diff mbox series

[v1,1/3] kselftest/arm64: Provide a helper binary and "library" for SVE RDVL

Message ID 20210727180649.12943-2-broonie@kernel.org
State Superseded
Headers show
Series kselftest/arm64: Vector length configuration tests | expand

Commit Message

Mark Brown July 27, 2021, 6:06 p.m. UTC
SVE provides an instruction RDVL which reports the currently configured
vector length. In order to validate that our vector length configuration
interfaces are working correctly without having to build the C code for
our test programs with SVE enabled provide a trivial assembly library
with a C callable function that executes RDVL. Since these interfaces
also control behaviour on exec*() provide a trivial wrapper program which
reports the currently configured vector length on stdout, tests can use
this to verify that behaviour on exec*() is as expected.

In preparation for providing similar helper functionality for SME, the
Scalable Matrix Extension, which allows separately configured vector
lengths to be read back both the assembler function and wrapper binary
have SVE included in their name.

Signed-off-by: Mark Brown <broonie@kernel.org>

---
 tools/testing/selftests/arm64/fp/.gitignore |  1 +
 tools/testing/selftests/arm64/fp/Makefile   |  6 +++++-
 tools/testing/selftests/arm64/fp/rdvl-sve.c | 14 ++++++++++++++
 tools/testing/selftests/arm64/fp/rdvl.S     |  9 +++++++++
 tools/testing/selftests/arm64/fp/rdvl.h     |  8 ++++++++
 5 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/arm64/fp/rdvl-sve.c
 create mode 100644 tools/testing/selftests/arm64/fp/rdvl.S
 create mode 100644 tools/testing/selftests/arm64/fp/rdvl.h

-- 
2.20.1

Comments

Dave Martin July 28, 2021, 9:41 a.m. UTC | #1
On Tue, Jul 27, 2021 at 07:06:47PM +0100, Mark Brown wrote:
> SVE provides an instruction RDVL which reports the currently configured

> vector length. In order to validate that our vector length configuration

> interfaces are working correctly without having to build the C code for

> our test programs with SVE enabled provide a trivial assembly library

> with a C callable function that executes RDVL. Since these interfaces

> also control behaviour on exec*() provide a trivial wrapper program which

> reports the currently configured vector length on stdout, tests can use

> this to verify that behaviour on exec*() is as expected.

> 

> In preparation for providing similar helper functionality for SME, the

> Scalable Matrix Extension, which allows separately configured vector

> lengths to be read back both the assembler function and wrapper binary

> have SVE included in their name.

> 

> Signed-off-by: Mark Brown <broonie@kernel.org>

> ---

>  tools/testing/selftests/arm64/fp/.gitignore |  1 +

>  tools/testing/selftests/arm64/fp/Makefile   |  6 +++++-

>  tools/testing/selftests/arm64/fp/rdvl-sve.c | 14 ++++++++++++++

>  tools/testing/selftests/arm64/fp/rdvl.S     |  9 +++++++++

>  tools/testing/selftests/arm64/fp/rdvl.h     |  8 ++++++++

>  5 files changed, 37 insertions(+), 1 deletion(-)

>  create mode 100644 tools/testing/selftests/arm64/fp/rdvl-sve.c

>  create mode 100644 tools/testing/selftests/arm64/fp/rdvl.S

>  create mode 100644 tools/testing/selftests/arm64/fp/rdvl.h

> 

> diff --git a/tools/testing/selftests/arm64/fp/.gitignore b/tools/testing/selftests/arm64/fp/.gitignore

> index d66f76d2a650..6b53a7b60fee 100644

> --- a/tools/testing/selftests/arm64/fp/.gitignore

> +++ b/tools/testing/selftests/arm64/fp/.gitignore

> @@ -1,4 +1,5 @@

>  fpsimd-test

> +rdvl-sve

>  sve-probe-vls

>  sve-ptrace

>  sve-test

> diff --git a/tools/testing/selftests/arm64/fp/Makefile b/tools/testing/selftests/arm64/fp/Makefile

> index a57009d3a0dc..ed62e7003b96 100644

> --- a/tools/testing/selftests/arm64/fp/Makefile

> +++ b/tools/testing/selftests/arm64/fp/Makefile

> @@ -2,12 +2,16 @@

>  

>  CFLAGS += -I../../../../../usr/include/

>  TEST_GEN_PROGS := sve-ptrace sve-probe-vls

> -TEST_PROGS_EXTENDED := fpsimd-test fpsimd-stress sve-test sve-stress vlset

> +TEST_PROGS_EXTENDED := fpsimd-test fpsimd-stress \

> +	rdvl-sve \

> +	sve-test sve-stress \

> +	vlset

>  

>  all: $(TEST_GEN_PROGS) $(TEST_PROGS_EXTENDED)

>  

>  fpsimd-test: fpsimd-test.o

>  	$(CC) -nostdlib $^ -o $@

> +rdvl-sve: rdvl-sve.o rdvl.o

>  sve-ptrace: sve-ptrace.o sve-ptrace-asm.o

>  sve-probe-vls: sve-probe-vls.o

>  sve-test: sve-test.o

> diff --git a/tools/testing/selftests/arm64/fp/rdvl-sve.c b/tools/testing/selftests/arm64/fp/rdvl-sve.c

> new file mode 100644

> index 000000000000..7f8a13a18f5d

> --- /dev/null

> +++ b/tools/testing/selftests/arm64/fp/rdvl-sve.c

> @@ -0,0 +1,14 @@

> +// SPDX-License-Identifier: GPL-2.0-only

> +

> +#include <stdio.h>

> +

> +#include "rdvl.h"

> +

> +int main(void)

> +{

> +	int vl = rdvl_sve();

> +

> +	printf("%d\n", vl);

> +

> +	return 0;

> +}

> diff --git a/tools/testing/selftests/arm64/fp/rdvl.S b/tools/testing/selftests/arm64/fp/rdvl.S

> new file mode 100644

> index 000000000000..6e76dd720b87

> --- /dev/null

> +++ b/tools/testing/selftests/arm64/fp/rdvl.S

> @@ -0,0 +1,9 @@

> +// SPDX-License-Identifier: GPL-2.0-only

> +// Copyright (C) 2021 ARM Limited.

> +

> +.arch_extension sve

> +

> +.globl rdvl_sve

> +rdvl_sve:

> +	rdvl	x0, #1

> +	ret


This works, but can we use an ACLE intrinsic for this?  I'm pretty GCC
and LLVM have been up to date with that stuff for some time, though
you'd have to check with the compiler folks.

Alternatively:

static int rvdl_sve(void)
{
	int vl;

	asm ("rvdl %0, #1" : "=r" (vl));

	return vl;
}

would also work.

&rdvl_sve would not be the same in different translation units, but I
don't think the tests care about that(?)

[...]

Cheers
---Dave
Mark Brown July 28, 2021, 10:20 a.m. UTC | #2
On Wed, Jul 28, 2021 at 10:41:30AM +0100, Dave Martin wrote:
> On Tue, Jul 27, 2021 at 07:06:47PM +0100, Mark Brown wrote:

> > SVE provides an instruction RDVL which reports the currently configured

> > vector length. In order to validate that our vector length configuration

> > interfaces are working correctly without having to build the C code for


> > +.globl rdvl_sve

> > +rdvl_sve:

> > +	rdvl	x0, #1

> > +	ret

> 

> This works, but can we use an ACLE intrinsic for this?  I'm pretty GCC

> and LLVM have been up to date with that stuff for some time, though

> you'd have to check with the compiler folks.


If we put SVE into C source files we need to build the C code with SVE
support enabled, I felt it was safer to avoid any possibility that we
might get some interference with the tests due to interactions with SVE
code generated by the compiler.  It should be fine, but it's even easier
to not have to think about it at all.
Dave Martin July 28, 2021, 10:45 a.m. UTC | #3
On Wed, Jul 28, 2021 at 11:20:35AM +0100, Mark Brown wrote:
> On Wed, Jul 28, 2021 at 10:41:30AM +0100, Dave Martin wrote:

> > On Tue, Jul 27, 2021 at 07:06:47PM +0100, Mark Brown wrote:

> > > SVE provides an instruction RDVL which reports the currently configured

> > > vector length. In order to validate that our vector length configuration

> > > interfaces are working correctly without having to build the C code for

> 

> > > +.globl rdvl_sve

> > > +rdvl_sve:

> > > +	rdvl	x0, #1

> > > +	ret

> > 

> > This works, but can we use an ACLE intrinsic for this?  I'm pretty GCC

> > and LLVM have been up to date with that stuff for some time, though

> > you'd have to check with the compiler folks.

> 

> If we put SVE into C source files we need to build the C code with SVE

> support enabled, I felt it was safer to avoid any possibility that we

> might get some interference with the tests due to interactions with SVE

> code generated by the compiler.  It should be fine, but it's even easier

> to not have to think about it at all.


Good point, stick with the out-of-line asm in that case.

(Also saves having to find out about the intrinsics!)

Cheers
---Dave
diff mbox series

Patch

diff --git a/tools/testing/selftests/arm64/fp/.gitignore b/tools/testing/selftests/arm64/fp/.gitignore
index d66f76d2a650..6b53a7b60fee 100644
--- a/tools/testing/selftests/arm64/fp/.gitignore
+++ b/tools/testing/selftests/arm64/fp/.gitignore
@@ -1,4 +1,5 @@ 
 fpsimd-test
+rdvl-sve
 sve-probe-vls
 sve-ptrace
 sve-test
diff --git a/tools/testing/selftests/arm64/fp/Makefile b/tools/testing/selftests/arm64/fp/Makefile
index a57009d3a0dc..ed62e7003b96 100644
--- a/tools/testing/selftests/arm64/fp/Makefile
+++ b/tools/testing/selftests/arm64/fp/Makefile
@@ -2,12 +2,16 @@ 
 
 CFLAGS += -I../../../../../usr/include/
 TEST_GEN_PROGS := sve-ptrace sve-probe-vls
-TEST_PROGS_EXTENDED := fpsimd-test fpsimd-stress sve-test sve-stress vlset
+TEST_PROGS_EXTENDED := fpsimd-test fpsimd-stress \
+	rdvl-sve \
+	sve-test sve-stress \
+	vlset
 
 all: $(TEST_GEN_PROGS) $(TEST_PROGS_EXTENDED)
 
 fpsimd-test: fpsimd-test.o
 	$(CC) -nostdlib $^ -o $@
+rdvl-sve: rdvl-sve.o rdvl.o
 sve-ptrace: sve-ptrace.o sve-ptrace-asm.o
 sve-probe-vls: sve-probe-vls.o
 sve-test: sve-test.o
diff --git a/tools/testing/selftests/arm64/fp/rdvl-sve.c b/tools/testing/selftests/arm64/fp/rdvl-sve.c
new file mode 100644
index 000000000000..7f8a13a18f5d
--- /dev/null
+++ b/tools/testing/selftests/arm64/fp/rdvl-sve.c
@@ -0,0 +1,14 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <stdio.h>
+
+#include "rdvl.h"
+
+int main(void)
+{
+	int vl = rdvl_sve();
+
+	printf("%d\n", vl);
+
+	return 0;
+}
diff --git a/tools/testing/selftests/arm64/fp/rdvl.S b/tools/testing/selftests/arm64/fp/rdvl.S
new file mode 100644
index 000000000000..6e76dd720b87
--- /dev/null
+++ b/tools/testing/selftests/arm64/fp/rdvl.S
@@ -0,0 +1,9 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2021 ARM Limited.
+
+.arch_extension sve
+
+.globl rdvl_sve
+rdvl_sve:
+	rdvl	x0, #1
+	ret
diff --git a/tools/testing/selftests/arm64/fp/rdvl.h b/tools/testing/selftests/arm64/fp/rdvl.h
new file mode 100644
index 000000000000..7c9d953fc9e7
--- /dev/null
+++ b/tools/testing/selftests/arm64/fp/rdvl.h
@@ -0,0 +1,8 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef RDVL_H
+#define RDVL_H
+
+int rdvl_sve(void);
+
+#endif