arm: signed LDR example with LDRSW

2026-01-23 02:05:57 +01:00 · 2019-08-25 00:00:00 +00:00
parent 0acff266e2
commit 6dfc95d73a
2 changed files with 34 additions and 0 deletions
--- a/userland/arch/aarch64/ldrsw.S
+++ b/userland/arch/aarch64/ldrsw.S
@@ -0,0 +1,30 @@
+/* https://cirosantilli.com/linux-kernel-module-cheat#arm-ldrh-and-ldrb-instructions */
+
+#include <lkmc.h>
+
+LKMC_PROLOGUE
+    ldr x19, =zero_extend
+
+    mov x0, 0x0
+    ldr w0, [x19]
+    LKMC_ASSERT_EQ(x0, =0x0000000012345678)
+
+    mov x0, 0x0
+    ldrsw x0, [x19]
+    LKMC_ASSERT_EQ(x0, =0x0000000012345678)
+
+    ldr x19, =one_extend
+
+    mov x0, 0x0
+    ldr w0, [x19]
+    LKMC_ASSERT_EQ(x0, =0x0000000082345678)
+
+    mov x0, 0x0
+    ldrsw x0, [x19]
+    LKMC_ASSERT_EQ(x0, =0xFFFFFFFF82345678)
+
+LKMC_EPILOGUE
+zero_extend:
+    .word 0x12345678
+one_extend:
+    .word 0x82345678