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mem_noshuf_exception.c (4445B)

      1 /*
      2  *  Copyright(c) 2022 Qualcomm Innovation Center, Inc. All Rights Reserved.
      3  *
      4  *  This program is free software; you can redistribute it and/or modify
      5  *  it under the terms of the GNU General Public License as published by
      6  *  the Free Software Foundation; either version 2 of the License, or
      7  *  (at your option) any later version.
      8  *
      9  *  This program is distributed in the hope that it will be useful,
     10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
     11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     12  *  GNU General Public License for more details.
     13  *
     14  *  You should have received a copy of the GNU General Public License
     15  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
     16  */
     17 
     18 /*
     19  * Test the VLIW semantics of exceptions with mem_noshuf
     20  *
     21  * When a packet has the :mem_noshuf attribute, the semantics dictate
     22  * That the load will get the data from the store if the addresses overlap.
     23  * To accomplish this, we perform the store first.  However, we have to
     24  * handle the case where the store raises an exception.  In that case, the
     25  * store should not alter the machine state.
     26  *
     27  * We test this with a mem_noshuf packet with a store to a global variable,
     28  * "should_not_change" and a load from NULL.  After the SIGSEGV is caught,
     29  * we check * that the "should_not_change" value is the same.
     30  *
     31  * We also check that a predicated load where the predicate is false doesn't
     32  * raise an exception and allows the store to happen.
     33  */
     34 
     35 #include <stdlib.h>
     36 #include <stdio.h>
     37 #include <unistd.h>
     38 #include <sys/types.h>
     39 #include <fcntl.h>
     40 #include <setjmp.h>
     41 #include <signal.h>
     42 
     43 int err;
     44 int segv_caught;
     45 
     46 #define SHOULD_NOT_CHANGE_VAL        5
     47 int should_not_change = SHOULD_NOT_CHANGE_VAL;
     48 
     49 #define OK_TO_CHANGE_VAL        13
     50 int ok_to_change = OK_TO_CHANGE_VAL;
     51 
     52 static void __check(const char *filename, int line, int x, int expect)
     53 {
     54     if (x != expect) {
     55         printf("ERROR %s:%d - %d != %d\n",
     56                filename, line, x, expect);
     57         err++;
     58     }
     59 }
     60 
     61 #define check(x, expect) __check(__FILE__, __LINE__, (x), (expect))
     62 
     63 static void __chk_error(const char *filename, int line, int ret)
     64 {
     65     if (ret < 0) {
     66         printf("ERROR %s:%d - %d\n", filename, line, ret);
     67         err++;
     68     }
     69 }
     70 
     71 #define chk_error(ret) __chk_error(__FILE__, __LINE__, (ret))
     72 
     73 jmp_buf jmp_env;
     74 
     75 static void sig_segv(int sig, siginfo_t *info, void *puc)
     76 {
     77     check(sig, SIGSEGV);
     78     segv_caught = 1;
     79     longjmp(jmp_env, 1);
     80 }
     81 
     82 int main()
     83 {
     84     struct sigaction act;
     85     int dummy32;
     86     long long dummy64;
     87     void *p;
     88 
     89     /* SIGSEGV test */
     90     act.sa_sigaction = sig_segv;
     91     sigemptyset(&act.sa_mask);
     92     act.sa_flags = SA_SIGINFO;
     93     chk_error(sigaction(SIGSEGV, &act, NULL));
     94     if (setjmp(jmp_env) == 0) {
     95         asm volatile("r18 = ##should_not_change\n\t"
     96                      "r19 = #0\n\t"
     97                      "{\n\t"
     98                      "    memw(r18) = #7\n\t"
     99                      "    %0 = memw(r19)\n\t"
    100                      "}:mem_noshuf\n\t"
    101                       : "=r"(dummy32) : : "r18", "r19", "memory");
    102     }
    103 
    104     act.sa_handler = SIG_DFL;
    105     sigemptyset(&act.sa_mask);
    106     act.sa_flags = 0;
    107     chk_error(sigaction(SIGSEGV, &act, NULL));
    108 
    109     check(segv_caught, 1);
    110     check(should_not_change, SHOULD_NOT_CHANGE_VAL);
    111 
    112     /*
    113      * Check that a predicated load where the predicate is false doesn't
    114      * raise an exception and allows the store to happen.
    115      */
    116     asm volatile("r18 = ##ok_to_change\n\t"
    117                  "r19 = #0\n\t"
    118                  "p0 = cmp.gt(r0, r0)\n\t"
    119                  "{\n\t"
    120                  "    memw(r18) = #7\n\t"
    121                  "    if (p0) %0 = memw(r19)\n\t"
    122                  "}:mem_noshuf\n\t"
    123                   : "=r"(dummy32) : : "r18", "r19", "p0", "memory");
    124 
    125     check(ok_to_change, 7);
    126 
    127     /*
    128      * Also check that the post-increment doesn't happen when the
    129      * predicate is false.
    130      */
    131     ok_to_change = OK_TO_CHANGE_VAL;
    132     p = NULL;
    133     asm volatile("r18 = ##ok_to_change\n\t"
    134                  "p0 = cmp.gt(r0, r0)\n\t"
    135                  "{\n\t"
    136                  "    memw(r18) = #9\n\t"
    137                  "    if (p0) %1 = memd(%0 ++ #8)\n\t"
    138                  "}:mem_noshuf\n\t"
    139                   : "+r"(p), "=r"(dummy64) : : "r18", "p0", "memory");
    140 
    141     check(ok_to_change, 9);
    142     check((int)p, (int)NULL);
    143 
    144     puts(err ? "FAIL" : "PASS");
    145     return err ? EXIT_FAILURE : EXIT_SUCCESS;
    146 }