userland: add ported to all archs

README.adoc

@@ -11362,10 +11362,12 @@ This verifies that the venerable `add` instruction and our setup are working.
 Then, modify that program to make the assertion fail:
 
 ....
-TODO
+ASSERT_EQ(%rax, $4)
 ....
 
-and then watch the assertion fail:
+because 1 + 2 tends to equal 3 instead of 4.
+
+And then watch the assertion fail:
 
 ....
 ./build-userland
@@ -11375,10 +11377,10 @@ and then watch the assertion fail:
 with error message:
 
 ....
-TODO
+error 1 at line 8
 ....
 
-Notice how we give the actual assembly line number where the failing assert was!
+and notice how we give the actual assembly line number where the failing assert was!
 
 Other setup sanity checks that you might want to look into include:
 

userland/arch/x86_64/add.S

@@ -0,0 +1,9 @@
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#userland-assembly */
+
+#include "common.h"
+
+ENTRY
+    mov $1, %rax
+    add $2, %rax
+    ASSERT_EQ(%rax, $3)
+EXIT

userland/arch/x86_64/common_arch.h

@@ -9,9 +9,9 @@
     mov reg, %rax; \
     mov const, %rbx; \
     cmp %rax, %rbx; \
-    ASSERT(je); \
     pop %rbx; \
     pop %rax; \
+    ASSERT(je); \
 ;
 
 # TODO