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use mmap to allocate memory for generated code to be able to set PROT_EXEC

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This commit is contained in:
Ludwig Nussel 2006-03-04 11:14:44 +00:00
parent 87ce505868
commit 39f2e449b6
3 changed files with 49 additions and 50 deletions
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48
code/qcommon/vm_x86.c
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@ -31,6 +31,14 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#include <sys/mman.h> // for PROT_ stuff
#endif
/* need this on NX enabled systems (i386 with PAE kernel or
* noexec32=on x86_64) */
#ifdef __linux__
#define VM_X86_MMAP
#endif
static void VM_Destroy_Compiled(vm_t* self);
/*
eax scratch
@ -1069,34 +1077,40 @@ void VM_Compile( vm_t *vm, vmHeader_t *header ) {
// copy to an exact size buffer on the hunk
vm->codeLength = compiledOfs;
vm->codeBase = Hunk_Alloc( compiledOfs, h_low );
#ifdef VM_X86_MMAP
vm->codeBase = mmap(NULL, compiledOfs, PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
if(vm->codeBase == (void*)-1)
Com_Error(ERR_DROP, "VM_CompileX86: can't mmap memory");
#else
vm->codeBase = malloc(compiledOfs);
#endif
Com_Memcpy( vm->codeBase, buf, compiledOfs );
#ifdef VM_X86_MMAP
if(mprotect(vm->codeBase, compiledOfs, PROT_READ|PROT_EXEC))
Com_Error(ERR_DROP, "VM_CompileX86: mprotect failed");
#endif
Z_Free( buf );
Z_Free( jused );
Com_Printf( "VM file %s compiled to %i bytes of code\n", vm->name, compiledOfs );
vm->destroy = VM_Destroy_Compiled;
// offset all the instruction pointers for the new location
for ( i = 0 ; i < header->instructionCount ; i++ ) {
vm->instructionPointers[i] += (int)vm->codeBase;
}
}
#if 0 // ndef _WIN32
// Must make the newly generated code executable
{
int r;
unsigned long addr;
int psize = getpagesize();
addr = ((int)vm->codeBase & ~(psize-1)) - psize;
r = mprotect((char*)addr, vm->codeLength + (int)vm->codeBase - addr + psize,
PROT_READ | PROT_WRITE | PROT_EXEC );
if (r < 0)
Com_Error( ERR_FATAL, "mprotect failed to change PROT_EXEC" );
}
void VM_Destroy_Compiled(vm_t* self)
{
#ifdef VM_X86_MMAP
munmap(self->codeBase, self->codeLength);
#else
free(self->codeBase);
#endif
}
/*