arm: thumb understanding++

userland/arch/aarch64/dump_regs.c

@@ -0,0 +1,21 @@
+/* Dump non-EL0 readable registers. We need a separate program from EL0
+ * because we cannot determine the current EL from EL0, since CurrentEL
+ * cannot be read from it.
+ */
+
+#include <stdio.h>
+#include <inttypes.h>
+
+int main(void) {
+    uint32_t sctlr_el1;
+    __asm__ ("mrs %0, sctlr_el1" : "=r" (sctlr_el1) : :);
+    printf("SCTLR_EL1 0x%" PRIX32 "\n", sctlr_el1);
+    printf("SCTLR_EL1.A 0x%" PRIX32 "\n", (sctlr_el1 >> 1) & 1);
+
+    uint64_t CurrentEL;
+    __asm__ ("mrs %0, CurrentEL;" : "=r" (CurrentEL) : :);
+    printf("CurrentEL 0x%" PRIX64 "\n", CurrentEL);
+    /* https://github.com/cirosantilli/linux-kernel-module-cheat#arm-exception-levels */
+    printf("CurrentEL.EL 0x%" PRIX64 "\n", CurrentEL >> 2);
+    return 0;
+}