Revise comments

src/audit_plugin.cc

@@ -1623,8 +1623,7 @@ static int audit_plugin_init(void *p)
 	size_t func_in_plugin = (size_t)trampoline_dummy_func_for_mem;
 	if (func_in_mysqld < INT_MAX && func_in_plugin > INT_MAX)
 	{
-		// When the distance from a hot patch function to trampoline_mem is within 2GB,
+		// See comment about IndirectJump in hot_patch.cc.
-		// the minimum size of hot patching is reduced from 14 to 6.
 		mmap_flags |= MAP_32BIT;
 		use_static_memory = false;
 	}

src/hot_patch.cc

@@ -228,15 +228,20 @@ static bool HookFunction(ULONG_PTR targetFunction, ULONG_PTR newFunction, ULONG_
 #else
 #define ASM_MODE 64
 	enum {
-		// overwrite 14 bytes in targetFunction.
+		// Jump64 overwrites 14 bytes in targetFunction.
-		// jump to newFunction by WriteJump().
+		// This is used when the next two jump types are not available.
 		Jump64,
-		// overwrite 5 bytes in targetFunction.
+		// Jump32 overwrites 5 bytes in targetFunction.
-		// jump to newFunction by WriteJump32().
+		// This is used when mysqld is a Position Independent Executable(PIE).
+		// The mysqld would be loaded near dynamically loaded shared libraries
 		Jump32,
-		// overwrite 5 bytes in targetFunction.
+		// IndirectJump overwrites 5 bytes in targetFunction and uses
-		// jump to a region in trampolineFunction by WriteJump32()
+		// extra 14 bytes in the region of trampolineFunction.
-		// and then jump to newFunction by WriteJump().
+		// This is used when mysqld isn't a Position Independent Executable(PIE).
+		// The mysqld is loaded at the fixed position 0x00400000.
+		// The region of trampolineFunction is located near the mysqld
+		// because it is allocated in audit_plugin_init() with the MAP_32BIT
+		// flag if mysqld isn't a PIE.
 		IndirectJump,
 	} jumpType = Jump64;
 #endif