allocate runtime ics using mmap (with PROT_EXEC) so valgrind doesn't die horribly

src/runtime/ics.cpp

@@ -14,6 +14,8 @@
 
 #include "runtime/ics.h"
 
+#include <sys/mman.h>
+
 #include "asm_writing/icinfo.h"
 #include "asm_writing/rewriter.h"
 #include "codegen/compvars.h"
@@ -26,6 +28,8 @@
 #include "core/stats.h"
 #include "core/types.h"
 
+#define PAGE_SIZE 4096
+
 namespace pyston {
 
 // I am not sure if we should use the equivalent of -fomit-frame-pointer for these trampolines.
@@ -163,7 +167,9 @@ static void writeTrivialEhFrame(void* eh_frame_addr, void* func_addr, uint64_t f
 
 void EHFrameManager::writeAndRegister(void* func_addr, uint64_t func_size) {
     assert(eh_frame_addr == NULL);
-    eh_frame_addr = malloc(EH_FRAME_SIZE);
+    eh_frame_addr = mmap(NULL, (EH_FRAME_SIZE + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1), PROT_READ | PROT_WRITE,
+                         MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    RELEASE_ASSERT(eh_frame_addr != MAP_FAILED, "");
     writeTrivialEhFrame(eh_frame_addr, func_addr, func_size);
     // (EH_FRAME_SIZE - 4) to omit the 4-byte null terminator, otherwise we trip an assert in parseEhFrame.
     // TODO: can we omit the terminator in general?
@@ -174,7 +180,7 @@ void EHFrameManager::writeAndRegister(void* func_addr, uint64_t func_size) {
 EHFrameManager::~EHFrameManager() {
     if (eh_frame_addr) {
         deregisterEHFrames((uint8_t*)eh_frame_addr, (uint64_t)eh_frame_addr, EH_FRAME_SIZE);
-        free(eh_frame_addr);
+        munmap(eh_frame_addr, (EH_FRAME_SIZE + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1));
     }
 }
 
@@ -227,8 +233,11 @@ RuntimeIC::RuntimeIC(void* func_addr, int num_slots, int slot_size) {
         static const int CALL_SIZE = 13;
 
         int patchable_size = num_slots * slot_size;
-        int total_size = PROLOGUE_SIZE + patchable_size + CALL_SIZE + EPILOGUE_SIZE;
-        addr = malloc(total_size);
+        total_size = PROLOGUE_SIZE + patchable_size + CALL_SIZE + EPILOGUE_SIZE;
+
+        addr = mmap(NULL, (total_size + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1), PROT_READ | PROT_WRITE | PROT_EXEC,
+                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+        RELEASE_ASSERT(addr != MAP_FAILED, "");
 
         // printf("Allocated runtime IC at %p\n", addr);
 
@@ -285,7 +294,7 @@ RuntimeIC::RuntimeIC(void* func_addr, int num_slots, int slot_size) {
 RuntimeIC::~RuntimeIC() {
     if (ENABLE_RUNTIME_ICS) {
         deregisterCompiledPatchpoint(icinfo.get());
-        free(addr);
+        munmap(addr, total_size);
     } else {
     }
 }

src/runtime/ics.h

@@ -35,6 +35,7 @@ public:
 class RuntimeIC {
 private:
     void* addr;
+    size_t total_size;
     EHFrameManager eh_frame;
 
     std::unique_ptr<ICInfo> icinfo;