From 3fb667d62ee5e69a079cd5dce66f3c0f84ba11f4 Mon Sep 17 00:00:00 2001
From: Mathieu Maret <mathieu.maret@gmail.com>
Date: Tue, 26 Oct 2021 20:22:10 +0200
Subject: [PATCH] Core exception handling w or wo err code

---
 arch/x86/exception_wrappers.S | 160 +++++++++++++++++++++++++---------
 debug.gdb                     |   2 +
 2 files changed, 119 insertions(+), 43 deletions(-)

diff --git a/arch/x86/exception_wrappers.S b/arch/x86/exception_wrappers.S
index 34dd39e..4ba8b55 100644
--- a/arch/x86/exception_wrappers.S
+++ b/arch/x86/exception_wrappers.S
@@ -22,36 +22,108 @@
     .type exception_wrapper_\id,@function
         /* INTERRUPT FRAME START */
         /* ALREADY PUSHED TO US BY THE PROCESSOR UPON ENTRY TO THIS INTERRUPT */
-        /* uint32_t ip */
-        /* uint32_t cs; */
         /* uint32_t flags */
+        /* uint32_t cs; */
+        /* uint32_t ip */
         /* Pushes the other reg to save same and look like a struct cpu_state*/
         /* Fake error code */
-		pushl $0
+        pushl $0
 
-		/* Backup the actual context */
-		pushl %ebp
-		movl %esp, %ebp
+        /* Backup the actual context */
+        pushl %ebp
+        movl %esp, %ebp
 
-		pushl %eax
-		pushl %ecx
-		pushl %edx
-		pushl %ebx
-		pushl %esi
-		pushl %edi
-		subl  $2,%esp
-		pushw %ss
-		pushw %ds
-		pushw %es
-		pushw %fs
-		pushw %gs
+        pushl %eax
+        pushl %ecx
+        pushl %edx
+        pushl %ebx
+        pushl %esi
+        pushl %edi
+        subl  $2,%esp
+        pushw %ss
+        pushw %ds
+        pushw %es
+        pushw %fs
+        pushw %gs
 
-		/* Set correct kernel segment descriptors' value */
-		movw $BUILD_SEGMENT_REG_VALUE(0, 0, SEG_KDATA), %di
-		pushw %di ; popw %ds
-		pushw %di ; popw %es
-		pushw %di ; popw %fs
-		pushw %di ; popw %gs
+        /* Set correct kernel segment descriptors' value */
+        movw $BUILD_SEGMENT_REG_VALUE(0, 0, SEG_KDATA), %di
+        pushw %di ; popw %ds
+        pushw %di ; popw %es
+        pushw %di ; popw %fs
+        pushw %di ; popw %gs
+
+        push %esp
+        pushl $\id
+        call exception_handler_wrap
+        addl $8, %esp
+
+        /* Reconfigure the MMU if needed */
+        pushl %esp /* cpu_ctxt */
+        call thread_prepare_exception_switch_back
+        addl  $4, %esp /* Unallocate the stack */
+
+        /* Prepare kernel TSS in case we are switching to a
+           user thread: we make sure that we will come back
+           into the kernel at a correct stack location */
+        pushl %esp /* Pass the location of the context we are
+                      restoring to the function */
+        call cpu_context_update_kernel_tss
+        addl $4, %esp
+
+        /* Restore the context */
+        popw  %gs
+        popw  %fs
+        popw  %es
+        popw  %ds
+        popw  %ss
+        addl  $2,%esp
+        popl %edi
+        popl %esi
+        popl %ebx
+        popl %edx
+        popl %ecx
+        popl %eax
+        popl %ebp
+        /* Remove fake error code */
+        addl  $4, %esp
+
+        iret
+.endm
+
+.macro exception_mac_with_errcode id
+    exception_wrapper_\id:
+    .type exception_wrapper_\id,@function
+        /* INTERRUPT FRAME START */
+        /* ALREADY PUSHED TO US BY THE PROCESSOR UPON ENTRY TO THIS INTERRUPT */
+        /* uint32_t flags */
+        /* uint32_t cs; */
+        /* uint32_t ip */
+        /* Pushes the other reg to save same and look like a struct cpu_state*/
+
+        /* Backup the actual context */
+        pushl %ebp
+        movl %esp, %ebp
+
+        pushl %eax
+        pushl %ecx
+        pushl %edx
+        pushl %ebx
+        pushl %esi
+        pushl %edi
+        subl  $2,%esp
+        pushw %ss
+        pushw %ds
+        pushw %es
+        pushw %fs
+        pushw %gs
+
+        /* Set correct kernel segment descriptors' value */
+        movw $BUILD_SEGMENT_REG_VALUE(0, 0, SEG_KDATA), %di
+        pushw %di ; popw %ds
+        pushw %di ; popw %es
+        pushw %di ; popw %fs
+        pushw %di ; popw %gs
 
         push %esp
         pushl $\id
@@ -72,30 +144,32 @@
         addl $4, %esp
 
 		/* Restore the context */
-		popw  %gs
-		popw  %fs
-		popw  %es
-	        popw  %ds
-		popw  %ss
-		addl  $2,%esp
-		popl %edi
-		popl %esi
-		popl %ebx
-		popl %edx
-		popl %ecx
-		popl %eax
-		popl %ebp
-		/* Remove fake error code */
-		addl  $4, %esp
+        popw  %gs
+        popw  %fs
+        popw  %es
+        popw  %ds
+        popw  %ss
+        addl  $2,%esp
+        popl %edi
+        popl %esi
+        popl %ebx
+        popl %edx
+        popl %ecx
+        popl %eax
+        popl %ebp
+        /* Remove fake error code */
+        addl  $4, %esp
 
         iret
 .endm
 
+/*List of exception w or w/o err codehttps://wiki.osdev.org/Exceptions*/
+.irp exception_id, 8, 10, 11, 12, 13, 14, 17, 30
+    exception_mac_with_errcode exception_id
+.endr
 
-.set i, 0
-.rept 0x20
-    exception_mac %i
-    .set i, i+1
+.irp exception_id, 0, 1, 2, 3, 4, 5, 6, 7, 9, 15, 16, 18, 19, 20 21, 22, 23, 24, 25, 26, 27, 28, 29, 31
+    exception_mac exception_id
 .endr
 
 .macro ref_exception_wrapper id
diff --git a/debug.gdb b/debug.gdb
index a78e6cd..6828808 100644
--- a/debug.gdb
+++ b/debug.gdb
@@ -1,3 +1,5 @@
 add-symbol-file kernel.sym
 source custom_gdb_extension.py
+#For ASM sources
+directory arch/x86/:core
 target remote | qemu-system-i386 -S -gdb stdio -kernel kernel -m 16M