[interrupt-handlers] addressing @ludfjig 's pr feedback

- consolidating init_idt and load_idt
- added push 0 for exceptions that dont
push their error code to the stack

Signed-off-by: danbugs <[email protected]>

Author: danbugs

src/hyperlight_guest/src/entrypoint.rs

@@ -31,7 +31,6 @@ use crate::{
     OUTB_PTR_WITH_CONTEXT, P_PEB, RUNNING_MODE,
 };
 use crate::gdt::load_gdt;
-use crate::idt::init_idt;
 use crate::idtr::load_idt;
 
 #[inline(never)]
@@ -91,7 +90,6 @@ pub extern "win64" fn entrypoint(peb_address: u64, seed: u64, ops: u64, max_log_
 
             // Set up GDT/IDT
             load_gdt();
-            init_idt();
             load_idt();
 
             // Enable interrupts

src/hyperlight_guest/src/idtr.rs

@@ -1,5 +1,5 @@
 use core::ptr::addr_of;
-use crate::idt::{IdtEntry, IDT};
+use crate::idt::{init_idt, IdtEntry, IDT};
 
 #[repr(C, packed)]
 pub struct Idtr {
@@ -21,6 +21,8 @@ impl Idtr {
 }
 
 pub(crate) unsafe fn load_idt() {
+    init_idt();
+
     let idt_size = 256 * size_of::<IdtEntry>();
     let expected_base = addr_of!(IDT) as *const _ as u64;
 

src/hyperlight_guest/src/interrupt_entry.rs

@@ -127,27 +127,27 @@ macro_rules! generate_exceptions {
             context_restore!(),
             "    mov r14, 495\n",
             "    iretq\n", // iretq is used to return from exception in x86_64
-            generate_excp!(0),
-            generate_excp!(1),
-            generate_excp!(2),
-            generate_excp!(3),
-            generate_excp!(4),
-            generate_excp!(5),
-            generate_excp!(6),
-            generate_excp!(7),
+            generate_excp!(0, pusherrcode),
+            generate_excp!(1, pusherrcode),
+            generate_excp!(2, pusherrcode),
+            generate_excp!(3, pusherrcode),
+            generate_excp!(4, pusherrcode),
+            generate_excp!(5, pusherrcode),
+            generate_excp!(6, pusherrcode),
+            generate_excp!(7, pusherrcode),
             generate_excp!(8),
-            generate_excp!(9),
+            generate_excp!(9, pusherrcode),
             generate_excp!(10),
             generate_excp!(11),
             generate_excp!(12),
             generate_excp!(13),
             generate_excp!(14, pagefault),
-            generate_excp!(15),
-            generate_excp!(16),
+            generate_excp!(15, pusherrcode),
+            generate_excp!(16, pusherrcode),
             generate_excp!(17),
-            generate_excp!(18),
-            generate_excp!(19),
-            generate_excp!(20),
+            generate_excp!(18, pusherrcode),
+            generate_excp!(19, pusherrcode),
+            generate_excp!(20, pusherrcode),
             generate_excp!(30),
         )
     };
@@ -181,6 +181,25 @@ macro_rules! generate_excp {
             "    jmp _do_excp_common\n"
         )
     };
+    ($num:expr, pusherrcode) => {
+        concat!(
+            ".global _do_excp", stringify!($num), "\n",
+            "_do_excp", stringify!($num), ":\n",
+            // Some exceptions push an error code onto the stack.
+            // For the ones that don't, we push a 0 to keep the
+            // stack aligned.
+            "   push 0\n",
+            context_save!(),
+            // In SysV ABI, the second argument is passed in rsi
+            // rsi is the exception number.
+            "    mov rsi, ", stringify!($num), "\n",
+            // In SysV ABI, the third argument is passed in rdx
+            // rdx is only used for pagefault exception and
+            // contains the address that caused the pagefault.
+            "    mov rdx, 0\n",
+            "    jmp _do_excp_common\n"
+        )
+    };
     ($num:expr, pagefault) => {
         concat!(
             ".global _do_excp", stringify!($num), "\n",