tools/testing/selftests/powerpc/tm/tm-resched-dscr.c

   1 /* Test context switching to see if the DSCR SPR is correctly preserved
   2  * when within a transaction.
   3  *
   4  * Note: We assume that the DSCR has been left at the default value (0)
   5  * for all CPUs.
   6  *
   7  * Method:
   8  *
   9  * Set a value into the DSCR.
  10  *
  11  * Start a transaction, and suspend it (*).
  12  *
  13  * Hard loop checking to see if the transaction has become doomed.
  14  *
  15  * Now that we *may* have been preempted, record the DSCR and TEXASR SPRS.
  16  *
  17  * If the abort was because of a context switch, check the DSCR value.
  18  * Otherwise, try again.
  19  *
  20  * (*) If the transaction is not suspended we can't see the problem because
  21  * the transaction abort handler will restore the DSCR to it's checkpointed
  22  * value before we regain control.
  23  */
  24
  25 #include <inttypes.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <assert.h>
  29 #include <asm/tm.h>
  30
  31 #include "utils.h"
  32 #include "tm.h"
  33
  34 #define SPRN_DSCR       0x03
  35
  36 int test_body(void)
  37 {
  38         uint64_t rv, dscr1 = 1, dscr2, texasr;
  39
  40         SKIP_IF(!have_htm());
  41
  42         printf("Check DSCR TM context switch: ");
  43         fflush(stdout);
  44         for (;;) {
  45                 rv = 1;
  46                 asm __volatile__ (
  47                         /* set a known value into the DSCR */
  48                         "ld      3, %[dscr1];"
  49                         "mtspr   %[sprn_dscr], 3;"
  50
  51                         /* start and suspend a transaction */
  52                         "tbegin.;"
  53                         "beq     1f;"
  54                         "tsuspend.;"
  55
  56                         /* hard loop until the transaction becomes doomed */
  57                         "2: ;"
  58                         "tcheck 0;"
  59                         "bc      4, 0, 2b;"
  60
  61                         /* record DSCR and TEXASR */
  62                         "mfspr   3, %[sprn_dscr];"
  63                         "std     3, %[dscr2];"
  64                         "mfspr   3, %[sprn_texasr];"
  65                         "std     3, %[texasr];"
  66
  67                         "tresume.;"
  68                         "tend.;"
  69                         "li      %[rv], 0;"
  70                         "1: ;"
  71                         : [rv]"=r"(rv), [dscr2]"=m"(dscr2), [texasr]"=m"(texasr)
  72                         : [dscr1]"m"(dscr1)
  73                         , [sprn_dscr]"i"(SPRN_DSCR), [sprn_texasr]"i"(SPRN_TEXASR)
  74                         : "memory", "r3"
  75                 );
  76                 assert(rv); /* make sure the transaction aborted */
  77                 if ((texasr >> 56) != TM_CAUSE_RESCHED) {
  78                         putchar('.');
  79                         fflush(stdout);
  80                         continue;
  81                 }
  82                 if (dscr2 != dscr1) {
  83                         printf(" FAIL\n");
  84                         return 1;
  85                 } else {
  86                         printf(" OK\n");
  87                         return 0;
  88                 }
  89         }
  90 }
  91
  92 int main(void)
  93 {
  94         return test_harness(test_body, "tm_resched_dscr");
  95 }