[PATCH 2/8] selftests/powerpc: Test preservation of FPU and VMX regs across preemption
Michael Neuling
mikey at neuling.org
Mon Nov 23 11:34:30 AEDT 2015
On Wed, 2015-11-18 at 14:26 +1100, Cyril Bur wrote:
> Loop in assembly checking the registers with many threads.
>
> Signed-off-by: Cyril Bur <cyrilbur at gmail.com>
> ---
> tools/testing/selftests/powerpc/math/Makefile | 7 +-
> tools/testing/selftests/powerpc/math/fpu_asm.S | 34 ++++++++
> tools/testing/selftests/powerpc/math/fpu_preempt.c | 92 ++++++++++++++++++++++
> tools/testing/selftests/powerpc/math/vmx_asm.S | 44 ++++++++++-
> tools/testing/selftests/powerpc/math/vmx_preempt.c | 92 ++++++++++++++++++++++
> 5 files changed, 263 insertions(+), 6 deletions(-)
> create mode 100644 tools/testing/selftests/powerpc/math/fpu_preempt.c
> create mode 100644 tools/testing/selftests/powerpc/math/vmx_preempt.c
>
> diff --git a/tools/testing/selftests/powerpc/math/Makefile
b/tools/testing/selftests/powerpc/math/Makefile
> index 896d9e2..9fa690f 100644
> --- a/tools/testing/selftests/powerpc/math/Makefile
> +++ b/tools/testing/selftests/powerpc/math/Makefile
> @@ -1,12 +1,15 @@
> -TEST_PROGS := fpu_syscall vmx_syscall
> +TEST_PROGS := fpu_syscall fpu_preempt vmx_syscall vmx_preempt
.gitignore for this new build object
> all: $(TEST_PROGS)
>
> $(TEST_PROGS): ../harness.c
> -$(TEST_PROGS): CFLAGS += -O2 -g
> +$(TEST_PROGS): CFLAGS += -O2 -g -pthread
>
> fpu_syscall: fpu_asm.S
> +fpu_preempt: fpu_asm.S
> +
> vmx_syscall: vmx_asm.S
> +vmx_preempt: vmx_asm.S
>
> include ../../lib.mk
>
> diff --git a/tools/testing/selftests/powerpc/math/fpu_asm.S b/tools/testing/selftests/powerpc/math/fpu_asm.S
> index d5412c1..5ff0adc 100644
> --- a/tools/testing/selftests/powerpc/math/fpu_asm.S
> +++ b/tools/testing/selftests/powerpc/math/fpu_asm.S
> @@ -149,3 +149,37 @@ FUNC_START(test_fpu)
> > > POP_BASIC_STACK(256)
> > > blr
> FUNC_END(test_fpu)
> +
> +#int preempt_fpu(double *darray, volatile int *not_ready, int *sentinal)
> +#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 sentinal is not zero.
> +FUNC_START(preempt_fpu)
> +> > PUSH_BASIC_STACK(256)
> +> > std r3,32(sp) #double *darray
> +> > std r4,40(sp) #volatile int *not_ready
> +> > std r5,48(sp) #int *sentinal
> +> > PUSH_FPU(56)
> +
> +> > bl load_fpu
> +
Memory barrier here.
> +> > #Atomic DEC
> +> > ld r3,40(sp)
> +1:> > lwarx r4,0,r3
> +> > addi r4,r4,-1
> +> > stwcx. r4,0,r3
> +> > bne- 1b
> +
> +2:> > ld r3, 32(sp)
> +> > bl check_fpu
> +> > cmpdi r3,0
> +> > bne 3f
> +> > ld r4, 48(sp)
> +> > ld r5, 0(r4)
> +> > cmpwi r5,0
> +> > bne 2b
> +
> +3:> > POP_FPU(56)
> +> > 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
> index 0000000..e24cf9b
> --- /dev/null
> +++ b/tools/testing/selftests/powerpc/math/fpu_preempt.c
Needs a copyright and a description of the test here.
Same in patch 1.
> @@ -0,0 +1,92 @@
> +#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};
> +
> +volatile int not_ready;
> +int running;
> +
> +extern void preempt_fpu(double *darray, volatile int *not_ready, int *sentinal);
> +
> +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, ¬_ready, &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;
> +> > not_ready = 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 nessesary but nice to wait for every thread to start */
> +> > printf("\tWaiting for all workers to start...");
> +> > while(not_ready);
You need a memory barrier here and a matching one in the asm which is
derementing it. Same in the VSX test.
> +> > printf("done\n");
> +
> +> > printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
> +> > sleep(PREEMPT_TIME);
> +> > printf("done\n");
> +
> +> > printf("\tKilling workers...");
> +> > 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");
> +}
> diff --git a/tools/testing/selftests/powerpc/math/vmx_asm.S b/tools/testing/selftests/powerpc/math/vmx_asm.S
> index e642e67..23db4b3 100644
> --- a/tools/testing/selftests/powerpc/math/vmx_asm.S
> +++ b/tools/testing/selftests/powerpc/math/vmx_asm.S
> @@ -1,5 +1,6 @@
> #include "basic_asm.h"
>
> +#POS MUST BE 16 ALIGNED!
> #define PUSH_VMX(pos,reg) \
> > > li> > reg,pos; \
> > > stvx> > v20,reg,sp; \
> @@ -26,6 +27,7 @@
> > > 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; \
> @@ -84,7 +86,7 @@ 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
> @@ -153,7 +155,7 @@ FUNC_START(check_vmx)
> > > cmpdi> > r0,0xffffffff
> > > bne> > 1f
> > > li> > r3,0
> -1:> > POP_BASIC_STACK(16)
> +1:> > POP_BASIC_STACK(32)
> > > blr
> FUNC_END(check_vmx)
>
> @@ -164,7 +166,7 @@ FUNC_START(test_vmx)
> > > PUSH_BASIC_STACK(512)
> > > std> > r3,40(sp) #Address of varray
> > > std r4,48(sp) #address of pid
> -> > PUSH_VMX(56, r4)
> +> > PUSH_VMX(64, r4)
>
> > > bl load_vmx
>
> @@ -177,7 +179,41 @@ FUNC_START(test_vmx)
> > > ld r3,40(sp)
> > > bl check_vmx
>
> -> > POP_VMX(56,r4)
> +> > POP_VMX(64,r4)
> > > POP_BASIC_STACK(512)
> > > blr
> FUNC_END(test_vmx)
> +
> +#int preempt_vmx(v4si *varray, volatile int *not_ready, int *sentinal)
> +#On starting will (atomically) decrement not_ready as a signal that the FPU
> +#has been loaded with varray. Will proceed to check the validity of the FPU
> +#registers while sentinal is not zero.
> +FUNC_START(preempt_vmx)
> +> > PUSH_BASIC_STACK(512)
> +> > std r3,32(sp) #v4si *varray
> +> > std r4,40(sp) #volatile int *not_ready
> +> > std r5,48(sp) #int *sentinal
> +> > PUSH_VMX(64,r4)
> +
> +> > bl load_vmx
> +
Memory barrier here
> +> > #Atomic DEC
> +> > ld r3,40(sp)
> +1:> > lwarx r4,0,r3
> +> > addi r4,r4,-1
> +> > stwcx. r4,0,r3
> +> > bne- 1b
> +
> +2:> > ld r3,32(sp)
> +> > bl check_vmx
> +> > cmpdi r3,0
> +> > bne 3f
> +> > ld r4,48(sp)
> +> > ld r5,0(r4)
> +> > cmpwi r5,0
> +> > bne 2b
> +
> +3:> > POP_VMX(64,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
> index 0000000..342db15
> --- /dev/null
> +++ b/tools/testing/selftests/powerpc/math/vmx_preempt.c
Needs a copyright and a description of the test here.
> @@ -0,0 +1,92 @@
> +#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
> +
> +typedef int v4si __attribute__ ((vector_size (16)));
> +__thread v4si 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}};
> +
> +volatile int not_ready;
I really hate this name. How about just "ready" and you negate the
code.
> +int running;
Now about not_running ;-P
> +
> +extern void preempt_vmx(v4si *varray, volatile int *not_ready, int *sentinal);
> +
> +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, ¬_ready, &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;
> +> > not_ready = 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(not_ready);
Again, a memory barrier here.
> +> > printf("done\n");
> +
> +> > printf("\tWaiting for %d seconds to let some workers get preempted...", PREEMPT_TIME);
> +> > sleep(PREEMPT_TIME);
> +> > printf("done\n");
> +
> +> > printf("\tKilling workers...");
> +> > 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");
> +}
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