There's a selftest that checks FPRs aren't corrupted by preemption, or
just process scheduling. However it only checks the non-volatile FPRs,
meaning corruption of the volatile FPRs could go undetected.
The check_fpu function it calls is used by several other tests, so for
now add a new routine to check all the FPRs. Increase the size of the
array of FPRs to 32, and initialise them all with random values.
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
.../testing/selftests/powerpc/math/fpu_asm.S | 41 +++++++++++++++++--
.../selftests/powerpc/math/fpu_preempt.c | 15 +++----
2 files changed, 43 insertions(+), 13 deletions(-)
diff --git a/tools/testing/selftests/powerpc/math/fpu_asm.S
b/tools/testing/selftests/powerpc/math/fpu_asm.S
index 9dc0c158f871..051392ad3ce7 100644
--- a/tools/testing/selftests/powerpc/math/fpu_asm.S
+++ b/tools/testing/selftests/powerpc/math/fpu_asm.S
@@ -66,6 +66,40 @@ FUNC_START(check_fpu)
li r3,0 # Success!!!
1: blr
+
+// int check_all_fprs(double darray[32])
+FUNC_START(check_all_fprs)
+ PUSH_BASIC_STACK(8)
+ mr r4, r3 // r4 = darray
+ li r3, 1 // prepare for failure
+
+ stfd f31, STACK_FRAME_LOCAL(0, 0)(sp) // backup f31
+
+ // Check regs f0-f30, using f31 as scratch
+ .set i, 0
+ .rept 31
+ lfd f31, (8 * i)(r4) // load expected value
+ fcmpu cr0, i, f31 // compare
+ bne cr0, 1f // bail if mismatch
+ .set i, i + 1
+ .endr
+
+ lfd f31, STACK_FRAME_LOCAL(0, 0)(sp) // reload f31
+ stfd f30, STACK_FRAME_LOCAL(0, 0)(sp) // backup f30
+
+ lfd f30, (8 * 31)(r4) // load expected value of f31
+ fcmpu cr0, f30, f31 // compare
+ bne cr0, 1f // bail if mismatch
+
+ lfd f30, STACK_FRAME_LOCAL(0, 0)(sp) // reload f30
+
+ // Success
+ li r3, 0
+
+1: POP_BASIC_STACK(8)
+ blr
+FUNC_END(check_all_fprs)
+
FUNC_START(test_fpu)
# r3 holds pointer to where to put the result of fork
# r4 holds pointer to the pid
@@ -104,8 +138,8 @@ FUNC_START(preempt_fpu)
std r4,STACK_FRAME_PARAM(1)(sp) # int *threads_starting
std r5,STACK_FRAME_PARAM(2)(sp) # int *running
- bl load_fpu
- nop
+ // Load FPRs with expected values
+ OP_REGS lfd, 8, 0, 31, r3
sync
# Atomic DEC
@@ -116,8 +150,7 @@ FUNC_START(preempt_fpu)
bne- 1b
2: ld r3,STACK_FRAME_PARAM(0)(sp)
- bl check_fpu
- nop
+ bl check_all_fprs
cmpdi r3,0
bne 3f
ld r4,STACK_FRAME_PARAM(2)(sp)
diff --git a/tools/testing/selftests/powerpc/math/fpu_preempt.c
b/tools/testing/selftests/powerpc/math/fpu_preempt.c
index 3e5b5663d244..24b5abacccdc 100644
--- a/tools/testing/selftests/powerpc/math/fpu_preempt.c
+++ b/tools/testing/selftests/powerpc/math/fpu_preempt.c
@@ -1,13 +1,12 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2015, Cyril Bur, IBM Corp.
+ * Copyright 2023, Michael Ellerman, IBM Corp.
*
* 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.
+ * 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>
@@ -30,9 +29,7 @@
#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};
+__thread double darray[32];
int threads_starting;
int running;
@@ -45,7 +42,7 @@ void *preempt_fpu_c(void *p)
int i;
srand(pthread_self());
- for (i = 0; i < 21; i++)
+ for (i = 0; i < ARRAY_SIZE(darray); i++)
darray[i] = rand();
rc = preempt_fpu(darray, &threads_starting, &running);
--
2.41.0
