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author | Ben Cheng <bccheng@google.com> | 2012-10-01 10:30:31 -0700 |
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committer | Ben Cheng <bccheng@google.com> | 2012-10-01 10:30:31 -0700 |
commit | 82bcbebce43f0227f506d75a5b764b6847041bae (patch) | |
tree | fe9f8597b48a430c4daeb5123e3e8eb28e6f9da9 /gcc-4.7/libgcc/enable-execute-stack-mprotect.c | |
parent | 3c052de3bb16ac53b6b6ed659ec7557eb84c7590 (diff) | |
download | toolchain_gcc-82bcbebce43f0227f506d75a5b764b6847041bae.tar.gz toolchain_gcc-82bcbebce43f0227f506d75a5b764b6847041bae.tar.bz2 toolchain_gcc-82bcbebce43f0227f506d75a5b764b6847041bae.zip |
Initial check-in of gcc 4.7.2.
Change-Id: I4a2f5a921c21741a0e18bda986d77e5f1bef0365
Diffstat (limited to 'gcc-4.7/libgcc/enable-execute-stack-mprotect.c')
-rw-r--r-- | gcc-4.7/libgcc/enable-execute-stack-mprotect.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/gcc-4.7/libgcc/enable-execute-stack-mprotect.c b/gcc-4.7/libgcc/enable-execute-stack-mprotect.c new file mode 100644 index 000000000..41b2635ec --- /dev/null +++ b/gcc-4.7/libgcc/enable-execute-stack-mprotect.c @@ -0,0 +1,92 @@ +/* Implement __enable_execute_stack using mprotect(2). + Copyright (C) 2011, 2012 Free Software Foundation, Inc. + + This file is part of GCC. + + GCC is free software; you can redistribute it and/or modify it under + the terms of the GNU General Public License as published by the Free + Software Foundation; either version 3, or (at your option) any later + version. + + GCC 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 General Public License + for more details. + + Under Section 7 of GPL version 3, you are granted additional + permissions described in the GCC Runtime Library Exception, version + 3.1, as published by the Free Software Foundation. + + You should have received a copy of the GNU General Public License and + a copy of the GCC Runtime Library Exception along with this program; + see the files COPYING3 and COPYING.RUNTIME respectively. If not, see + <http://www.gnu.org/licenses/>. */ + +#include <sys/mman.h> +#include <unistd.h> +#include <stdlib.h> + +#define STACK_PROT_RWX (PROT_READ | PROT_WRITE | PROT_EXEC) + +static int need_enable_exec_stack; + +static void check_enabling (void) __attribute__ ((unused)); +extern void __enable_execute_stack (void *); + +#if defined __FreeBSD__ +#include <sys/sysctl.h> + +static void __attribute__ ((constructor)) +check_enabling (void) +{ + int prot = 0; + size_t len = sizeof (prot); + + sysctlbyname ("kern.stackprot", &prot, &len, NULL, 0); + if (prot != STACK_PROT_RWX) + need_enable_exec_stack = 1; +} +#elif defined __sun__ && defined __svr4__ +static void __attribute__ ((constructor)) +check_enabling (void) +{ + int prot = (int) sysconf (_SC_STACK_PROT); + + if (prot != STACK_PROT_RWX) + need_enable_exec_stack = 1; +} +#else +/* There is no way to query the execute permission of the stack, so + we always issue the mprotect() call. */ + +static int need_enable_exec_stack = 1; +#endif + +/* Attempt to turn on access permissions for the stack. Unfortunately it + is not possible to make this namespace-clean.*/ + +void +__enable_execute_stack (void *addr) +{ + if (!need_enable_exec_stack) + return; + else + { + static long size, mask; + + if (size == 0) { + size = getpagesize (); + mask = ~(size - 1); + } + + char *page = (char *) (((long) addr) & mask); + char *end = (char *) + ((((long) (addr + __LIBGCC_TRAMPOLINE_SIZE__)) & mask) + size); + + if (mprotect (page, end - page, STACK_PROT_RWX) < 0) + /* Note that no errors should be emitted by this code; it is + considered dangerous for library calls to send messages to + stdout/stderr. */ + abort (); + } +} |