555FFFFFFFFFFFFFFFF
128                  */
129                 "       xxmrghd         0, 33, 34               ;"
130 
131                 /*
132                  * Adjust VS32 expected value after an TM failure,
133                  * i.e. vs32 = 0x5555555555555555555FFFFFFFFFFFFFFFF
134                  */
135                 "       xxmrghd         32, 33, 34              ;"
136 
137                 /*
138                  * Wait an amount of context switches so load_fp and load_vec
139                  * overflow and MSR.FP, MSR.VEC, and MSR.VSX become zero (off).
140                  */
141                 "       mtctr           %[counter]              ;"
142 
143                 /* Decrement CTR branch if CTR non zero. */
144                 "1:     bdnz 1b                                 ;"
145 
146                 /*
147                  * Check if we want to touch FP prior to the test in order
148                  * to set MSR.FP = 1 before provoking an unavailable
149                  * exception in TM.
150                  */
151                 "       cmpldi          %[touch_fp], 0          ;"
152                 "       beq             no_fp                   ;"
153                 "       fadd            10, 10, 10              ;"
154                 "no_fp:                                         ;"
155 
156                 /*
157                  * Check if we want to touch VEC prior to the test in order
158                  * to set MSR.VEC = 1 before provoking an unavailable
159                  * exception in TM.
160                  */
161                 "       cmpldi          %[touch_vec], 0         ;"
162                 "       beq             no_vec                  ;"
163                 "       vaddcuw         10, 10, 10              ;"
164                 "no_vec:                                        ;"
165 
166                 /*
167                  * Perhaps it would be a better idea to do the
168                  * compares outside transactional context and simply
169                  * duplicate code.
170                  */
171                 "       tbegin.                                 ;"
172                 "       beq             trans_fail              ;"
173 
174                 /* Do we do FP Unavailable? */
175                 "       cmpldi          %[exception], %[ex_fp]  ;"
176                 "       bne             1f                      ;"
177                 "       fadd            10, 10, 10              ;"
178                 "       b               done                    ;"
179 
180                 /* Do we do VEC Unavailable? */
181                 "1:     cmpldi          %[exception], %[ex_vec] ;"
182                 "       bne             2f                      ;"
183                 "       vaddcuw         10, 10, 10              ;"
184                 "       b               done                    ;"
185 
186                 /*
187                  * Not FP or VEC, therefore VSX. Ensure this
188                  * instruction always generates a VSX Unavailable.
189                  * ISA 3.0 is tricky here.
190                  * (xxmrghd will on ISA 2.07 and ISA 3.0)
191                  */
192                 "2:     xxmrghd         10, 10, 10              ;"
193 
194                 "done:  tend. ;"
195 
196                 "trans_fail: ;"
197 
198                 /* Give values back to C. */
199                 "       mfvsrd          %[high_vs0], 0          ;"
200                 "       xxsldwi         3, 0, 0, 2              ;"
201                 "       mfvsrd          %[low_vs0], 3           ;"
202                 "       mfvsrd          %[high_vs32], 32        ;"
203                 "       xxsldwi         3, 32, 32, 2            ;"
204                 "       mfvsrd          %[low_vs32], 3          ;"
205 
206                 /* Give CR back to C so that it can check what happened. */
207                 "       mfcr            %[cr_]          ;"
208 
209                 : [high_vs0]  "+r" (high_vs0),
210                   [low_vs0]   "+r" (low_vs0),
211                   [high_vs32] "=r" (high_vs32),
212                   [low_vs32]  "=r" (low_vs32),
213                   [cr_]       "+r" (cr_)
214                 : [touch_fp]  "r"  (flags.touch_fp),
215                   [touch_vec] "r"  (flags.touch_vec),
216                   [exception] "r"  (flags.exception),
217                   [ex_fp]     "i"  (FP_UNA_EXCEPTION),
218                   [ex_vec]    "i"  (VEC_UNA_EXCEPTION),
219                   [ex_vsx]    "i"  (VSX_UNA_EXCEPTION),
220                   [counter]   "r"  (counter)
221 
222                 : "cr0", "ctr", "v10", "vs0", "vs10", "vs3", "vs32", "vs33",
223                   "vs34", "fr10"
224 
225                 );
226 
227         /*
228          * Check if we were expecting a failure and it did not occur by checking
229          * CR0 state just after we leave the transaction. Either way we check if
230          * vs0 or vs32 got corrupted.
231          */
232         if (expecting_failure() && !is_failure(cr_)) {
233                 printf("\n\tExpecting the transaction to fail, %s",
234                         "but it didn't\n\t");
235                 flags.result++;
236         }
237 
238         /* Check if we were not expecting a failure and a it occurred. */
239         if (!expecting_failure() && is_failure(cr_) &&
240             !failure_is_reschedule()) {
241                 printf("\n\tUnexpected transaction failure 0x%02lx\n\t",
242                         failure_code());
243                 return (void *) -1;
244         }
245 
246         /*
247          * Check if TM failed due to the cause we were expecting. 0xda is a
248          * TM_CAUSE_FAC_UNAV cause, otherwise it's an unexpected cause, unless
249          * it was caused by a reschedule.
250          */
251         if (is_failure(cr_) && !failure_is_unavailable() &&
252             !failure_is_reschedule()) {
253                 printf("\n\tUnexpected failure cause 0x%02lx\n\t",
254                         failure_code());
255                 return (void *) -1;
256         }
257 
258         /* 0x4 is a success and 0xa is a fail. See comment in is_failure(). */
259         if (DEBUG)
260                 printf("CR0: 0x%1lx ", cr_ >> 28);
261 
262         /* Check FP (vs0) for the expected value. */
263         if (high_vs0 != 0x5555555555555555 || low_vs0 != 0xFFFFFFFFFFFFFFFF) {
264                 printf("FP corrupted!");
265                         printf("  high = %#16" PRIx64 "  low = %#16" PRIx64 " ",
266                                 high_vs0, low_vs0);
267                 flags.result++;
268         } else
269                 printf("FP ok ");
270 
271         /* Check VEC (vs32) for the expected value. */
272         if (high_vs32 != 0x5555555555555555 || low_vs32 != 0xFFFFFFFFFFFFFFFF) {
273                 printf("VEC corrupted!");
274                         printf("  high = %#16" PRIx64 "  low = %#16" PRIx64,
275                                 high_vs32, low_vs32);
276                 flags.result++;
277         } else
278                 printf("VEC ok");
279 
280         putchar('\n');
281 
282         return NULL;
283 }
284 
285 /* Thread to force context switch */
286 void *tm_una_pong(void *not_used)
287 {
288         /* Wait thread get its name "pong". */
289         if (DEBUG)
290                 sleep(1);
291 
292         /* Classed as an interactive-like thread. */
293         while (1)
294                 sched_yield();
295 }
296 
297 /* Function that creates a thread and launches the "ping" task. */
298 void test_fp_vec(int fp, int vec, pthread_attr_t *attr)
299 {
300         int retries = 2;
301         void *ret_value;
302         pthread_t t0;
303 
304         flags.touch_fp = fp;
305         flags.touch_vec = vec;
306 
307         /*
308          * Without luck it's possible that the transaction is aborted not due to
309          * the unavailable exception caught in the middle as we expect but also,
310          * for instance, due to a context switch or due to a KVM reschedule (if
311          * it's running on a VM). Thus we try a few times before giving up,
312          * checking if the failure cause is the one we expect.
313          */
314         do {
315                 int rc;
316 
317                 /* Bind to CPU 0, as specified in 'attr'. */
318                 rc = pthread_create(&t0, attr, tm_una_ping, (void *) &flags);
319                 if (rc)
320                         pr_err(rc, "pthread_create()");
321                 rc = pthread_setname_np(t0, "tm_una_ping");
322                 if (rc)
323                         pr_warn(rc, "pthread_setname_np");
324                 rc = pthread_join(t0, &ret_value);
325                 if (rc)
326                         pr_err(rc, "pthread_join");
327 
328                 retries--;
329         } while (ret_value != NULL && retries);
330 
331         if (!retries) {
332                 flags.result = 1;
333                 if (DEBUG)
334                         printf("All transactions failed unexpectedly\n");
335 
336         }
337 }
338 
339 int tm_unavailable_test(void)
340 {
341         int rc, exception; /* FP = 0, VEC = 1, VSX = 2 */
342         pthread_t t1;
343         pthread_attr_t attr;
344         cpu_set_t cpuset;
345 
346         SKIP_IF(!have_htm());
347 
348         /* Set only CPU 0 in the mask. Both threads will be bound to CPU 0. */
349         CPU_ZERO(&cpuset);
350         CPU_SET(0, &cpuset);
351 
352         /* Init pthread attribute. */
353         rc = pthread_attr_init(&attr);
354         if (rc)
355                 pr_err(rc, "pthread_attr_init()");
356 
357         /* Set CPU 0 mask into the pthread attribute. */
358         rc = pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
359         if (rc)
360                 pr_err(rc, "pthread_attr_setaffinity_np()");
361 
362         rc = pthread_create(&t1, &attr /* Bind to CPU 0 */, tm_una_pong, NULL);
363         if (rc)
364                 pr_err(rc, "pthread_create()");
365 
366         /* Name it for systemtap convenience */
367         rc = pthread_setname_np(t1, "tm_una_pong");
368         if (rc)
369                 pr_warn(rc, "pthread_create()");
370 
371         flags.result = 0;
372 
373         for (exception = 0; exception < NUM_EXCEPTIONS; exception++) {
374                 printf("Checking if FP/VEC registers are sane after");
375 
376                 if (exception == FP_UNA_EXCEPTION)
377                         printf(" a FP unavailable exception...\n");
378 
379                 else if (exception == VEC_UNA_EXCEPTION)
380                         printf(" a VEC unavailable exception...\n");
381 
382                 else
383                         printf(" a VSX unavailable exception...\n");
384 
385                 flags.exception = exception;
386 
387                 test_fp_vec(0, 0, &attr);
388                 test_fp_vec(1, 0, &attr);
389                 test_fp_vec(0, 1, &attr);
390                 test_fp_vec(1, 1, &attr);
391 
392         }
393 
394         if (flags.result > 0) {
395                 printf("result: failed!\n");
396                 exit(1);
397         } else {
398                 printf("result: success\n");
399                 exit(0);
400         }
401 }
402 
403 int main(int argc, char **argv)
404 {
405         test_harness_set_timeout(220);
406         return test_harness(tm_unavailable_test, "tm_unavailable_test");
407 }
408 

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