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minor refactoring

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This commit is contained in:
Pascal Zittlau
2025-12-15 11:31:12 +01:00
parent f4064aff89
commit d0c227faa8
2 changed files with 69 additions and 41 deletions
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11
src/Patcher.zig
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@@ -39,9 +39,12 @@ const prefixes = [_]u8{
0x36,
};
var syscall_flicken_bytes = [13]u8{
0x49, 0xBB, // mov r11
0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, // 8byte immediate
/// As of the SysV ABI: 'The kernel destroys registers %rcx and %r11."
/// So we put the address of the function to call into %r11.
// TODO: Don't we need to save the red zone here, because we push the return address onto the stack
// with the `call r11` instruction?
var syscall_flicken_bytes = [_]u8{
0x49, 0xBB, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, // mov r11 <imm>
0x41, 0xff, 0xd3, // call r11
};
@@ -65,7 +68,7 @@ pub fn init() !void {
page_size / @sizeOf(Flicken),
);
flicken_templates.putAssumeCapacity("nop", .{ .name = "nop", .bytes = &.{} });
mem.writeInt(u64, syscall_flicken_bytes[2..][0..8], @intFromPtr(&syscalls.syscall_entry), .little);
mem.writeInt(u64, syscall_flicken_bytes[4..][0..8], @intFromPtr(&syscalls.syscall_entry), .little);
flicken_templates.putAssumeCapacity("syscall", .{ .name = "syscall", .bytes = &syscall_flicken_bytes });
{