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// SPDX-License-Identifier: GPL-2.0
/* Test context switching to see if the DSCR SPR is correctly preserved
* when within a transaction.
*
* Note: We assume that the DSCR has been left at the default value (0)
* for all CPUs.
*
* Method:
*
* Set a value into the DSCR.
*
* Start a transaction, and suspend it (*).
*
* Hard loop checking to see if the transaction has become doomed.
*
* Now that we *may* have been preempted, record the DSCR and TEXASR SPRS.
*
* If the abort was because of a context switch, check the DSCR value.
* Otherwise, try again.
*
* (*) If the transaction is not suspended we can't see the problem because
* the transaction abort handler will restore the DSCR to it's checkpointed
* value before we regain control.
*/
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <asm/tm.h>
#include "utils.h"
#include "tm.h"
#include "../pmu/lib.h"
#define SPRN_DSCR 0x03
int test_body(void)
{
uint64_t rv, dscr1 = 1, dscr2, texasr;
SKIP_IF(!have_htm());
printf("Check DSCR TM context switch: ");
fflush(stdout);
for (;;) {
asm __volatile__ (
/* set a known value into the DSCR */
"ld 3, %[dscr1];"
"mtspr %[sprn_dscr], 3;"
"li %[rv], 1;"
/* start and suspend a transaction */
"tbegin.;"
"beq 1f;"
"tsuspend.;"
/* hard loop until the transaction becomes doomed */
"2: ;"
"tcheck 0;"
"bc 4, 0, 2b;"
/* record DSCR and TEXASR */
"mfspr 3, %[sprn_dscr];"
"std 3, %[dscr2];"
"mfspr 3, %[sprn_texasr];"
"std 3, %[texasr];"
"tresume.;"
"tend.;"
"li %[rv], 0;"
"1: ;"
: [rv]"=r"(rv), [dscr2]"=m"(dscr2), [texasr]"=m"(texasr)
: [dscr1]"m"(dscr1)
, [sprn_dscr]"i"(SPRN_DSCR), [sprn_texasr]"i"(SPRN_TEXASR)
: "memory", "r3"
);
assert(rv); /* make sure the transaction aborted */
if ((texasr >> 56) != TM_CAUSE_RESCHED) {
continue;
}
if (dscr2 != dscr1) {
printf(" FAIL\n");
return 1;
} else {
printf(" OK\n");
return 0;
}
}
}
static int tm_resched_dscr(void)
{
return eat_cpu(test_body);
}
int main(int argc, const char *argv[])
{
return test_harness(tm_resched_dscr, "tm_resched_dscr");
}
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