Support platforms in which user space addresses may have the higher bit set

Author: arnaud-lb

Zend/zend_portability.h

@@ -879,4 +879,12 @@ static zend_always_inline uint64_t ZEND_BYTES_SWAP64(uint64_t u)
 # define UINTPTR_WIDTH (CHAR_BITS * sizeof(uintptr_t))
 #endif
 
+#if (defined(__linux__) && defined(__x86_64__)) \
+		|| (defined(ZEND_WIN32) && defined(_M_AMD64))
+/* The kernel reserves the higher part of the address space for itself.
+ * Therefore, we can assume that the higher bit of user space addresses is
+ * never set. */
+# define ZEND_HIGH_HALF_KERNEL
+#endif
+
 #endif /* ZEND_PORTABILITY_H */

Zend/zend_vm_gen.php

@@ -1905,7 +1905,11 @@ function gen_executor($f, $skl, $spec, $kind, $executor_name, $initializer_name)
                             out($f,"# define ZEND_OPCODE_HANDLER_RET const zend_op *\n");
                             out($f,"# define ZEND_VM_TAIL_CALL(call) return call\n");
                             out($f,"# define ZEND_VM_CONTINUE()      return opline\n");
-                            out($f,"# define ZEND_VM_RETURN()        return NULL\n");
+                            out($f,"# ifdef ZEND_HIGH_HALF_KERNEL\n");
+                            out($f,"#  define ZEND_VM_RETURN()        return NULL\n");
+                            out($f,"# else\n");
+                            out($f,"#  define ZEND_VM_RETURN()        return ZEND_VM_ENTER_BIT\n");
+                            out($f,"# endif\n");
                             if ($kind == ZEND_VM_KIND_HYBRID) {
                                 out($f,"# define ZEND_VM_HOT\n");
                             }
@@ -1944,7 +1948,11 @@ function gen_executor($f, $skl, $spec, $kind, $executor_name, $initializer_name)
                             out($f,"# define ZEND_VM_ENTER()           opline = EG(current_execute_data)->opline; ZEND_VM_ENTER_EX()\n");
                             out($f,"# define ZEND_VM_LEAVE()           return  2\n");
                             out($f,"#else\n");
-                            out($f,"# define ZEND_VM_ENTER_BIT         (1ULL<<(UINTPTR_WIDTH-1))\n");
+                            out($f,"# ifdef ZEND_HIGH_HALF_KERNEL\n");
+                            out($f,"#  define ZEND_VM_ENTER_BIT        (1ULL<<(UINTPTR_WIDTH-1))\n");
+                            out($f,"# else\n");
+                            out($f,"#  define ZEND_VM_ENTER_BIT        1ULL\n");
+                            out($f,"# endif\n");
                             out($f,"# define ZEND_VM_ENTER_EX()        return (zend_op*)((uintptr_t)opline | ZEND_VM_ENTER_BIT)\n");
                             out($f,"# define ZEND_VM_ENTER()           execute_data = EG(current_execute_data); LOAD_OPLINE(); ZEND_VM_ENTER_EX()\n");
                             out($f,"# define ZEND_VM_LEAVE()           return (zend_op*)((uintptr_t)opline | ZEND_VM_ENTER_BIT)\n");
@@ -2147,7 +2155,11 @@ function gen_executor($f, $skl, $spec, $kind, $executor_name, $initializer_name)
                             out($f, $m[1]."if (UNEXPECTED(!OPLINE))".$m[3]."\n");
                             out($f,"#else\n");
                             out($f, $m[1]."opline = ((opcode_handler_t)opline->handler)(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU);\n");
-                            out($f, $m[1]."if (UNEXPECTED((intptr_t)OPLINE <= 0))".$m[3]."\n");
+                            out($f, "# ifdef ZEND_HIGH_HALF_KERNEL\n");
+                            out($f, $m[1]."if (UNEXPECTED((intptr_t)opline <= 0))".$m[3]."\n");
+                            out($f, "# else\n");
+                            out($f, $m[1]."if (UNEXPECTED(((uintptr_t)opline & ZEND_VM_ENTER_BIT)))".$m[3]."\n");
+                            out($f, "# endif\n");
                             out($f,"#endif\n");
                             if ($kind == ZEND_VM_KIND_HYBRID) {
                                 out($f,"#endif /* ZEND_VM_KIND != ZEND_VM_KIND_HYBRID */\n");
@@ -2176,8 +2188,8 @@ function gen_executor($f, $skl, $spec, $kind, $executor_name, $initializer_name)
                                 "# endif\n" .
                                 $m[1]."return;\n" .
                                 "#else\n" .
-                                $m[1]."if (EXPECTED(opline != NULL && (uintptr_t)opline != ZEND_VM_ENTER_BIT)) {\n" .
-                                $m[1]."\topline = (zend_op*)((uintptr_t)opline & ~ZEND_VM_ENTER_BIT);\n".
+                                $m[1]."opline = (const zend_op*)((uintptr_t)opline & ~ZEND_VM_ENTER_BIT);\n".
+                                $m[1]."if (EXPECTED(opline != NULL)) {\n" .
                                 $m[1]."\texecute_data = EG(current_execute_data);\n".
                                 $m[1]."\tZEND_VM_LOOP_INTERRUPT_CHECK();\n".
                                 $m[1]."} else {\n" .

ext/opcache/jit/zend_jit_internal.h

@@ -201,6 +201,7 @@ extern const zend_op *zend_jit_halt_op;
 		return; \
 	} while(0)
 # define ZEND_VM_ENTER_BIT 0
+#  define ZEND_VM_RETURN_VAL 0
 #else
 # define EXECUTE_DATA_D                       zend_execute_data* execute_data
 # define EXECUTE_DATA_C                       execute_data
@@ -222,7 +223,13 @@ extern const zend_op *zend_jit_halt_op;
 # define ZEND_OPCODE_TAIL_CALL_EX(handler, arg) do { \
 		return handler(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU_CC arg); \
 	} while(0)
-# define ZEND_VM_ENTER_BIT (1ULL<<(UINTPTR_WIDTH-1))
+# ifdef ZEND_HIGH_HALF_KERNEL
+#  define ZEND_VM_ENTER_BIT (1ULL<<(UINTPTR_WIDTH-1))
+#  define ZEND_VM_RETURN_VAL 0
+# else
+#  define ZEND_VM_ENTER_BIT 1ULL
+#  define ZEND_VM_RETURN_VAL ZEND_VM_ENTER_BIT
+# endif
 #endif
 
 /* VM handlers */

ext/opcache/jit/zend_jit_ir.c

@@ -2401,7 +2401,7 @@ static int zend_jit_trace_halt_stub(zend_jit_ctx *jit)
 		jit_STORE_IP(jit, IR_NULL);
 		ir_RETURN(IR_VOID);
 	} else {
-		ir_RETURN(ir_CONST_ADDR(0)); // ZEND_VM_RETURN
+		ir_RETURN(ir_CONST_ADDR(ZEND_VM_RETURN_VAL)); // ZEND_VM_RETURN
 	}
 	return 1;
 }