Re: [PATCH v15 17/17] selftests, arm64: add a selftest for passing tagged pointers to kernel
On Fri, May 31, 2019 at 04:21:48PM +0200, Andrey Konovalov wrote: > On Wed, May 22, 2019 at 4:16 PM Catalin Marinas > wrote: > > On Mon, May 06, 2019 at 06:31:03PM +0200, Andrey Konovalov wrote: > > > This patch is a part of a series that extends arm64 kernel ABI to allow to > > > pass tagged user pointers (with the top byte set to something else other > > > than 0x00) as syscall arguments. > > > > > > This patch adds a simple test, that calls the uname syscall with a > > > tagged user pointer as an argument. Without the kernel accepting tagged > > > user pointers the test fails with EFAULT. > > > > That's probably sufficient for a simple example. Something we could add > > to Documentation maybe is a small library that can be LD_PRELOAD'ed so > > that you can run a lot more tests like LTP. > > Should I add this into this series, or should this go into Vincenzo's > patchset? If you can tweak the selftest Makefile to build a library and force it with LD_PRELOAD, you can keep it with this patch. It would be easier to extend to other syscall tests, signal handling etc. -- Catalin
Re: [PATCH v15 17/17] selftests, arm64: add a selftest for passing tagged pointers to kernel
On Wed, May 22, 2019 at 4:16 PM Catalin Marinas wrote:
>
> On Mon, May 06, 2019 at 06:31:03PM +0200, Andrey Konovalov wrote:
> > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > pass tagged user pointers (with the top byte set to something else other
> > than 0x00) as syscall arguments.
> >
> > This patch adds a simple test, that calls the uname syscall with a
> > tagged user pointer as an argument. Without the kernel accepting tagged
> > user pointers the test fails with EFAULT.
>
> That's probably sufficient for a simple example. Something we could add
> to Documentation maybe is a small library that can be LD_PRELOAD'ed so
> that you can run a lot more tests like LTP.
Should I add this into this series, or should this go into Vincenzo's patchset?
>
> We could add this to selftests but I think it's too glibc specific.
>
> 8<
> #include
>
> #define TAG_SHIFT (56)
> #define TAG_MASK(0xffUL << TAG_SHIFT)
>
> void *__libc_malloc(size_t size);
> void __libc_free(void *ptr);
> void *__libc_realloc(void *ptr, size_t size);
> void *__libc_calloc(size_t nmemb, size_t size);
>
> static void *tag_ptr(void *ptr)
> {
> unsigned long tag = rand() & 0xff;
> if (!ptr)
> return ptr;
> return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
> }
>
> static void *untag_ptr(void *ptr)
> {
> return (void *)((unsigned long)ptr & ~TAG_MASK);
> }
>
> void *malloc(size_t size)
> {
> return tag_ptr(__libc_malloc(size));
> }
>
> void free(void *ptr)
> {
> __libc_free(untag_ptr(ptr));
> }
>
> void *realloc(void *ptr, size_t size)
> {
> return tag_ptr(__libc_realloc(untag_ptr(ptr), size));
> }
>
> void *calloc(size_t nmemb, size_t size)
> {
> return tag_ptr(__libc_calloc(nmemb, size));
> }
Re: [PATCH v15 17/17] selftests, arm64: add a selftest for passing tagged pointers to kernel
On Mon, May 06, 2019 at 06:31:03PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
>
> This patch adds a simple test, that calls the uname syscall with a
> tagged user pointer as an argument. Without the kernel accepting tagged
> user pointers the test fails with EFAULT.
That's probably sufficient for a simple example. Something we could add
to Documentation maybe is a small library that can be LD_PRELOAD'ed so
that you can run a lot more tests like LTP.
We could add this to selftests but I think it's too glibc specific.
8<
#include
#define TAG_SHIFT (56)
#define TAG_MASK(0xffUL << TAG_SHIFT)
void *__libc_malloc(size_t size);
void __libc_free(void *ptr);
void *__libc_realloc(void *ptr, size_t size);
void *__libc_calloc(size_t nmemb, size_t size);
static void *tag_ptr(void *ptr)
{
unsigned long tag = rand() & 0xff;
if (!ptr)
return ptr;
return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
}
static void *untag_ptr(void *ptr)
{
return (void *)((unsigned long)ptr & ~TAG_MASK);
}
void *malloc(size_t size)
{
return tag_ptr(__libc_malloc(size));
}
void free(void *ptr)
{
__libc_free(untag_ptr(ptr));
}
void *realloc(void *ptr, size_t size)
{
return tag_ptr(__libc_realloc(untag_ptr(ptr), size));
}
void *calloc(size_t nmemb, size_t size)
{
return tag_ptr(__libc_calloc(nmemb, size));
}
[PATCH v15 17/17] selftests, arm64: add a selftest for passing tagged pointers to kernel
This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.
This patch adds a simple test, that calls the uname syscall with a
tagged user pointer as an argument. Without the kernel accepting tagged
user pointers the test fails with EFAULT.
Signed-off-by: Andrey Konovalov
---
tools/testing/selftests/arm64/.gitignore | 1 +
tools/testing/selftests/arm64/Makefile| 11 ++
.../testing/selftests/arm64/run_tags_test.sh | 12 +++
tools/testing/selftests/arm64/tags_test.c | 21 +++
4 files changed, 45 insertions(+)
create mode 100644 tools/testing/selftests/arm64/.gitignore
create mode 100644 tools/testing/selftests/arm64/Makefile
create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh
create mode 100644 tools/testing/selftests/arm64/tags_test.c
diff --git a/tools/testing/selftests/arm64/.gitignore
b/tools/testing/selftests/arm64/.gitignore
new file mode 100644
index ..e8fae8d61ed6
--- /dev/null
+++ b/tools/testing/selftests/arm64/.gitignore
@@ -0,0 +1 @@
+tags_test
diff --git a/tools/testing/selftests/arm64/Makefile
b/tools/testing/selftests/arm64/Makefile
new file mode 100644
index ..a61b2e743e99
--- /dev/null
+++ b/tools/testing/selftests/arm64/Makefile
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0
+
+# ARCH can be overridden by the user for cross compiling
+ARCH ?= $(shell uname -m 2>/dev/null || echo not)
+
+ifneq (,$(filter $(ARCH),aarch64 arm64))
+TEST_GEN_PROGS := tags_test
+TEST_PROGS := run_tags_test.sh
+endif
+
+include ../lib.mk
diff --git a/tools/testing/selftests/arm64/run_tags_test.sh
b/tools/testing/selftests/arm64/run_tags_test.sh
new file mode 100755
index ..745f11379930
--- /dev/null
+++ b/tools/testing/selftests/arm64/run_tags_test.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+echo ""
+echo "running tags test"
+echo ""
+./tags_test
+if [ $? -ne 0 ]; then
+ echo "[FAIL]"
+else
+ echo "[PASS]"
+fi
diff --git a/tools/testing/selftests/arm64/tags_test.c
b/tools/testing/selftests/arm64/tags_test.c
new file mode 100644
index ..2bd1830a7ebe
--- /dev/null
+++ b/tools/testing/selftests/arm64/tags_test.c
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include
+#include
+#include
+#include
+#include
+
+#define SHIFT_TAG(tag) ((uint64_t)(tag) << 56)
+#define SET_TAG(ptr, tag) (((uint64_t)(ptr) & ~SHIFT_TAG(0xff)) | \
+ SHIFT_TAG(tag))
+
+int main(void)
+{
+ struct utsname *ptr = (struct utsname *)malloc(sizeof(*ptr));
+ void *tagged_ptr = (void *)SET_TAG(ptr, 0x42);
+ int err = uname(tagged_ptr);
+
+ free(ptr);
+ return err;
+}
--
2.21.0.1020.gf2820cf01a-goog
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