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selftests/powerpc: Check all FPRs in fpu_preempt
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 <mpe@ellerman.id.au>
Link: https://msgid.link/20231128132748.1990179-2-mpe@ellerman.id.au
+43
-13
+37
-4
tools/testing/selftests/powerpc/math/fpu_asm.S
+37
-4
tools/testing/selftests/powerpc/math/fpu_asm.S
···
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li r3,0 # Success!!!
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1: blr
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+
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// int check_all_fprs(double darray[32])
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FUNC_START(check_all_fprs)
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PUSH_BASIC_STACK(8)
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mr r4, r3 // r4 = darray
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li r3, 1 // prepare for failure
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+
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stfd f31, STACK_FRAME_LOCAL(0, 0)(sp) // backup f31
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+
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// Check regs f0-f30, using f31 as scratch
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.set i, 0
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.rept 31
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lfd f31, (8 * i)(r4) // load expected value
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fcmpu cr0, i, f31 // compare
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bne cr0, 1f // bail if mismatch
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.set i, i + 1
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.endr
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lfd f31, STACK_FRAME_LOCAL(0, 0)(sp) // reload f31
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stfd f30, STACK_FRAME_LOCAL(0, 0)(sp) // backup f30
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lfd f30, (8 * 31)(r4) // load expected value of f31
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fcmpu cr0, f30, f31 // compare
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bne cr0, 1f // bail if mismatch
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lfd f30, STACK_FRAME_LOCAL(0, 0)(sp) // reload f30
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// Success
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li r3, 0
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+
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1: POP_BASIC_STACK(8)
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blr
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FUNC_END(check_all_fprs)
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+
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FUNC_START(test_fpu)
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# r3 holds pointer to where to put the result of fork
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# r4 holds pointer to the pid
···
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std r4,STACK_FRAME_PARAM(1)(sp) # int *threads_starting
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std r5,STACK_FRAME_PARAM(2)(sp) # int *running
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-
bl load_fpu
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-
nop
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// Load FPRs with expected values
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OP_REGS lfd, 8, 0, 31, r3
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sync
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# Atomic DEC
···
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bne- 1b
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2: ld r3,STACK_FRAME_PARAM(0)(sp)
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bl check_fpu
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-
nop
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+
bl check_all_fprs
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cmpdi r3,0
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bne 3f
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ld r4,STACK_FRAME_PARAM(2)(sp)
+6
-9
tools/testing/selftests/powerpc/math/fpu_preempt.c
+6
-9
tools/testing/selftests/powerpc/math/fpu_preempt.c
···
1
1
// SPDX-License-Identifier: GPL-2.0-or-later
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2
/*
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* Copyright 2015, Cyril Bur, IBM Corp.
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* Copyright 2023, Michael Ellerman, IBM Corp.
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*
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* This test attempts to see if the FPU registers change across preemption.
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-
* Two things should be noted here a) The check_fpu function in asm only checks
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* the non volatile registers as it is reused from the syscall test b) There is
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* no way to be sure preemption happened so this test just uses many threads
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* and a long wait. As such, a successful test doesn't mean much but a failure
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* is bad.
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* There is no way to be sure preemption happened so this test just uses many
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* threads and a long wait. As such, a successful test doesn't mean much but
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* a failure is bad.
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*/
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#include <stdio.h>
···
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#define THREAD_FACTOR 8
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-
__thread double darray[] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
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1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
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2.1};
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+
__thread double darray[32];
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int threads_starting;
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int running;
···
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int i;
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srand(pthread_self());
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-
for (i = 0; i < 21; i++)
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+
for (i = 0; i < ARRAY_SIZE(darray); i++)
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darray[i] = rand();
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rc = preempt_fpu(darray, &threads_starting, &running);