added b/bl handling for arm64

Author: Antibioticss

src/tinyhook.c

@@ -102,6 +102,13 @@ static inline void save_header(void **src, void **dst, int min_len) {
                 }
             }
         }
+        else if (((insn ^ 0x14000000) & 0xfc000000) == 0 || ((insn ^ 0x94000000) & 0xfc000000) == 0) {
+            // b or bl
+            bool link = insn >> 31;
+            int32_t imm26 = (int32_t)(insn << 6) >> 6; // sign extend
+            void *addr = *src + (imm26 << 2);
+            *dst += calc_jump(*dst, *dst, addr, link);
+        }
         else {
             *(uint32_t *)*dst = insn;
             *dst += 4;

test/hook/Makefile

@@ -1,7 +1,7 @@
 ARCH ?= $(shell uname -m)
 
 CC := clang -arch $(ARCH)
-CFLAGS := -O0 -Wall -g # -fsanitize=address
+CFLAGS := -Os -Wall -g # -fsanitize=address
 OBJCFLAGS := -framework Cocoa
 
 OBJ := example.o main.o

test/hook/example.c

@@ -27,8 +27,10 @@ int printf_interpose(const char *format, ...) {
     return res;
 }
 
+int (*orig_add)(int a, int b);
 int fake_add(int a, int b) {
-    fprintf(stderr, "=== calling fake_add with: %d, %d\n", a, b);
+    fprintf(stderr, "=== calling add with: %d, %d\n", a, b);
+    fprintf(stderr, "=== the return value is: %d\n", orig_add(a, b));
     return -1;
 }
 
@@ -48,7 +50,7 @@ __attribute__((constructor(0))) int load() {
     // hook a function by symbol (in the SYMTAB)
     void *func_add = symtbl_solve(0, "_add");
     fprintf(stderr, "=== add() address: %p\n", func_add);
-    tiny_hook(func_add, fake_add, NULL);
+    tiny_hook(func_add, fake_add, &orig_add);
 
     // hook system function
     fprintf(stderr, "=== Hooking printf\n");

test/hook/main.c

@@ -1,9 +1,17 @@
 #include <stdio.h>
 
-int add(int a, int b) {
+int add2(int a, int b) {
     return a + b;
 }
 
+__attribute__((naked)) int add(int a, int b) {
+#ifdef __arm64__
+    asm volatile("b _add2");
+#elif __x86_64__
+    asm volatile("call _add2");
+#endif
+}
+
 int main() {
     int res = add(1, 2);
     printf("1 + 2 = %d\n", res);