diff options
| -rw-r--r-- | sysdeps/aarch64/Makefile | 3 | ||||
| -rw-r--r-- | sysdeps/aarch64/__alloc_gcs.c | 63 | ||||
| -rw-r--r-- | sysdeps/aarch64/aarch64-gcs.h | 28 |
3 files changed, 93 insertions, 1 deletions
diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile index 7447960..4b7f8a5 100644 --- a/sysdeps/aarch64/Makefile +++ b/sysdeps/aarch64/Makefile @@ -71,7 +71,8 @@ sysdep_headers += sys/ifunc.h sysdep_routines += \ __mtag_tag_zero_region \ __mtag_tag_region \ - __arm_za_disable + __arm_za_disable \ + __alloc_gcs tests += \ tst-sme-jmp diff --git a/sysdeps/aarch64/__alloc_gcs.c b/sysdeps/aarch64/__alloc_gcs.c new file mode 100644 index 0000000..e70b459 --- /dev/null +++ b/sysdeps/aarch64/__alloc_gcs.c @@ -0,0 +1,63 @@ +/* AArch64 GCS allocation. + Copyright (C) 2024-2025 Free Software Foundation, Inc. + + 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 + <https://www.gnu.org/licenses/>. */ + +#include <sysdep.h> +#include <unistd.h> +#include <sys/mman.h> + +#ifndef SHADOW_STACK_SET_TOKEN +# define SHADOW_STACK_SET_TOKEN (1UL << 0) +# define SHADOW_STACK_SET_MARKER (1UL << 1) +#endif + +static void * +map_shadow_stack (void *addr, size_t size, unsigned long flags) +{ + return (void *) INLINE_SYSCALL_CALL (map_shadow_stack, addr, size, flags); +} + +#define GCS_MAX_SIZE (1UL << 31) +#define GCS_ALTSTACK_RESERVE 160 + +void * +__alloc_gcs (size_t stack_size, void **ss_base, size_t *ss_size) +{ + size_t size = (stack_size / 2 + GCS_ALTSTACK_RESERVE) & -8UL; + if (size > GCS_MAX_SIZE) + size = GCS_MAX_SIZE; + + unsigned long flags = SHADOW_STACK_SET_MARKER | SHADOW_STACK_SET_TOKEN; + void *base = map_shadow_stack (NULL, size, flags); + if (base == MAP_FAILED) + return NULL; + + *ss_base = base; + *ss_size = size; + + uint64_t *gcsp = (uint64_t *) ((char *) base + size); + /* Skip end of GCS token. */ + gcsp--; + /* Verify GCS cap token. */ + gcsp--; + if (((uint64_t)gcsp & 0xfffffffffffff000) + 1 != *gcsp) + { + __munmap (base, size); + return NULL; + } + /* Return the target GCS pointer for context switch. */ + return gcsp + 1; +} diff --git a/sysdeps/aarch64/aarch64-gcs.h b/sysdeps/aarch64/aarch64-gcs.h new file mode 100644 index 0000000..162ef18 --- /dev/null +++ b/sysdeps/aarch64/aarch64-gcs.h @@ -0,0 +1,28 @@ +/* AArch64 GCS (Guarded Control Stack) declarations. + This file is part of the GNU C Library. + Copyright (C) 2024-2025 Free Software Foundation, Inc. + Copyright The GNU Toolchain Authors. + + 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 + <https://www.gnu.org/licenses/>. */ + +#ifndef _AARCH64_GCS_H +#define _AARCH64_GCS_H + +#include <stddef.h> +#include <stdbool.h> + +void *__alloc_gcs (size_t, void **, size_t *) attribute_hidden; + +#endif |