[v3,8/8] aarch64: Add aarch64-specific files for memory tagging support
Commit Message
This final patch provides the architecture-specific implementation of
the memory-tagging support hooks for aarch64.
---
sysdeps/aarch64/Makefile | 5 +++
sysdeps/aarch64/__mtag_address_get_tag.S | 31 +++++++++++++
sysdeps/aarch64/__mtag_memset_tag.S | 46 +++++++++++++++++++
sysdeps/aarch64/__mtag_new_tag.S | 38 ++++++++++++++++
sysdeps/aarch64/__mtag_tag_region.S | 44 ++++++++++++++++++
sysdeps/aarch64/libc-mtag.h | 57 ++++++++++++++++++++++++
6 files changed, 221 insertions(+)
create mode 100644 sysdeps/aarch64/__mtag_address_get_tag.S
create mode 100644 sysdeps/aarch64/__mtag_memset_tag.S
create mode 100644 sysdeps/aarch64/__mtag_new_tag.S
create mode 100644 sysdeps/aarch64/__mtag_tag_region.S
create mode 100644 sysdeps/aarch64/libc-mtag.h
Comments
The 11/23/2020 15:42, Richard Earnshaw wrote:
> This final patch provides the architecture-specific implementation of
> the memory-tagging support hooks for aarch64.
...
> diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile
> index d8e06d27b2..2e88fc84a4 100644
> --- a/sysdeps/aarch64/Makefile
> +++ b/sysdeps/aarch64/Makefile
> @@ -40,4 +40,9 @@ endif
>
> ifeq ($(subdir),misc)
> sysdep_headers += sys/ifunc.h
> +sysdep_routines += __mtag_tag_region __mtag_new_tag __mtag_address_get_tag
> +endif
> +
> +ifeq ($(subdir),string)
> +sysdep_routines += __mtag_memset_tag
> endif
this is ok, but i think all can go to misc.
> diff --git a/sysdeps/aarch64/__mtag_address_get_tag.S b/sysdeps/aarch64/__mtag_address_get_tag.S
> new file mode 100644
> index 0000000000..654c9d660c
> --- /dev/null
> +++ b/sysdeps/aarch64/__mtag_address_get_tag.S
> @@ -0,0 +1,31 @@
> +/* Copyright (C) 2020 Free Software Foundation, Inc.
> +
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library. If not, see
> + <http://www.gnu.org/licenses/>. */
> +
> +#include <sysdep.h>
> +
i'd like the content after sysdep.h to be in
#ifdef _LIBC_MTAG
so we don't build unused armv8.5-a code into glibc
(which can cause trouble with old binutils).
> +#define ptr x0
> +
> + .arch armv8.5-a
> + .arch_extension memtag
> +
> +ENTRY (__libc_mtag_address_get_tag)
> +
> + ldg ptr, [ptr]
> + ret
> +END (__libc_mtag_address_get_tag)
> +libc_hidden_builtin_def (__libc_mtag_address_get_tag)
i think we don't need libc_hidden_builtin_def here:
that is only necessary when we make this a public api
(by adding it to a Versions file) but then we need
other changes like libc_hidden_proto on declarations
as well. as long as these are only used from libc.so
no magic is needed.
same for the other functions.
> diff --git a/sysdeps/aarch64/__mtag_memset_tag.S b/sysdeps/aarch64/__mtag_memset_tag.S
> new file mode 100644
> index 0000000000..bc98dc49d2
> --- /dev/null
> +++ b/sysdeps/aarch64/__mtag_memset_tag.S
> @@ -0,0 +1,46 @@
...
> +#include <sysdep.h>
> +/* Use the same register names and assignments as memset. */
> +#include "memset-reg.h"
> +
> + .arch armv8.5-a
> + .arch_extension memtag
> +
> +/* NB, only supported on variants with 64-bit pointers. */
> +
> +/* FIXME: This is a minimal implementation. We could do much better than
> + this for large values of COUNT. */
> +
> +ENTRY_ALIGN(__libc_mtag_memset_with_tag, 6)
this should be plain ENTRY
(which defaults to 2^6 alignment)
same for __libc_mtag_tag_region.
> +
> + and valw, valw, 255
> + orr valw, valw, valw, lsl 8
> + orr valw, valw, valw, lsl 16
> + orr val, val, val, lsl 32
> + mov dst, dstin
> +
> +L(loop):
> + stgp val, val, [dst], #16
> + subs count, count, 16
> + bne L(loop)
> + ldg dstin, [dstin] // Recover the tag created (might be untagged).
i think ldg is not needed: for now we only use
this on PROT_MTE enabled memory.
(calling the function with non-heap memory or
disabling mte on heap memory can be treated as
a bug. this decision can be changed later if
we want to expose public mtag api to user code:
in particular the unwinder for stack tagging
may want to use such api, but we don't need to
design that right now.)
same for __libc_mtag_tag_region.
> + ret
> +END (__libc_mtag_memset_with_tag)
> +libc_hidden_builtin_def (__libc_mtag_memset_with_tag)
> diff --git a/sysdeps/aarch64/__mtag_new_tag.S b/sysdeps/aarch64/__mtag_new_tag.S
> new file mode 100644
> index 0000000000..3a22995e9f
> --- /dev/null
> +++ b/sysdeps/aarch64/__mtag_new_tag.S
> @@ -0,0 +1,38 @@
...
> +#include <sysdep.h>
> +
> + .arch armv8.5-a
> + .arch_extension memtag
> +
> +/* NB, only supported on variants with 64-bit pointers. */
> +
> +/* FIXME: This is a minimal implementation. We could do better than
> + this for larger values of COUNT. */
this fixme is not needed here.
> +
> +#define ptr x0
> +#define xset x1
> +
> +ENTRY(__libc_mtag_new_tag)
> + // Guarantee that the new tag is not the same as now.
> + gmi xset, ptr, xzr
> + irg ptr, ptr, xset
> + ret
> +END (__libc_mtag_new_tag)
> +libc_hidden_builtin_def (__libc_mtag_new_tag)
...
rest looked ok.
@@ -40,4 +40,9 @@ endif
ifeq ($(subdir),misc)
sysdep_headers += sys/ifunc.h
+sysdep_routines += __mtag_tag_region __mtag_new_tag __mtag_address_get_tag
+endif
+
+ifeq ($(subdir),string)
+sysdep_routines += __mtag_memset_tag
endif
new file mode 100644
@@ -0,0 +1,31 @@
+/* Copyright (C) 2020 Free Software Foundation, Inc.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+#define ptr x0
+
+ .arch armv8.5-a
+ .arch_extension memtag
+
+ENTRY (__libc_mtag_address_get_tag)
+
+ ldg ptr, [ptr]
+ ret
+END (__libc_mtag_address_get_tag)
+libc_hidden_builtin_def (__libc_mtag_address_get_tag)
new file mode 100644
@@ -0,0 +1,46 @@
+/* Copyright (C) 2020 Free Software Foundation, Inc.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+/* Use the same register names and assignments as memset. */
+#include "memset-reg.h"
+
+ .arch armv8.5-a
+ .arch_extension memtag
+
+/* NB, only supported on variants with 64-bit pointers. */
+
+/* FIXME: This is a minimal implementation. We could do much better than
+ this for large values of COUNT. */
+
+ENTRY_ALIGN(__libc_mtag_memset_with_tag, 6)
+
+ and valw, valw, 255
+ orr valw, valw, valw, lsl 8
+ orr valw, valw, valw, lsl 16
+ orr val, val, val, lsl 32
+ mov dst, dstin
+
+L(loop):
+ stgp val, val, [dst], #16
+ subs count, count, 16
+ bne L(loop)
+ ldg dstin, [dstin] // Recover the tag created (might be untagged).
+ ret
+END (__libc_mtag_memset_with_tag)
+libc_hidden_builtin_def (__libc_mtag_memset_with_tag)
new file mode 100644
@@ -0,0 +1,38 @@
+/* Copyright (C) 2020 Free Software Foundation, Inc.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+ .arch armv8.5-a
+ .arch_extension memtag
+
+/* NB, only supported on variants with 64-bit pointers. */
+
+/* FIXME: This is a minimal implementation. We could do better than
+ this for larger values of COUNT. */
+
+#define ptr x0
+#define xset x1
+
+ENTRY(__libc_mtag_new_tag)
+ // Guarantee that the new tag is not the same as now.
+ gmi xset, ptr, xzr
+ irg ptr, ptr, xset
+ ret
+END (__libc_mtag_new_tag)
+libc_hidden_builtin_def (__libc_mtag_new_tag)
new file mode 100644
@@ -0,0 +1,44 @@
+/* Copyright (C) 2020 Free Software Foundation, Inc.
+
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+/* Use the same register names and assignments as memset. */
+
+ .arch armv8.5-a
+ .arch_extension memtag
+
+/* NB, only supported on variants with 64-bit pointers. */
+
+/* FIXME: This is a minimal implementation. We could do better than
+ this for larger values of COUNT. */
+
+#define dstin x0
+#define count x1
+#define dst x2
+
+ENTRY_ALIGN(__libc_mtag_tag_region, 6)
+
+ mov dst, dstin
+L(loop):
+ stg dst, [dst], #16
+ subs count, count, 16
+ bne L(loop)
+ ldg dstin, [dstin] // Recover the tag created (might be untagged).
+ ret
+END (__libc_mtag_tag_region)
+libc_hidden_builtin_def (__libc_mtag_tag_region)
new file mode 100644
@@ -0,0 +1,57 @@
+/* libc-internal interface for tagged (colored) memory support.
+ Copyright (C) 2020 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _AARCH64_LIBC_MTAG_H
+#define _AARCH64_LIBC_MTAG_H 1
+
+#ifndef _LIBC_MTAG
+/* Generic bindings for systems that do not support memory tagging. */
+#include_next "libc-mtag.h"
+#else
+
+/* Used to ensure additional alignment when objects need to have distinct
+ tags. */
+#define __MTAG_GRANULE_SIZE 16
+
+/* Non-zero if memory obtained via morecore (sbrk) is not tagged. */
+#define __MTAG_SBRK_UNTAGGED 1
+
+/* Extra flags to pass to mmap to get tagged pages. */
+#define __MTAG_MMAP_FLAGS PROT_MTE
+
+/* Set the tags for a region of memory, which must have size and alignment
+ that are multiples of __MTAG_GRANULE_SIZE. Size cannot be zero.
+ void *__libc_mtag_tag_region (const void *, size_t) */
+void *__libc_mtag_tag_region (void *, size_t);
+
+/* Optimized equivalent to __libc_mtag_tag_region followed by memset. */
+void *__libc_mtag_memset_with_tag(void *, int, size_t);
+
+/* Convert address P to a pointer that is tagged correctly for that
+ location.
+ void *__libc_mtag_address_get_tag (void*) */
+void *__libc_mtag_address_get_tag(void *);
+
+/* Assign a new (random) tag to a pointer P (does not adjust the tag on
+ the memory addressed).
+ void *__libc_mtag_new_tag (void*) */
+void *__libc_mtag_new_tag(void *);
+
+#endif /* _LIBC_MTAG */
+
+#endif /* _AARCH64_LIBC_MTAG_H */