Repair bounds-checking runtime

On this weekend a thought came to me again that tinycc could be used for
scripting. Only its bounds-checking mode turned out to be broken, which
is a pity because bounds-checking is sometimes handy especially for
quickly written scripts.

Since tinycc is one of those small beautiful things, seldomly happening
in our times, I couldn't resist trying to fix it.

Thanks,
Kirill

* bcheck:
  Now btest pass!
  lib/bcheck: Prevent __bound_local_new / __bound_local_delete from being miscompiled
  lib/bcheck: Prevent libc_malloc/libc_free etc from being miscompiled

1 files changed, 8 insertions, 15 deletions

diff --git a/lib/bcheck.c b/lib/bcheck.c
index 48d7606..5ea2d0b 100644
--- a/lib/bcheck.c
+++ b/lib/bcheck.c
@@ -208,25 +208,11 @@ BOUND_PTR_INDIR(8)
 BOUND_PTR_INDIR(12)
 BOUND_PTR_INDIR(16)
 
-#ifdef __i386__
 /* return the frame pointer of the caller */
 #define GET_CALLER_FP(fp)\
 {\
-    unsigned long *fp1;\
-    __asm__ __volatile__ ("movl %%ebp,%0" :"=g" (fp1));\
-    fp = fp1[0];\
+    fp = (unsigned long)__builtin_frame_address(1);\
 }
-#elif defined(__x86_64__)
-/* TCC always creates %rbp frames also on x86_64, so use them.  */
-#define GET_CALLER_FP(fp)\
-{\
-    unsigned long *fp1;\
-    __asm__ __volatile__ ("movq %%rbp,%0" :"=g" (fp1));\
-    fp = fp1[0];\
-}
-#else
-#error put code to extract the calling frame pointer
-#endif
 
 /* called when entering a function to add all the local regions */
 void FASTCALL __bound_local_new(void *p1) 
@@ -638,6 +624,9 @@ static unsigned long get_region_size(void *p)
 
 /* patched memory functions */
 
+/* force compiler to perform stores coded up to this point */
+#define barrier()   __asm__ __volatile__ ("": : : "memory")
+
 static void install_malloc_hooks(void)
 {
 #ifdef CONFIG_TCC_MALLOC_HOOKS
@@ -649,6 +638,8 @@ static void install_malloc_hooks(void)
     __free_hook = __bound_free;
     __realloc_hook = __bound_realloc;
     __memalign_hook = __bound_memalign;
+
+    barrier();
 #endif
 }
 
@@ -659,6 +650,8 @@ static void restore_malloc_hooks(void)
     __free_hook = saved_free_hook;
     __realloc_hook = saved_realloc_hook;
     __memalign_hook = saved_memalign_hook;
+
+    barrier();
 #endif
 }