userland: add assembly support

Move arm assembly cheat here, and start some work on x86 cheat as well.

userland/arch/aarch64/common_arch.h

@@ -0,0 +1,64 @@
+#ifndef COMMON_ARCH_H
+#define COMMON_ARCH_H
+
+#define ASSERT_EQ(reg, const) \
+    ldr x11, =const; \
+	cmp reg, x11; \
+	ASSERT(beq); \
+;
+
+#define ASSERT_MEMCMP(s1, s2, n) \
+	MEMCMP(s1, s2, n); \
+	ASSERT_EQ(x0, 0); \
+;
+
+#define ENTRY \
+.text; \
+.global asm_main; \
+asm_main: \
+    sub  sp, sp, 0xA0; \
+    stp  x29, x30, [sp]; \
+    stp  x27, x28, [sp, 0x10]; \
+    stp  x25, x26, [sp, 0x20]; \
+    stp  x23, x24, [sp, 0x30]; \
+    stp  x21, x22, [sp, 0x40]; \
+    stp  x19, x20, [sp, 0x50]; \
+    stp  x6, x7, [sp, 0x60]; \
+    stp  x4, x5, [sp, 0x70]; \
+    stp  x2, x3, [sp, 0x80]; \
+    stp  x0, x1, [sp, 0x90]; \
+asm_main_after_prologue: \
+;
+
+#define EXIT \
+    mov w0, 0; \
+    mov w1, 0; \
+    b pass; \
+fail: \
+    ldr x1, [sp, 0x90]; \
+    str w0, [x1]; \
+    mov w0, 1; \
+pass: \
+    ldp x19, x20, [sp, 0x50]; \
+    ldp x21, x22, [sp, 0x40]; \
+    ldp x23, x24, [sp, 0x30]; \
+    ldp x25, x26, [sp, 0x20]; \
+    ldp x27, x28, [sp, 0x10]; \
+    ldp x29, x30, [sp]; \
+    add sp, sp, 0xA0; \
+    ret; \
+;
+
+#define FAIL \
+    ldr w0, =__LINE__; \
+    b fail; \
+;
+
+#define MEMCMP(s1, s2, n) \
+    adr x0, s1; \
+    adr x1, s2; \
+    ldr x2, =n; \
+    bl memcmp; \
+;
+
+#endif