sylveos

commit 6a121abe685d378dd68813044283f763bdbc3107
parent df5c42c175e426c3425088bb629739c8c00916db
Author: Sylvia Ivory <git@sivory.net>
Date:   Tue, 10 Feb 2026 19:14:08 -0800

Clobber all registers in interrupts

Diffstat:
M
pi/interrupts.zig
 | 
64
+++++++++++++++++++++++++++++++++-------------------------------

1 file changed, 33 insertions(+), 31 deletions(-)
diff --git a/pi/interrupts.zig b/pi/interrupts.zig
@@ -97,16 +97,9 @@ fn empty(lr: u32) void {
     _ = lr;
 }
 
-// TODO; r1-r6
-fn empty_swi(n: u32, r0: u32) callconv(.c) i32 {
-    _ = n;
-    _ = r0;
-    return -1;
-}
-
 var reset_handler: *const fn (u32) void = empty;
 var undefined_instruction_handler: *const fn (u32) void = empty;
-export var software_interrupt_handler: *const fn (u32, u32) callconv(.c) i32 = empty_swi;
+var software_interrupt_handler: *const fn (u32) void = empty;
 var prefetch_abort_handler: *const fn (u32) void = empty;
 var data_abort_handler: *const fn (u32) void = empty;
 var interrupt_handler: *const fn (u32) void = empty;
@@ -118,43 +111,54 @@ inline fn get_lr() u32 {
     );
 }
 
+inline fn clobber_all() void {
+    asm volatile ("" ::: .{
+            .r0 = true,
+            .r1 = true,
+            .r2 = true,
+            .r3 = true,
+            .r4 = true,
+            .r5 = true,
+            .r6 = true,
+            .r7 = true,
+            .r8 = true,
+            .r9 = true,
+            .r10 = true,
+            .r11 = true,
+            .r12 = true,
+            .r14 = true,
+        });
+}
+
 export fn reset() callconv(.{ .arm_interrupt = .{ .type = .generic } }) void {
-    reset_handler(0);
+    clobber_all();
+    reset_handler(get_lr() - 4);
 }
 export fn undefined_instruction() callconv(.{ .arm_interrupt = .{ .type = .undef } }) void {
+    clobber_all();
     undefined_instruction_handler(get_lr() - 4);
 }
+export fn software_interrupt() callconv(.{ .arm_interrupt = .{ .type = .swi } }) void {
+    clobber_all();
+    software_interrupt_handler(get_lr() - 4);
+}
 export fn prefetch_abort() callconv(.{ .arm_interrupt = .{ .type = .abort } }) void {
+    clobber_all();
     prefetch_abort_handler(get_lr() - 8);
 }
 export fn data_abort() callconv(.{ .arm_interrupt = .{ .type = .abort } }) void {
+    clobber_all();
     data_abort_handler(get_lr() - 4);
 }
 export fn interrupt() callconv(.{ .arm_interrupt = .{ .type = .irq } }) void {
+    clobber_all();
     interrupt_handler(get_lr() - 4);
 }
 export fn fast_interrupt() callconv(.{ .arm_interrupt = .{ .type = .fiq } }) void {
+    clobber_all();
     fast_interrupt_handler(get_lr() - 4);
 }
 
-// TODO; fix
-comptime {
-    asm (
-        \\ .global software_interrupt;
-        \\ .type software_interrupt, %function;
-        \\ software_interrupt:
-        \\   push {r0-r12, lr}
-        \\   sub  lr, lr, #4
-        \\   mov  r1, r0
-        \\   mov  r0, lr
-        \\   bl syscall_handler
-        \\   pop {r0-r12, lr}
-        \\   movs pc, lr
-    );
-}
-extern fn software_interrupt() void;
-export fn syscall_handler() void {}
-
 // https://leiradel.github.io/2019/02/09/Initialization.html
 pub fn setup_exception_vector() void {
     var exception_vector: usize = 0;
@@ -193,6 +197,7 @@ pub fn setup_exception_vector() void {
 const ExceptionVector = enum {
     Reset,
     UndefinedInstruction,
+    SoftwareInterrupt,
     PrefetchAbort,
     DataAbort,
     IRQ,
@@ -203,13 +208,10 @@ pub fn set_exception_handler(vector: ExceptionVector, handler: *const fn (u32) v
     switch (vector) {
         .Reset => reset_handler = handler,
         .UndefinedInstruction => undefined_instruction_handler = handler,
+        .SoftwareInterrupt => software_interrupt_handler = handler,
         .PrefetchAbort => prefetch_abort_handler = handler,
         .DataAbort => data_abort_handler = handler,
         .IRQ => interrupt_handler = handler,
         .FIQ => fast_interrupt_handler = handler,
     }
 }
-
-pub fn set_software_interrupt(handler: *const fn (u32, u32) callconv(.c) i32) void {
-    software_interrupt_handler = handler;
-}