Linux 4.19.133

[linux/fpc-iii.git] / tools / testing / selftests / powerpc / tm / tm-unavailable.c

/*
 * Copyright 2017, Gustavo Romero, Breno Leitao, Cyril Bur, IBM Corp.
 * Licensed under GPLv2.
 *
 * Force FP, VEC and VSX unavailable exception during transaction in all
 * possible scenarios regarding the MSR.FP and MSR.VEC state, e.g. when FP
 * is enable and VEC is disable, when FP is disable and VEC is enable, and
 * so on. Then we check if the restored state is correctly set for the
 * FP and VEC registers to the previous state we set just before we entered
 * in TM, i.e. we check if it corrupts somehow the recheckpointed FP and
 * VEC/Altivec registers on abortion due to an unavailable exception in TM.
 * N.B. In this test we do not test all the FP/Altivec/VSX registers for
 * corruption, but only for registers vs0 and vs32, which are respectively
 * representatives of FP and VEC/Altivec reg sets.
 */

#define _GNU_SOURCE
#include <error.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <inttypes.h>
#include <stdbool.h>
#include <pthread.h>
#include <sched.h>

#include "tm.h"

#define DEBUG 0

/* Unavailable exceptions to test in HTM */
#define FP_UNA_EXCEPTION        0
#define VEC_UNA_EXCEPTION       1
#define VSX_UNA_EXCEPTION       2

#define NUM_EXCEPTIONS          3
#define err_at_line(status, errnum, format, ...) \
        error_at_line(status, errnum,  __FILE__, __LINE__, format ##__VA_ARGS__)

#define pr_warn(code, format, ...) err_at_line(0, code, format, ##__VA_ARGS__)
#define pr_err(code, format, ...) err_at_line(1, code, format, ##__VA_ARGS__)

struct Flags {
        int touch_fp;
        int touch_vec;
        int result;
        int exception;
} flags;

bool expecting_failure(void)
{
        if (flags.touch_fp && flags.exception == FP_UNA_EXCEPTION)
                return false;

        if (flags.touch_vec && flags.exception == VEC_UNA_EXCEPTION)
                return false;

        /*
         * If both FP and VEC are touched it does not mean that touching VSX
         * won't raise an exception. However since FP and VEC state are already
         * correctly loaded, the transaction is not aborted (i.e.
         * treclaimed/trecheckpointed) and MSR.VSX is just set as 1, so a TM
         * failure is not expected also in this case.
         */
        if ((flags.touch_fp && flags.touch_vec) &&
             flags.exception == VSX_UNA_EXCEPTION)
                return false;

        return true;
}

/* Check if failure occurred whilst in transaction. */
bool is_failure(uint64_t condition_reg)
{
        /*
         * When failure handling occurs, CR0 is set to 0b1010 (0xa). Otherwise
         * transaction completes without failure and hence reaches out 'tend.'
         * that sets CR0 to 0b0100 (0x4).
         */
        return ((condition_reg >> 28) & 0xa) == 0xa;
}

void *tm_una_ping(void *input)
{

        /*
         * Expected values for vs0 and vs32 after a TM failure. They must never
         * change, otherwise they got corrupted.
         */
        uint64_t high_vs0 = 0x5555555555555555;
        uint64_t low_vs0 = 0xffffffffffffffff;
        uint64_t high_vs32 = 0x5555555555555555;
        uint64_t low_vs32 = 0xffffffffffffffff;

        /* Counter for busy wait */
        uint64_t counter = 0x1ff000000;

        /*
         * Variable to keep a copy of CR register content taken just after we
         * leave the transactional state.
         */
        uint64_t cr_ = 0;

        /*
         * Wait a bit so thread can get its name "ping". This is not important
         * to reproduce the issue but it's nice to have for systemtap debugging.
         */
        if (DEBUG)
                sleep(1);

        printf("If MSR.FP=%d MSR.VEC=%d: ", flags.touch_fp, flags.touch_vec);

        if (flags.exception != FP_UNA_EXCEPTION &&
            flags.exception != VEC_UNA_EXCEPTION &&
            flags.exception != VSX_UNA_EXCEPTION) {
                printf("No valid exception specified to test.\n");
                return NULL;
        }

        asm (
                /* Prepare to merge low and high. */
                "       mtvsrd          33, %[high_vs0]         ;"
                "       mtvsrd          34, %[low_vs0]          ;"

                /*
                 * Adjust VS0 expected value after an TM failure,
                 * i.e. vs0 = 0x5555555555555555555FFFFFFFFFFFFFFFF
                 */
                "       xxmrghd         0, 33, 34               ;"

                /*
                 * Adjust VS32 expected value after an TM failure,
                 * i.e. vs32 = 0x5555555555555555555FFFFFFFFFFFFFFFF
                 */
                "       xxmrghd         32, 33, 34              ;"

                /*
                 * Wait an amount of context switches so load_fp and load_vec
                 * overflow and MSR.FP, MSR.VEC, and MSR.VSX become zero (off).
                 */
                "       mtctr           %[counter]              ;"

                /* Decrement CTR branch if CTR non zero. */
                "1:     bdnz 1b                                 ;"

                /*
                 * Check if we want to touch FP prior to the test in order
                 * to set MSR.FP = 1 before provoking an unavailable
                 * exception in TM.
                 */
                "       cmpldi          %[touch_fp], 0          ;"
                "       beq             no_fp                   ;"
                "       fadd            10, 10, 10              ;"
                "no_fp:                                         ;"

                /*
                 * Check if we want to touch VEC prior to the test in order
                 * to set MSR.VEC = 1 before provoking an unavailable
                 * exception in TM.
                 */
                "       cmpldi          %[touch_vec], 0         ;"
                "       beq             no_vec                  ;"
                "       vaddcuw         10, 10, 10              ;"
                "no_vec:                                        ;"

                /*
                 * Perhaps it would be a better idea to do the
                 * compares outside transactional context and simply
                 * duplicate code.
                 */
                "       tbegin.                                 ;"
                "       beq             trans_fail              ;"

                /* Do we do FP Unavailable? */
                "       cmpldi          %[exception], %[ex_fp]  ;"
                "       bne             1f                      ;"
                "       fadd            10, 10, 10              ;"
                "       b               done                    ;"

                /* Do we do VEC Unavailable? */
                "1:     cmpldi          %[exception], %[ex_vec] ;"
                "       bne             2f                      ;"
                "       vaddcuw         10, 10, 10              ;"
                "       b               done                    ;"

                /*
                 * Not FP or VEC, therefore VSX. Ensure this
                 * instruction always generates a VSX Unavailable.
                 * ISA 3.0 is tricky here.
                 * (xxmrghd will on ISA 2.07 and ISA 3.0)
                 */
                "2:     xxmrghd         10, 10, 10              ;"

                "done:  tend. ;"

                "trans_fail: ;"

                /* Give values back to C. */
                "       mfvsrd          %[high_vs0], 0          ;"
                "       xxsldwi         3, 0, 0, 2              ;"
                "       mfvsrd          %[low_vs0], 3           ;"
                "       mfvsrd          %[high_vs32], 32        ;"
                "       xxsldwi         3, 32, 32, 2            ;"
                "       mfvsrd          %[low_vs32], 3          ;"

                /* Give CR back to C so that it can check what happened. */
                "       mfcr            %[cr_]          ;"

                : [high_vs0]  "+r" (high_vs0),
                  [low_vs0]   "+r" (low_vs0),
                  [high_vs32] "=r" (high_vs32),
                  [low_vs32]  "=r" (low_vs32),
                  [cr_]       "+r" (cr_)
                : [touch_fp]  "r"  (flags.touch_fp),
                  [touch_vec] "r"  (flags.touch_vec),
                  [exception] "r"  (flags.exception),
                  [ex_fp]     "i"  (FP_UNA_EXCEPTION),
                  [ex_vec]    "i"  (VEC_UNA_EXCEPTION),
                  [ex_vsx]    "i"  (VSX_UNA_EXCEPTION),
                  [counter]   "r"  (counter)

                : "cr0", "ctr", "v10", "vs0", "vs10", "vs3", "vs32", "vs33",
                  "vs34", "fr10"

                );

        /*
         * Check if we were expecting a failure and it did not occur by checking
         * CR0 state just after we leave the transaction. Either way we check if
         * vs0 or vs32 got corrupted.
         */
        if (expecting_failure() && !is_failure(cr_)) {
                printf("\n\tExpecting the transaction to fail, %s",
                        "but it didn't\n\t");
                flags.result++;
        }

        /* Check if we were not expecting a failure and a it occurred. */
        if (!expecting_failure() && is_failure(cr_) &&
            !failure_is_reschedule()) {
                printf("\n\tUnexpected transaction failure 0x%02lx\n\t",
                        failure_code());
                return (void *) -1;
        }

        /*
         * Check if TM failed due to the cause we were expecting. 0xda is a
         * TM_CAUSE_FAC_UNAV cause, otherwise it's an unexpected cause, unless
         * it was caused by a reschedule.
         */
        if (is_failure(cr_) && !failure_is_unavailable() &&
            !failure_is_reschedule()) {
                printf("\n\tUnexpected failure cause 0x%02lx\n\t",
                        failure_code());
                return (void *) -1;
        }

        /* 0x4 is a success and 0xa is a fail. See comment in is_failure(). */
        if (DEBUG)
                printf("CR0: 0x%1lx ", cr_ >> 28);

        /* Check FP (vs0) for the expected value. */
        if (high_vs0 != 0x5555555555555555 || low_vs0 != 0xFFFFFFFFFFFFFFFF) {
                printf("FP corrupted!");
                        printf("  high = %#16" PRIx64 "  low = %#16" PRIx64 " ",
                                high_vs0, low_vs0);
                flags.result++;
        } else
                printf("FP ok ");

        /* Check VEC (vs32) for the expected value. */
        if (high_vs32 != 0x5555555555555555 || low_vs32 != 0xFFFFFFFFFFFFFFFF) {
                printf("VEC corrupted!");
                        printf("  high = %#16" PRIx64 "  low = %#16" PRIx64,
                                high_vs32, low_vs32);
                flags.result++;
        } else
                printf("VEC ok");

        putchar('\n');

        return NULL;
}

/* Thread to force context switch */
void *tm_una_pong(void *not_used)
{
        /* Wait thread get its name "pong". */
        if (DEBUG)
                sleep(1);

        /* Classed as an interactive-like thread. */
        while (1)
                sched_yield();
}

/* Function that creates a thread and launches the "ping" task. */
void test_fp_vec(int fp, int vec, pthread_attr_t *attr)
{
        int retries = 2;
        void *ret_value;
        pthread_t t0;

        flags.touch_fp = fp;
        flags.touch_vec = vec;

        /*
         * Without luck it's possible that the transaction is aborted not due to
         * the unavailable exception caught in the middle as we expect but also,
         * for instance, due to a context switch or due to a KVM reschedule (if
         * it's running on a VM). Thus we try a few times before giving up,
         * checking if the failure cause is the one we expect.
         */
        do {
                int rc;

                /* Bind to CPU 0, as specified in 'attr'. */
                rc = pthread_create(&t0, attr, tm_una_ping, (void *) &flags);
                if (rc)
                        pr_err(rc, "pthread_create()");
                rc = pthread_setname_np(t0, "tm_una_ping");
                if (rc)
                        pr_warn(rc, "pthread_setname_np");
                rc = pthread_join(t0, &ret_value);
                if (rc)
                        pr_err(rc, "pthread_join");

                retries--;
        } while (ret_value != NULL && retries);

        if (!retries) {
                flags.result = 1;
                if (DEBUG)
                        printf("All transactions failed unexpectedly\n");

        }
}

int tm_unavailable_test(void)
{
        int rc, exception; /* FP = 0, VEC = 1, VSX = 2 */
        pthread_t t1;
        pthread_attr_t attr;
        cpu_set_t cpuset;

        SKIP_IF(!have_htm());

        /* Set only CPU 0 in the mask. Both threads will be bound to CPU 0. */
        CPU_ZERO(&cpuset);
        CPU_SET(0, &cpuset);

        /* Init pthread attribute. */
        rc = pthread_attr_init(&attr);
        if (rc)
                pr_err(rc, "pthread_attr_init()");

        /* Set CPU 0 mask into the pthread attribute. */
        rc = pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
        if (rc)
                pr_err(rc, "pthread_attr_setaffinity_np()");

        rc = pthread_create(&t1, &attr /* Bind to CPU 0 */, tm_una_pong, NULL);
        if (rc)
                pr_err(rc, "pthread_create()");

        /* Name it for systemtap convenience */
        rc = pthread_setname_np(t1, "tm_una_pong");
        if (rc)
                pr_warn(rc, "pthread_create()");

        flags.result = 0;

        for (exception = 0; exception < NUM_EXCEPTIONS; exception++) {
                printf("Checking if FP/VEC registers are sane after");

                if (exception == FP_UNA_EXCEPTION)
                        printf(" a FP unavailable exception...\n");

                else if (exception == VEC_UNA_EXCEPTION)
                        printf(" a VEC unavailable exception...\n");

                else
                        printf(" a VSX unavailable exception...\n");

                flags.exception = exception;

                test_fp_vec(0, 0, &attr);
                test_fp_vec(1, 0, &attr);
                test_fp_vec(0, 1, &attr);
                test_fp_vec(1, 1, &attr);

        }

        if (flags.result > 0) {
                printf("result: failed!\n");
                exit(1);
        } else {
                printf("result: success\n");
                exit(0);
        }
}

int main(int argc, char **argv)
{
        test_harness_set_timeout(220);
        return test_harness(tm_unavailable_test, "tm_unavailable_test");
}