mirror of
https://sourceware.org/git/glibc.git
synced 2025-08-08 17:42:12 +03:00
eeedfc2f74
No functional change here, just a small refactoring to simplify using __alloc_gcs() for allocating shadow stacks. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
71 lines
2.0 KiB
C
71 lines
2.0 KiB
C
/* 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 "aarch64-gcs.h"
|
|
|
|
#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, struct gcs_record *gcs)
|
|
{
|
|
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;
|
|
|
|
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;
|
|
}
|
|
|
|
if (gcs != NULL)
|
|
{
|
|
gcs->gcs_base = base;
|
|
gcs->gcs_token = gcsp;
|
|
gcs->gcs_size = size;
|
|
}
|
|
|
|
/* Return the target GCS pointer for context switch. */
|
|
return gcsp + 1;
|
|
}
|