kernel/aarch64: Add exception code + frame fixups

- Add handle_exception() as higher level logic to handle the exceptions
- Simplify frame.h
- Call C handler in vector.S
- Clean up stack after creating frame
- Add register dump on exception

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 104 insertions, 51 deletions

diff --git a/sys/include/arch/aarch64/exception.h b/sys/include/arch/aarch64/exception.h
new file mode 100644
index 0000000..9e89c81
--- /dev/null
+++ b/sys/include/arch/aarch64/exception.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MACHINE_EXCEPTION_H_
+#define _MACHINE_EXCEPTION_H_
+
+#include <sys/types.h>
+#include <machine/frame.h>
+
+/* Exception class */
+#define EC_UNKNOWN  0x00    /* Unknown type */
+#define EC_WF       0x01    /* Trapped WF instruction */
+#define EC_MCRMRC   0x03    /* Trapped MCR/MRC */
+#define EC_MCRRC    0x04    /* Trapped MCRR/MRRC */
+#define EC_LDCSTC   0x06    /* Trapped LDC/STC */
+#define EC_SVE      0x07    /* Trapped SVE/SIMD/FP op */
+#define EC_BRE      0x0D    /* Branch target exception */
+#define EC_ILLX     0x0E    /* Illegal execution state */
+#define EC_SVC64    0x15    /* AARCH64 SVC */
+#define EC_PCALIGN  0x22    /* PC alignment fault */
+#define EC_DABORT   0x24    /* Data abort (w/o ELx change) */
+#define EC_EDABORT  0x25    /* Data abort (w/ ELx change) */
+#define EC_SPALIGN  0x26    /* SP alignment fault */
+#define EC_SERR     0x2F    /* System error (what the fuck!) */
+
+void handle_exception(struct trapframe *tf);
+
+#endif  /* !_MACHINE_EXCEPTION_H_ */
diff --git a/sys/include/arch/aarch64/frame.h b/sys/include/arch/aarch64/frame.h
index f14fa01..143f4d0 100644
--- a/sys/include/arch/aarch64/frame.h
+++ b/sys/include/arch/aarch64/frame.h
@@ -31,46 +31,11 @@
 #define _MACHINE_FRAME_H_
 
 #include <sys/types.h>
+#include <sys/cdefs.h>
 
 typedef uint64_t lreg_t;
 typedef uint64_t frament_t;
 
-/* General purpose registers */
-struct gpregs {
-    frament_t trapno;
-    lreg_t x0;
-    lreg_t x1;
-    lreg_t x2;
-    lreg_t x3;
-    lreg_t x4;
-    lreg_t x5;
-    lreg_t x6;
-    lreg_t x7;
-    lreg_t x8;
-    lreg_t x9;
-    lreg_t x10;
-    lreg_t x11;
-    lreg_t x12;
-    lreg_t x13;
-    lreg_t x14;
-    lreg_t x15;
-    lreg_t x16;
-    lreg_t x17;
-    lreg_t x18;
-    lreg_t x19;
-    lreg_t x20;
-    lreg_t x21;
-    lreg_t x22;
-    lreg_t x23;
-    lreg_t x24;
-    lreg_t x25;
-    lreg_t x26;
-    lreg_t x27;
-    lreg_t x28;
-    lreg_t x29;
-    lreg_t x30;
-};
-
 /* Stack regs */
 struct sregs {
     lreg_t sp_el0;
@@ -85,14 +50,41 @@ struct pstat {
     lreg_t spsr_el3;
 };
 
-struct trapframe {
-    struct gpregs gp;
-    struct sregs stack;
-    struct pstat status;
-    lreg_t elr_el1;
-    lreg_t elr_el2;
-    lreg_t elr_el3;
-    lreg_t pc;
+struct __aligned(16) trapframe {
+    lreg_t x30;
+    lreg_t x29;
+    lreg_t x28;
+    lreg_t x27;
+    lreg_t x26;
+    lreg_t x25;
+    lreg_t x24;
+    lreg_t x23;
+    lreg_t x22;
+    lreg_t x21;
+    lreg_t x20;
+    lreg_t x19;
+    lreg_t x18;
+    lreg_t x17;
+    lreg_t x16;
+    lreg_t x15;
+    lreg_t x14;
+    lreg_t x13;
+    lreg_t x12;
+    lreg_t x11;
+    lreg_t x10;
+    lreg_t x9;
+    lreg_t x8;
+    lreg_t x7;
+    lreg_t x6;
+    lreg_t x5;
+    lreg_t x4;
+    lreg_t x3;
+    lreg_t x2;
+    lreg_t x1;
+    lreg_t x0;
+    lreg_t elr;
+    lreg_t esr;
+    frament_t trapno;
 };
 
 #define TF_IP(TFP) ((TFP)->pc)
diff --git a/sys/include/arch/aarch64/frameasm.h b/sys/include/arch/aarch64/frameasm.h
index 5664ff5..ca7f81a 100644
--- a/sys/include/arch/aarch64/frameasm.h
+++ b/sys/include/arch/aarch64/frameasm.h
@@ -31,13 +31,14 @@
 #define _MACHINE_FRAMEASM_H_
 
 /* XXX: Must be 16-byte aligned!!! */
-#define XFRAME_STACK_SIZE (34 * 8)
+#define XFRAME_STACK_SIZE (38 * 8)
 
 /* Trap numbers */
-#define TRAPNO_XSYNC  #0     /* Synchronous */
-#define TRAPNO_XIRQ   #1     /* IRQ */
-#define TRAPNO_XFIQ   #2     /* FIQ */
-#define TRAPNO_XSERR  #3     /* System error */
+#define TRAPNO_UNKNOWN #0
+#define TRAPNO_XSYNC   #1     /* Synchronous */
+#define TRAPNO_XIRQ    #2     /* IRQ */
+#define TRAPNO_XFIQ    #3     /* FIQ */
+#define TRAPNO_XSERR   #4     /* System error */
 
 #define PUSH_XFRAME(TRAPNO)          \
     sub sp, sp, #XFRAME_STACK_SIZE ; \
@@ -57,11 +58,16 @@
     stp x4, x3, [sp, #(26 * 8)]    ; \
     stp x2, x1, [sp, #(28 * 8)]    ; \
     str x0, [sp, #(30 * 8)]        ; \
+                                   ; \
+    mrs x0, elr_el1                ; \
+    str x0, [sp, #(31 * 8)]        ; \
+    mrs x0, esr_el1                ; \
+    str x0, [sp, #(32 * 8)]        ; \
     mov x0, TRAPNO                 ; \
-    str x0, [sp, #(31 * 8)]
+    str x0, [sp, #(33 * 8)]        ; \
+    mov x0, sp
 
 #define POP_XFRAME()                  \
-    add sp, sp, #8                  ; \
     ldr x0, [sp, #(30 * 8)]         ; \
     ldp x2, x1, [sp, #(28 * 8)]     ; \
     ldp x4, x3, [sp, #(26 * 8)]     ; \
@@ -78,5 +84,6 @@
     ldp x26, x25, [sp, #(4 * 8)]    ; \
     ldp x28, x27, [sp, #(2 * 8)]    ; \
     ldp x30, x29, [sp, #(0 * 8)]    ; \
+    add sp, sp, #XFRAME_STACK_SIZE
 
 #endif  /* !_MACHINE_FRAMEASM_H_ */