[PATCH] selftests/powerpc: Check FP/VEC on exception in TM
Gustavo Romero
gromero at linux.vnet.ibm.com
Thu Nov 2 06:23:41 AEDT 2017
Add a self test to check if FP/VEC/VSX registers are sane (restored
correctly) after a FP/VEC/VSX unavailable exception is caught during a
transaction.
This test checks all possibilities in a thread regarding the combination
of MSR.[FP|VEC] states in a thread and for each scenario raises a
FP/VEC/VSX unavailable exception in transactional state, verifying if
vs0 and vs32 registers, which are representatives of FP/VEC/VSX reg
sets, are not corrupted.
Signed-off-by: Gustavo Romero <gromero at linux.vnet.ibm.com>
Signed-off-by: Breno Leitao <leitao at debian.org>
Signed-off-by: Cyril Bur <cyrilbur at gmail.com>
---
tools/testing/selftests/powerpc/tm/Makefile | 3 +-
.../testing/selftests/powerpc/tm/tm-unavailable.c | 368 +++++++++++++++++++++
tools/testing/selftests/powerpc/tm/tm.h | 5 +
3 files changed, 375 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/powerpc/tm/tm-unavailable.c
diff --git a/tools/testing/selftests/powerpc/tm/Makefile b/tools/testing/selftests/powerpc/tm/Makefile
index 7bfcd45..24855c0 100644
--- a/tools/testing/selftests/powerpc/tm/Makefile
+++ b/tools/testing/selftests/powerpc/tm/Makefile
@@ -2,7 +2,7 @@ SIGNAL_CONTEXT_CHK_TESTS := tm-signal-context-chk-gpr tm-signal-context-chk-fpu
tm-signal-context-chk-vmx tm-signal-context-chk-vsx
TEST_GEN_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv tm-signal-stack \
- tm-vmxcopy tm-fork tm-tar tm-tmspr tm-vmx-unavail \
+ tm-vmxcopy tm-fork tm-tar tm-tmspr tm-vmx-unavail tm-unavailable \
$(SIGNAL_CONTEXT_CHK_TESTS)
include ../../lib.mk
@@ -16,6 +16,7 @@ $(OUTPUT)/tm-syscall: CFLAGS += -I../../../../../usr/include
$(OUTPUT)/tm-tmspr: CFLAGS += -pthread
$(OUTPUT)/tm-vmx-unavail: CFLAGS += -pthread -m64
$(OUTPUT)/tm-resched-dscr: ../pmu/lib.o
+$(OUTPUT)/tm-unavailable: CFLAGS += -O0 -pthread -m64 -Wno-error=uninitialized -mvsx
SIGNAL_CONTEXT_CHK_TESTS := $(patsubst %,$(OUTPUT)/%,$(SIGNAL_CONTEXT_CHK_TESTS))
$(SIGNAL_CONTEXT_CHK_TESTS): tm-signal.S
diff --git a/tools/testing/selftests/powerpc/tm/tm-unavailable.c b/tools/testing/selftests/powerpc/tm/tm-unavailable.c
new file mode 100644
index 0000000..69a4e8c
--- /dev/null
+++ b/tools/testing/selftests/powerpc/tm/tm-unavailable.c
@@ -0,0 +1,368 @@
+/*
+ * 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 <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
+
+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 *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_)) {
+ 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.
+ */
+ if (is_failure(cr_) && !failure_is_unavailable()) {
+ 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 *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 {
+ /* Bind 'ping' to CPU 0, as specified in 'attr'. */
+ pthread_create(&t0, attr, ping, (void *) &flags);
+ pthread_setname_np(t0, "ping");
+ pthread_join(t0, &ret_value);
+ retries--;
+ } while (ret_value != NULL && retries);
+
+ if (!retries) {
+ flags.result = 1;
+ if (DEBUG)
+ printf("All transactions failed unexpectedly\n");
+
+ }
+}
+
+int main(int argc, char **argv)
+{
+ int exception; /* FP = 0, VEC = 1, VSX = 2 */
+ pthread_t t1;
+ pthread_attr_t attr;
+ cpu_set_t cpuset;
+
+ /* 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. */
+ pthread_attr_init(&attr);
+
+ /* Set CPU 0 mask into the pthread attribute. */
+ pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
+
+ pthread_create(&t1, &attr /* Bind 'pong' to CPU 0 */, pong, NULL);
+ pthread_setname_np(t1, "pong"); /* Name it for systemtap convenience */
+
+ 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);
+ }
+}
diff --git a/tools/testing/selftests/powerpc/tm/tm.h b/tools/testing/selftests/powerpc/tm/tm.h
index 0ffff04..df42042 100644
--- a/tools/testing/selftests/powerpc/tm/tm.h
+++ b/tools/testing/selftests/powerpc/tm/tm.h
@@ -47,6 +47,11 @@ static inline bool failure_is_syscall(void)
return (failure_code() & TM_CAUSE_SYSCALL) == TM_CAUSE_SYSCALL;
}
+static inline bool failure_is_unavailable(void)
+{
+ return (failure_code() & TM_CAUSE_FAC_UNAV) == TM_CAUSE_FAC_UNAV;
+}
+
static inline bool failure_is_nesting(void)
{
return (__builtin_get_texasru() & 0x400000);
--
2.7.4
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