diff options
Diffstat (limited to 'src/3rdparty/pcre2/src/sljit/allocator_src/sljitWXExecAllocatorPosix.c')
| -rw-r--r-- | src/3rdparty/pcre2/src/sljit/allocator_src/sljitWXExecAllocatorPosix.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/src/3rdparty/pcre2/src/sljit/allocator_src/sljitWXExecAllocatorPosix.c b/src/3rdparty/pcre2/src/sljit/allocator_src/sljitWXExecAllocatorPosix.c new file mode 100644 index 0000000000..36d301434a --- /dev/null +++ b/src/3rdparty/pcre2/src/sljit/allocator_src/sljitWXExecAllocatorPosix.c @@ -0,0 +1,141 @@ +/* + * Stack-less Just-In-Time compiler + * + * Copyright Zoltan Herczeg (hzmester@freemail.hu). All rights reserved. + * + * Redistribution and use in source and binary forms, with or without modification, are + * permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, this list of + * conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright notice, this list + * of conditions and the following disclaimer in the documentation and/or other materials + * provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) AND CONTRIBUTORS ``AS IS'' AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT + * SHALL THE COPYRIGHT HOLDER(S) OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED + * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR + * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/* + This file contains a simple W^X executable memory allocator + + In *NIX, MAP_ANON is required (that is considered a feature) so make + sure to set the right availability macros for your system or the code + will fail to build. + + If your system doesn't support mapping of anonymous pages (ex: IRIX) it + is also likely that it doesn't need this allocator and should be using + the standard one instead. + + It allocates a separate map for each code block and may waste a lot of + memory, because whatever was requested, will be rounded up to the page + size (minimum 4KB, but could be even bigger). + + It changes the page permissions (RW <-> RX) as needed and therefore, if you + will be updating the code after it has been generated, need to make sure to + block any concurrent execution, or could result in a SIGBUS, that could + even manifest itself at a different address than the one that was being + modified. + + Only use if you are unable to use the regular allocator because of security + restrictions and adding exceptions to your application or the system are + not possible. +*/ + +#include <sys/types.h> +#include <sys/mman.h> + +#define SLJIT_UPDATE_WX_FLAGS(from, to, enable_exec) \ + sljit_update_wx_flags((from), (to), (enable_exec)) + +#if !(defined SLJIT_SINGLE_THREADED && SLJIT_SINGLE_THREADED) +#include <pthread.h> +#define SLJIT_SE_LOCK() pthread_mutex_lock(&se_lock) +#define SLJIT_SE_UNLOCK() pthread_mutex_unlock(&se_lock) +#else +#define SLJIT_SE_LOCK() +#define SLJIT_SE_UNLOCK() +#endif /* !SLJIT_SINGLE_THREADED */ + +#define SLJIT_WX_IS_BLOCK(ptr, size) generic_check_is_wx_block(ptr, size) + +static SLJIT_INLINE int generic_check_is_wx_block(void *ptr, sljit_uw size) +{ + if (SLJIT_LIKELY(!mprotect(ptr, size, PROT_EXEC))) + return !!mprotect(ptr, size, PROT_READ | PROT_WRITE); + + return 1; +} + +SLJIT_API_FUNC_ATTRIBUTE void* sljit_malloc_exec(sljit_uw size) +{ +#if !(defined SLJIT_SINGLE_THREADED && SLJIT_SINGLE_THREADED) + static pthread_mutex_t se_lock = PTHREAD_MUTEX_INITIALIZER; +#endif + static int wx_block = -1; + int prot = PROT_READ | PROT_WRITE; + sljit_uw* ptr; + + if (SLJIT_UNLIKELY(wx_block > 0)) + return NULL; + +#ifdef PROT_MAX + prot |= PROT_MAX(PROT_READ | PROT_WRITE | PROT_EXEC); +#endif + + size += sizeof(sljit_uw); + ptr = (sljit_uw*)mmap(NULL, size, prot, MAP_PRIVATE | MAP_ANON, -1, 0); + + if (ptr == MAP_FAILED) + return NULL; + + if (SLJIT_UNLIKELY(wx_block < 0)) { + SLJIT_SE_LOCK(); + wx_block = SLJIT_WX_IS_BLOCK(ptr, size); + SLJIT_SE_UNLOCK(); + if (SLJIT_UNLIKELY(wx_block)) { + munmap((void *)ptr, size); + return NULL; + } + } + + *ptr++ = size; + return ptr; +} + +#undef SLJIT_SE_UNLOCK +#undef SLJIT_SE_LOCK + +SLJIT_API_FUNC_ATTRIBUTE void sljit_free_exec(void* ptr) +{ + sljit_uw *start_ptr = ((sljit_uw*)ptr) - 1; + munmap((void*)start_ptr, *start_ptr); +} + +static void sljit_update_wx_flags(void *from, void *to, int enable_exec) +{ + sljit_uw page_mask = (sljit_uw)get_page_alignment(); + sljit_uw start = (sljit_uw)from; + sljit_uw end = (sljit_uw)to; + int prot = PROT_READ | (enable_exec ? PROT_EXEC : PROT_WRITE); + + SLJIT_ASSERT(start < end); + + start &= ~page_mask; + end = (end + page_mask) & ~page_mask; + + mprotect((void*)start, end - start, prot); +} + +SLJIT_API_FUNC_ATTRIBUTE void sljit_free_unused_memory_exec(void) +{ + /* This allocator does not keep unused memory for future allocations. */ +} |