selftests/powerpc: Test preservation of FPU and VMX regs across preemption
authorCyril Bur <cyrilbur@gmail.com>
Mon, 29 Feb 2016 06:53:44 +0000 (17:53 +1100)
committerMichael Ellerman <mpe@ellerman.id.au>
Wed, 2 Mar 2016 12:34:47 +0000 (23:34 +1100)
Loop in assembly checking the registers with many threads.

Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
tools/testing/selftests/powerpc/math/.gitignore
tools/testing/selftests/powerpc/math/Makefile
tools/testing/selftests/powerpc/math/fpu_asm.S
tools/testing/selftests/powerpc/math/fpu_preempt.c [new file with mode: 0644]
tools/testing/selftests/powerpc/math/vmx_asm.S
tools/testing/selftests/powerpc/math/vmx_preempt.c [new file with mode: 0644]

index 418bef1..b6f4158 100644 (file)
@@ -1,4 +1,4 @@
-TEST_PROGS := fpu_syscall vmx_syscall
+TEST_PROGS := fpu_syscall fpu_preempt vmx_syscall vmx_preempt
 
 all: $(TEST_PROGS)
 
@@ -6,7 +6,10 @@ $(TEST_PROGS): ../harness.c
 $(TEST_PROGS): CFLAGS += -O2 -g -pthread -m64 -maltivec
 
 fpu_syscall: fpu_asm.S
+fpu_preempt: fpu_asm.S
+
 vmx_syscall: vmx_asm.S
+vmx_preempt: vmx_asm.S
 
 include ../../lib.mk
 
index 7617da3..f3711d8 100644 (file)
@@ -159,3 +159,40 @@ FUNC_START(test_fpu)
        POP_BASIC_STACK(256)
        blr
 FUNC_END(test_fpu)
+
+# int preempt_fpu(double *darray, int *threads_running, int *running)
+# On starting will (atomically) decrement not_ready as a signal that the FPU
+# has been loaded with darray. Will proceed to check the validity of the FPU
+# registers while running is not zero.
+FUNC_START(preempt_fpu)
+       PUSH_BASIC_STACK(256)
+       std r3,STACK_FRAME_PARAM(0)(sp) # double *darray
+       std r4,STACK_FRAME_PARAM(1)(sp) # int *threads_starting
+       std r5,STACK_FRAME_PARAM(2)(sp) # int *running
+       PUSH_FPU(STACK_FRAME_LOCAL(3,0))
+
+       bl load_fpu
+       nop
+
+       sync
+       # Atomic DEC
+       ld r3,STACK_FRAME_PARAM(1)(sp)
+1:     lwarx r4,0,r3
+       addi r4,r4,-1
+       stwcx. r4,0,r3
+       bne- 1b
+
+2:     ld r3,STACK_FRAME_PARAM(0)(sp)
+       bl check_fpu
+       nop
+       cmpdi r3,0
+       bne 3f
+       ld r4,STACK_FRAME_PARAM(2)(sp)
+       ld r5,0(r4)
+       cmpwi r5,0
+       bne 2b
+
+3:     POP_FPU(STACK_FRAME_LOCAL(3,0))
+       POP_BASIC_STACK(256)
+       blr
+FUNC_END(preempt_fpu)
diff --git a/tools/testing/selftests/powerpc/math/fpu_preempt.c b/tools/testing/selftests/powerpc/math/fpu_preempt.c
new file mode 100644 (file)
index 0000000..0f85b79
--- /dev/null
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2015, Cyril Bur, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * This test attempts to see if the FPU registers change across preemption.
+ * Two things should be noted here a) The check_fpu function in asm only checks
+ * the non volatile registers as it is reused from the syscall test b) There is
+ * no way to be sure preemption happened so this test just uses many threads
+ * and a long wait. As such, a successful test doesn't mean much but a failure
+ * is bad.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+#include "utils.h"
+
+/* Time to wait for workers to get preempted (seconds) */
+#define PREEMPT_TIME 20
+/*
+ * Factor by which to multiply number of online CPUs for total number of
+ * worker threads
+ */
+#define THREAD_FACTOR 8
+
+
+__thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
+                    1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
+                    2.1};
+
+int threads_starting;
+int running;
+
+extern void preempt_fpu(double *darray, int *threads_starting, int *running);
+
+void *preempt_fpu_c(void *p)
+{
+       int i;
+       srand(pthread_self());
+       for (i = 0; i < 21; i++)
+               darray[i] = rand();
+
+       /* Test failed if it ever returns */
+       preempt_fpu(darray, &threads_starting, &running);
+
+       return p;
+}
+
+int test_preempt_fpu(void)
+{
+       int i, rc, threads;
+       pthread_t *tids;
+
+       threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
+       tids = malloc((threads) * sizeof(pthread_t));
+       FAIL_IF(!tids);
+
+       running = true;
+       threads_starting = threads;
+       for (i = 0; i < threads; i++) {
+               rc = pthread_create(&tids[i], NULL, preempt_fpu_c, NULL);
+               FAIL_IF(rc);
+       }
+
+       setbuf(stdout, NULL);
+       /* Not really necessary but nice to wait for every thread to start */
+       printf("\tWaiting for all workers to start...");
+       while(threads_starting)
+               asm volatile("": : :"memory");
+       printf("done\n");
+
+       printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
+       sleep(PREEMPT_TIME);
+       printf("done\n");
+
+       printf("\tStopping workers...");
+       /*
+        * Working are checking this value every loop. In preempt_fpu 'cmpwi r5,0; bne 2b'.
+        * r5 will have loaded the value of running.
+        */
+       running = 0;
+       for (i = 0; i < threads; i++) {
+               void *rc_p;
+               pthread_join(tids[i], &rc_p);
+
+               /*
+                * Harness will say the fail was here, look at why preempt_fpu
+                * returned
+                */
+               if ((long) rc_p)
+                       printf("oops\n");
+               FAIL_IF((long) rc_p);
+       }
+       printf("done\n");
+
+       free(tids);
+       return 0;
+}
+
+int main(int argc, char *argv[])
+{
+       return test_harness(test_preempt_fpu, "fpu_preempt");
+}
index 4ce6421..1b8c248 100644 (file)
@@ -9,6 +9,7 @@
 
 #include "../basic_asm.h"
 
+# POS MUST BE 16 ALIGNED!
 #define PUSH_VMX(pos,reg) \
        li      reg,pos; \
        stvx    v20,reg,sp; \
@@ -35,6 +36,7 @@
        addi    reg,reg,16; \
        stvx    v31,reg,sp;
 
+# POS MUST BE 16 ALIGNED!
 #define POP_VMX(pos,reg) \
        li      reg,pos; \
        lvx     v20,reg,sp; \
@@ -93,7 +95,7 @@ FUNC_END(load_vmx)
 
 # Should be safe from C, only touches r4, r5 and v0,v1,v2
 FUNC_START(check_vmx)
-       PUSH_BASIC_STACK(16)
+       PUSH_BASIC_STACK(32)
        mr r4,r3
        li      r3,1 # assume a bad result
        li      r5,0
@@ -162,7 +164,7 @@ FUNC_START(check_vmx)
        cmpdi   r0,0xffffffffffffffff
        bne     1f
        li      r3,0
-1:     POP_BASIC_STACK(16)
+1:     POP_BASIC_STACK(32)
        blr
 FUNC_END(check_vmx)
 
@@ -193,3 +195,41 @@ FUNC_START(test_vmx)
        POP_BASIC_STACK(512)
        blr
 FUNC_END(test_vmx)
+
+# int preempt_vmx(vector int *varray, int *threads_starting, int *running)
+# On starting will (atomically) decrement threads_starting as a signal that
+# the VMX have been loaded with varray. Will proceed to check the validity of
+# the VMX registers while running is not zero.
+FUNC_START(preempt_vmx)
+       PUSH_BASIC_STACK(512)
+       std r3,STACK_FRAME_PARAM(0)(sp) # vector int *varray
+       std r4,STACK_FRAME_PARAM(1)(sp) # int *threads_starting
+       std r5,STACK_FRAME_PARAM(2)(sp) # int *running
+       # VMX need to write to 16 byte aligned addresses, skip STACK_FRAME_LOCAL(3,0)
+       PUSH_VMX(STACK_FRAME_LOCAL(4,0),r4)
+
+       bl load_vmx
+       nop
+
+       sync
+       # Atomic DEC
+       ld r3,STACK_FRAME_PARAM(1)(sp)
+1:     lwarx r4,0,r3
+       addi r4,r4,-1
+       stwcx. r4,0,r3
+       bne- 1b
+
+2:     ld r3,STACK_FRAME_PARAM(0)(sp)
+       bl check_vmx
+       nop
+       cmpdi r3,0
+       bne 3f
+       ld r4,STACK_FRAME_PARAM(2)(sp)
+       ld r5,0(r4)
+       cmpwi r5,0
+       bne 2b
+
+3:     POP_VMX(STACK_FRAME_LOCAL(4,0),r4)
+       POP_BASIC_STACK(512)
+       blr
+FUNC_END(preempt_vmx)
diff --git a/tools/testing/selftests/powerpc/math/vmx_preempt.c b/tools/testing/selftests/powerpc/math/vmx_preempt.c
new file mode 100644 (file)
index 0000000..9ef376c
--- /dev/null
@@ -0,0 +1,112 @@
+/*
+ * Copyright 2015, Cyril Bur, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * This test attempts to see if the VMX registers change across preemption.
+ * Two things should be noted here a) The check_vmx function in asm only checks
+ * the non volatile registers as it is reused from the syscall test b) There is
+ * no way to be sure preemption happened so this test just uses many threads
+ * and a long wait. As such, a successful test doesn't mean much but a failure
+ * is bad.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+#include "utils.h"
+
+/* Time to wait for workers to get preempted (seconds) */
+#define PREEMPT_TIME 20
+/*
+ * Factor by which to multiply number of online CPUs for total number of
+ * worker threads
+ */
+#define THREAD_FACTOR 8
+
+__thread vector int varray[] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10,11,12},
+       {13,14,15,16},{17,18,19,20},{21,22,23,24},
+       {25,26,27,28},{29,30,31,32},{33,34,35,36},
+       {37,38,39,40},{41,42,43,44},{45,46,47,48}};
+
+int threads_starting;
+int running;
+
+extern void preempt_vmx(vector int *varray, int *threads_starting, int *running);
+
+void *preempt_vmx_c(void *p)
+{
+       int i, j;
+       srand(pthread_self());
+       for (i = 0; i < 12; i++)
+               for (j = 0; j < 4; j++)
+                       varray[i][j] = rand();
+
+       /* Test fails if it ever returns */
+       preempt_vmx(varray, &threads_starting, &running);
+       return p;
+}
+
+int test_preempt_vmx(void)
+{
+       int i, rc, threads;
+       pthread_t *tids;
+
+       threads = sysconf(_SC_NPROCESSORS_ONLN) * THREAD_FACTOR;
+       tids = malloc(threads * sizeof(pthread_t));
+       FAIL_IF(!tids);
+
+       running = true;
+       threads_starting = threads;
+       for (i = 0; i < threads; i++) {
+               rc = pthread_create(&tids[i], NULL, preempt_vmx_c, NULL);
+               FAIL_IF(rc);
+       }
+
+       setbuf(stdout, NULL);
+       /* Not really nessesary but nice to wait for every thread to start */
+       printf("\tWaiting for all workers to start...");
+       while(threads_starting)
+               asm volatile("": : :"memory");
+       printf("done\n");
+
+       printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
+       sleep(PREEMPT_TIME);
+       printf("done\n");
+
+       printf("\tStopping workers...");
+       /*
+        * Working are checking this value every loop. In preempt_vmx 'cmpwi r5,0; bne 2b'.
+        * r5 will have loaded the value of running.
+        */
+       running = 0;
+       for (i = 0; i < threads; i++) {
+               void *rc_p;
+               pthread_join(tids[i], &rc_p);
+
+               /*
+                * Harness will say the fail was here, look at why preempt_vmx
+                * returned
+                */
+               if ((long) rc_p)
+                       printf("oops\n");
+               FAIL_IF((long) rc_p);
+       }
+       printf("done\n");
+
+       return 0;
+}
+
+int main(int argc, char *argv[])
+{
+       return test_harness(test_preempt_vmx, "vmx_preempt");
+}