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Date:   Mon, 7 Aug 2023 10:53:32 -0700
From:   Charlie Jenkins <charlie@rivosinc.com>
To:     Alexandre Ghiti <alex@ghiti.fr>
Cc:     linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        conor@kernel.org, paul.walmsley@sifive.com, palmer@rivosinc.com,
        aou@eecs.berkeley.edu, anup@brainfault.org,
        konstantin@linuxfoundation.org, linux-doc@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-mm@kvack.org,
        mick@ics.forth.gr, jrtc27@jrtc27.com, rdunlap@infradead.org,
        alexghiti@rivosinc.com
Subject: Re: [PATCH v8 2/4] RISC-V: mm: Add tests for RISC-V mm
Message-ID: <ZNEvnBaf0P1owNNU@ghost>
References: <20230727212647.4182407-1-charlie@rivosinc.com>
 <20230727212647.4182407-3-charlie@rivosinc.com>
 <a96afa52-14aa-28f8-d4e5-34bbd3e400ef@ghiti.fr>
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On Sun, Aug 06, 2023 at 12:06:49PM +0200, Alexandre Ghiti wrote:
> 
> On 27/07/2023 23:26, Charlie Jenkins wrote:
> > Add tests that enforce mmap hint address behavior. mmap should default
> > to sv48. mmap will provide an address at the highest address space that
> > can fit into the hint address, unless the hint address is less than sv39
> > and not 0, then it will return a sv39 address.
> > 
> > These tests are split into two files: mmap_default.c and mmap_bottomup.c
> > because a new process must be exec'd in order to change the mmap layout.
> > The run_mmap.sh script sets the stack to be unlimited for the
> > mmap_bottomup.c test which triggers a bottomup layout.
> > 
> > Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
> > ---
> >   tools/testing/selftests/riscv/Makefile        |  2 +-
> >   tools/testing/selftests/riscv/mm/.gitignore   |  2 +
> >   tools/testing/selftests/riscv/mm/Makefile     | 15 +++++
> >   .../riscv/mm/testcases/mmap_bottomup.c        | 35 ++++++++++
> >   .../riscv/mm/testcases/mmap_default.c         | 35 ++++++++++
> >   .../selftests/riscv/mm/testcases/mmap_test.h  | 64 +++++++++++++++++++
> >   .../selftests/riscv/mm/testcases/run_mmap.sh  | 12 ++++
> >   7 files changed, 164 insertions(+), 1 deletion(-)
> >   create mode 100644 tools/testing/selftests/riscv/mm/.gitignore
> >   create mode 100644 tools/testing/selftests/riscv/mm/Makefile
> >   create mode 100644 tools/testing/selftests/riscv/mm/testcases/mmap_bottomup.c
> >   create mode 100644 tools/testing/selftests/riscv/mm/testcases/mmap_default.c
> >   create mode 100644 tools/testing/selftests/riscv/mm/testcases/mmap_test.h
> >   create mode 100755 tools/testing/selftests/riscv/mm/testcases/run_mmap.sh
> > 
> > diff --git a/tools/testing/selftests/riscv/Makefile b/tools/testing/selftests/riscv/Makefile
> > index f4b3d5c9af5b..4a9ff515a3a0 100644
> > --- a/tools/testing/selftests/riscv/Makefile
> > +++ b/tools/testing/selftests/riscv/Makefile
> > @@ -5,7 +5,7 @@
> >   ARCH ?= $(shell uname -m 2>/dev/null || echo not)
> >   ifneq (,$(filter $(ARCH),riscv))
> > -RISCV_SUBTARGETS ?= hwprobe vector
> > +RISCV_SUBTARGETS ?= hwprobe vector mm
> >   else
> >   RISCV_SUBTARGETS :=
> >   endif
> > diff --git a/tools/testing/selftests/riscv/mm/.gitignore b/tools/testing/selftests/riscv/mm/.gitignore
> > new file mode 100644
> > index 000000000000..5c2c57cb950c
> > --- /dev/null
> > +++ b/tools/testing/selftests/riscv/mm/.gitignore
> > @@ -0,0 +1,2 @@
> > +mmap_bottomup
> > +mmap_default
> > diff --git a/tools/testing/selftests/riscv/mm/Makefile b/tools/testing/selftests/riscv/mm/Makefile
> > new file mode 100644
> > index 000000000000..11e0f0568923
> > --- /dev/null
> > +++ b/tools/testing/selftests/riscv/mm/Makefile
> > @@ -0,0 +1,15 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (C) 2021 ARM Limited
> > +# Originally tools/testing/arm64/abi/Makefile
> > +
> > +# Additional include paths needed by kselftest.h and local headers
> > +CFLAGS += -D_GNU_SOURCE -std=gnu99 -I.
> > +
> > +TEST_GEN_FILES := testcases/mmap_default testcases/mmap_bottomup
> > +
> > +TEST_PROGS := testcases/run_mmap.sh
> > +
> > +include ../../lib.mk
> > +
> > +$(OUTPUT)/mm: testcases/mmap_default.c testcases/mmap_bottomup.c testcases/mmap_tests.h
> > +	$(CC) -o$@ $(CFLAGS) $(LDFLAGS) $^
> > diff --git a/tools/testing/selftests/riscv/mm/testcases/mmap_bottomup.c b/tools/testing/selftests/riscv/mm/testcases/mmap_bottomup.c
> > new file mode 100644
> > index 000000000000..b29379f7e478
> > --- /dev/null
> > +++ b/tools/testing/selftests/riscv/mm/testcases/mmap_bottomup.c
> > @@ -0,0 +1,35 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +#include <sys/mman.h>
> > +#include <testcases/mmap_test.h>
> > +
> > +#include "../../kselftest_harness.h"
> > +
> > +TEST(infinite_rlimit)
> > +{
> > +// Only works on 64 bit
> > +#if __riscv_xlen == 64
> > +	struct addresses mmap_addresses;
> > +
> > +	EXPECT_EQ(BOTTOM_UP, memory_layout());
> > +
> > +	do_mmaps(&mmap_addresses);
> > +
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.no_hint);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_37_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_38_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_46_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_47_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_55_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_56_addr);
> > +
> > +	EXPECT_GT(1UL << 47, (unsigned long)mmap_addresses.no_hint);
> 
> 
> This test ^ will only work on sv48+ systems, if launched on a sv39 system,
> it will fail
>
I may be missing something, but why would this test fail? It may not be
particularily useful since the addresses will always be in the sv39
address space, but it shouldn't fail. I have tested in QEMU and it
passes. This tests if 1UL << 47 is greater than the returned mmap address
which will always be true.
> 
> 
> > +	EXPECT_GT(1UL << 38, (unsigned long)mmap_addresses.on_37_addr);
> > +	EXPECT_GT(1UL << 38, (unsigned long)mmap_addresses.on_38_addr);
> > +	EXPECT_GT(1UL << 38, (unsigned long)mmap_addresses.on_46_addr);
> > +	EXPECT_GT(1UL << 47, (unsigned long)mmap_addresses.on_47_addr);
> > +	EXPECT_GT(1UL << 47, (unsigned long)mmap_addresses.on_55_addr);
> > +	EXPECT_GT(1UL << 56, (unsigned long)mmap_addresses.on_56_addr);
> > +#endif
> > +}
> > +
> > +TEST_HARNESS_MAIN
> > diff --git a/tools/testing/selftests/riscv/mm/testcases/mmap_default.c b/tools/testing/selftests/riscv/mm/testcases/mmap_default.c
> > new file mode 100644
> > index 000000000000..d1accb91b726
> > --- /dev/null
> > +++ b/tools/testing/selftests/riscv/mm/testcases/mmap_default.c
> > @@ -0,0 +1,35 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +#include <sys/mman.h>
> > +#include <testcases/mmap_test.h>
> > +
> > +#include "../../kselftest_harness.h"
> > +
> > +TEST(default_rlimit)
> > +{
> > +// Only works on 64 bit
> > +#if __riscv_xlen == 64
> > +	struct addresses mmap_addresses;
> > +
> > +	EXPECT_EQ(TOP_DOWN, memory_layout());
> > +
> > +	do_mmaps(&mmap_addresses);
> > +
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.no_hint);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_37_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_38_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_46_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_47_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_55_addr);
> > +	EXPECT_NE(MAP_FAILED, mmap_addresses.on_56_addr);
> > +
> > +	EXPECT_GT(1UL << 47, (unsigned long)mmap_addresses.no_hint);
> > +	EXPECT_GT(1UL << 38, (unsigned long)mmap_addresses.on_37_addr);
> > +	EXPECT_GT(1UL << 38, (unsigned long)mmap_addresses.on_38_addr);
> > +	EXPECT_GT(1UL << 38, (unsigned long)mmap_addresses.on_46_addr);
> > +	EXPECT_GT(1UL << 47, (unsigned long)mmap_addresses.on_47_addr);
> > +	EXPECT_GT(1UL << 47, (unsigned long)mmap_addresses.on_55_addr);
> > +	EXPECT_GT(1UL << 56, (unsigned long)mmap_addresses.on_56_addr);
> > +#endif
> > +}
> > +
> > +TEST_HARNESS_MAIN
> > diff --git a/tools/testing/selftests/riscv/mm/testcases/mmap_test.h b/tools/testing/selftests/riscv/mm/testcases/mmap_test.h
> > new file mode 100644
> > index 000000000000..98a892de5d19
> > --- /dev/null
> > +++ b/tools/testing/selftests/riscv/mm/testcases/mmap_test.h
> > @@ -0,0 +1,64 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +#ifndef _TESTCASES_MMAP_TEST_H
> > +#define _TESTCASES_MMAP_TEST_H
> > +#include <sys/mman.h>
> > +#include <sys/resource.h>
> > +#include <stddef.h>
> > +
> > +#define TOP_DOWN 0
> > +#define BOTTOM_UP 1
> > +
> > +struct addresses {
> > +	int *no_hint;
> > +	int *on_37_addr;
> > +	int *on_38_addr;
> > +	int *on_46_addr;
> > +	int *on_47_addr;
> > +	int *on_55_addr;
> > +	int *on_56_addr;
> > +};
> > +
> > +void do_mmaps(struct addresses *mmap_addresses)
> 
> 
> I would static inline this function definition since you are in a header
> file.
> 
> 
> > +{
> > +	/*
> > +	 * Place all of the hint addresses on the boundaries of mmap
> > +	 * sv39, sv48, sv57
> > +	 * User addresses end at 1<<38, 1<<47, 1<<56 respectively
> > +	 */
> > +	void *on_37_bits = (void *)(1UL << 37);
> > +	void *on_38_bits = (void *)(1UL << 38);
> > +	void *on_46_bits = (void *)(1UL << 46);
> > +	void *on_47_bits = (void *)(1UL << 47);
> > +	void *on_55_bits = (void *)(1UL << 55);
> > +	void *on_56_bits = (void *)(1UL << 56);
> > +
> > +	int prot = PROT_READ | PROT_WRITE;
> > +	int flags = MAP_PRIVATE | MAP_ANONYMOUS;
> > +
> > +	mmap_addresses->no_hint =
> > +		mmap(NULL, 5 * sizeof(int), prot, flags, 0, 0);
> > +	mmap_addresses->on_37_addr =
> > +		mmap(on_37_bits, 5 * sizeof(int), prot, flags, 0, 0);
> > +	mmap_addresses->on_38_addr =
> > +		mmap(on_38_bits, 5 * sizeof(int), prot, flags, 0, 0);
> > +	mmap_addresses->on_46_addr =
> > +		mmap(on_46_bits, 5 * sizeof(int), prot, flags, 0, 0);
> > +	mmap_addresses->on_47_addr =
> > +		mmap(on_47_bits, 5 * sizeof(int), prot, flags, 0, 0);
> > +	mmap_addresses->on_55_addr =
> > +		mmap(on_55_bits, 5 * sizeof(int), prot, flags, 0, 0);
> > +	mmap_addresses->on_56_addr =
> > +		mmap(on_56_bits, 5 * sizeof(int), prot, flags, 0, 0);
> > +}
> > +
> > +int memory_layout(void)
> > +{
> > +	int prot = PROT_READ | PROT_WRITE;
> > +	int flags = MAP_PRIVATE | MAP_ANONYMOUS;
> > +
> > +	void *value1 = mmap(NULL, sizeof(int), prot, flags, 0, 0);
> > +	void *value2 = mmap(NULL, sizeof(int), prot, flags, 0, 0);
> > +
> > +	return value2 > value1;
> > +}
> > +#endif /* _TESTCASES_MMAP_TEST_H */
> > diff --git a/tools/testing/selftests/riscv/mm/testcases/run_mmap.sh b/tools/testing/selftests/riscv/mm/testcases/run_mmap.sh
> > new file mode 100755
> > index 000000000000..ca5ad7c48bad
> > --- /dev/null
> > +++ b/tools/testing/selftests/riscv/mm/testcases/run_mmap.sh
> > @@ -0,0 +1,12 @@
> > +#!/bin/sh
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +original_stack_limit=$(ulimit -s)
> > +
> > +./mmap_default
> > +
> > +# Force mmap_bottomup to be ran with bottomup memory due to
> > +# the unlimited stack
> > +ulimit -s unlimited
> > +./mmap_bottomup
> > +ulimit -s $original_stack_limit