496 lines
16 KiB
Zig
496 lines
16 KiB
Zig
const std = @import("std");
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const log = std.log.scoped(.x86_syscalls);
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const builtin = @import("builtin");
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const is_test = builtin.is_test;
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const build_options = @import("build_options");
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const arch = if (is_test) @import("../../../../test/mock/kernel/arch_mock.zig") else @import("arch.zig");
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const testing = std.testing;
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const expect = std.testing.expect;
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const isr = @import("isr.zig");
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const panic = @import("../../panic.zig").panic;
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const syscalls = @import("../../syscalls.zig");
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/// The isr number associated with syscalls
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pub const INTERRUPT: u16 = 0x80;
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/// The maximum number of syscall handlers that can be registered
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pub const NUM_HANDLERS: u16 = 256;
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/// A syscall handler
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pub const Handler = fn (arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize;
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/// Errors that syscall utility functions can throw
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pub const Error = error{
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SyscallExists,
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InvalidSyscall,
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};
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comptime {
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std.debug.assert(@typeInfo(syscalls.Syscall).Enum.fields.len <= NUM_HANDLERS);
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}
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/// The array of registered syscalls
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var handlers: [NUM_HANDLERS]?Handler = [_]?Handler{null} ** NUM_HANDLERS;
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///
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/// Returns true if the syscall is valid, else false.
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/// A syscall is valid if it's less than NUM_HANDLERS.
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///
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/// Arguments:
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/// IN syscall: u32 - The syscall to check
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///
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/// Return: bool
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/// Whether the syscall number is valid.
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///
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pub fn isValidSyscall(syscall: u32) bool {
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return syscall < NUM_HANDLERS;
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}
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///
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/// Handle a syscall. Gets the syscall number from eax within the context and calls the registered
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/// handler. If an error occurs ebx will be set to its error code, or 0 otherwise.
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/// The syscall result will be stored in eax. If there isn't a registered handler or the syscall is
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/// invalid (>= NUM_HANDLERS) then a warning is logged.
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///
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/// Arguments:
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/// IN ctx: *arch.CpuState - The cpu context when the syscall was triggered. The
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/// syscall number is stored in eax.
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///
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/// Return: usize
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/// The new stack pointer value
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///
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fn handle(ctx: *arch.CpuState) usize {
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// The syscall number is put in eax
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const syscall = ctx.eax;
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if (isValidSyscall(syscall)) {
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if (handlers[syscall]) |handler| {
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const result = handler(syscallArg(ctx, 0), syscallArg(ctx, 1), syscallArg(ctx, 2), syscallArg(ctx, 3), syscallArg(ctx, 4));
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if (result) |res| {
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ctx.eax = res;
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ctx.ebx = 0;
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} else |e| {
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ctx.ebx = syscalls.toErrorCode(e);
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}
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} else {
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log.warn("Syscall {} triggered but not registered\n", .{syscall});
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}
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} else {
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log.warn("Syscall {} is invalid\n", .{syscall});
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}
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return @ptrToInt(ctx);
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}
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///
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/// Register a syscall so it can be called by triggering interrupt 128 and putting its number in eax.
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///
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/// Arguments:
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/// IN syscall: usize - The syscall to register the handler with.
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/// IN handler: Handler - The handler to register the syscall with.
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///
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/// Errors: Error
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/// Error.SyscallExists - If the syscall has already been registered.
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/// Error.InvalidSyscall - If the syscall is invalid. See isValidSyscall.
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///
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pub fn registerSyscall(syscall: usize, handler: Handler) Error!void {
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if (!isValidSyscall(syscall))
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return Error.InvalidSyscall;
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if (handlers[syscall]) |_|
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return Error.SyscallExists;
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handlers[syscall] = handler;
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}
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///
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/// Trigger a syscall with no arguments. Returns the value put in eax by the syscall or the error returned in ebx.
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///
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/// Arguments:
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/// IN syscall: usize - The syscall to trigger, put in eax.
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///
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/// Return: usize
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/// The return value from the syscall.
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///
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/// Error: syscalls.Error
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/// This function will return the error that the syscall handler returns. See the documentation for the syscall for details.
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///
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inline fn syscall0(syscall: usize) syscalls.Error!usize {
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const res = asm volatile (
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\\int $0x80
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: [ret] "={eax}" (-> usize),
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: [syscall] "{eax}" (syscall),
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: "ebx"
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);
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const err = asm (""
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: [ret] "={ebx}" (-> usize),
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);
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if (err != 0) {
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return syscalls.fromErrorCode(err);
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}
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return res;
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}
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///
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/// Trigger a syscall with one argument. Returns the value put in eax by the syscall or the error returned in ebx.
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///
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/// Arguments:
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/// IN syscall: usize - The syscall to trigger, put in eax.
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/// IN arg: usize - The argument to pass. Put in ebx.
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///
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/// Return: usize
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/// The return value from the syscall.
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///
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/// Error: syscalls.Error
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/// This function will return the error that the syscall handler returns. See the documentation for the syscall for details.
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///
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inline fn syscall1(syscall: usize, arg: usize) syscalls.Error!usize {
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const res = asm volatile (
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\\int $0x80
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: [ret] "={eax}" (-> usize),
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: [syscall] "{eax}" (syscall),
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[arg1] "{ebx}" (arg),
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);
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const err = asm (""
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: [ret] "={ebx}" (-> usize),
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);
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if (err != 0) {
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return syscalls.fromErrorCode(err);
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}
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return res;
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}
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///
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/// Trigger a syscall with two arguments. Returns the value put in eax by the syscall or the error returned in ebx.
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///
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/// Arguments:
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/// IN syscall: usize - The syscall to trigger, put in eax.
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/// IN arg1: usize - The first argument to pass. Put in ebx.
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/// IN arg2: usize - The second argument to pass. Put in ecx.
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///
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/// Return: usize
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/// The return value from the syscall.
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///
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/// Error: syscalls.Error
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/// This function will return the error that the syscall handler returns. See the documentation for the syscall for details.
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///
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inline fn syscall2(syscall: usize, arg1: usize, arg2: usize) syscalls.Error!usize {
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const res = asm volatile (
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\\int $0x80
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: [ret] "={eax}" (-> usize),
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: [syscall] "{eax}" (syscall),
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[arg1] "{ebx}" (arg1),
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[arg2] "{ecx}" (arg2),
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);
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const err = asm (""
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: [ret] "={ebx}" (-> usize),
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);
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if (err != 0) {
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return syscalls.fromErrorCode(err);
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}
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return res;
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}
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///
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/// Trigger a syscall with three arguments. Returns the value put in eax by the syscall or the error returned in ebx.
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///
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/// Arguments:
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/// IN syscall: usize - The syscall to trigger, put in eax.
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/// IN arg1: usize - The first argument to pass. Put in ebx.
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/// IN arg2: usize - The second argument to pass. Put in ecx.
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/// IN arg3: usize - The third argument to pass. Put in edx.
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///
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/// Return: usize
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/// The return value from the syscall.
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///
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/// Error: syscalls.Error
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/// This function will return the error that the syscall handler returns. See the documentation for the syscall for details.
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///
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inline fn syscall3(syscall: usize, arg1: usize, arg2: usize, arg3: usize) syscalls.Error!usize {
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const res = asm volatile (
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\\int $0x80
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: [ret] "={eax}" (-> usize),
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: [syscall] "{eax}" (syscall),
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[arg1] "{ebx}" (arg1),
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[arg2] "{ecx}" (arg2),
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[arg3] "{edx}" (arg3),
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);
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const err = asm (""
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: [ret] "={ebx}" (-> usize),
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);
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if (err != 0) {
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return syscalls.fromErrorCode(err);
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}
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return res;
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}
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///
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/// Trigger a syscall with four arguments. Returns the value put in eax by the syscall or the error returned in ebx.
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///
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/// Arguments:
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/// IN syscall: usize - The syscall to trigger, put in eax.
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/// IN arg1: usize - The first argument to pass. Put in ebx.
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/// IN arg2: usize - The second argument to pass. Put in ecx.
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/// IN arg3: usize - The third argument to pass. Put in edx.
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/// IN arg4: usize - The fourth argument to pass. Put in esi.
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///
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/// Return: usize
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/// The return value from the syscall.
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///
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/// Error: syscalls.Error
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/// This function will return the error that the syscall handler returns. See the documentation for the syscall for details.
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///
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inline fn syscall4(syscall: usize, arg1: usize, arg2: usize, arg3: usize, arg4: usize) syscalls.Error!usize {
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const res = asm volatile (
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\\int $0x80
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: [ret] "={eax}" (-> usize),
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: [syscall] "{eax}" (syscall),
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[arg1] "{ebx}" (arg1),
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[arg2] "{ecx}" (arg2),
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[arg3] "{edx}" (arg3),
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[arg4] "{esi}" (arg4),
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);
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const err = asm (""
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: [ret] "={ebx}" (-> usize),
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);
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if (err != 0) {
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return syscalls.fromErrorCode(err);
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}
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return res;
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}
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///
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/// Trigger a syscall with five arguments. Returns the value put in eax by the syscall or the error returned in ebx.
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///
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/// Arguments:
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/// IN syscall: usize - The syscall to trigger, put in eax.
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/// IN arg1: usize - The first argument to pass. Put in ebx.
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/// IN arg2: usize - The second argument to pass. Put in ecx.
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/// IN arg3: usize - The third argument to pass. Put in edx.
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/// IN arg4: usize - The fourth argument to pass. Put in esi.
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/// IN arg5: usize - The fifth argument to pass. Put in edi.
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///
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/// Return: usize
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/// The return value from the syscall.
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///
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/// Error: syscalls.Error
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/// This function will return the error that the syscall handler returns. See the documentation for the syscall for details.
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///
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inline fn syscall5(syscall: usize, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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const res = asm volatile (
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\\int $0x80
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: [ret] "={eax}" (-> usize),
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: [syscall] "{eax}" (syscall),
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[arg1] "{ebx}" (arg1),
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[arg2] "{ecx}" (arg2),
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[arg3] "{edx}" (arg3),
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[arg4] "{esi}" (arg4),
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[arg5] "{edi}" (arg5),
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);
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const err = asm (""
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: [ret] "={ebx}" (-> usize),
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);
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if (err != 0) {
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return syscalls.fromErrorCode(err);
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}
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return res;
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}
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///
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/// Gets the syscall argument according to the given index. 0 => ebx, 1 => ecx, 2 => edx,
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/// 3 => esi and 4 => edi.
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///
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/// Arguments:
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/// IN ctx: *arch.CpuState - The interrupt context from which to get the argument
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/// IN arg_idx: comptime u32 - The argument index to get. Between 0 and 4.
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///
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/// Return: usize
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/// The syscall argument from the given index.
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///
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inline fn syscallArg(ctx: *arch.CpuState, comptime arg_idx: u32) usize {
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return switch (arg_idx) {
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0 => ctx.ebx,
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1 => ctx.ecx,
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2 => ctx.edx,
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3 => ctx.esi,
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4 => ctx.edi,
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else => @compileError("Arg index must be between 0 and 4"),
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};
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}
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///
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/// Construct a handler for a syscall.
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///
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/// Arguments:
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/// IN comptime syscall: Syscall - The syscall to construct the handler for.
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///
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/// Return: Handler
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/// The handler function constructed.
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///
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fn makeHandler(comptime syscall: syscalls.Syscall) Handler {
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return struct {
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fn func(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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return syscalls.handle(syscall, arg1, arg2, arg3, arg4, arg5);
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}
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}.func;
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}
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///
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/// Initialise syscalls. Registers the isr associated with INTERRUPT and sets up handlers for each syscall.
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///
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pub fn init() void {
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log.info("Init\n", .{});
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defer log.info("Done\n", .{});
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isr.registerIsr(INTERRUPT, handle) catch |e| {
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panic(@errorReturnTrace(), "Failed to register syscall ISR: {}\n", .{e});
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};
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inline for (std.meta.fields(syscalls.Syscall)) |field| {
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const syscall = @intToEnum(syscalls.Syscall, field.value);
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registerSyscall(field.value, makeHandler(syscall)) catch |e| {
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panic(@errorReturnTrace(), "Failed to register syscall for '" ++ field.name ++ "': {}\n", .{e});
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};
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}
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switch (build_options.test_mode) {
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.Initialisation => runtimeTests(),
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else => {},
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}
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}
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/// Tests
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var test_int: u32 = 0;
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fn testHandler0(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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// Suppress unused variable warnings
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_ = arg1;
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_ = arg2;
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_ = arg3;
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_ = arg4;
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_ = arg5;
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test_int += 1;
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return 0;
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}
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fn testHandler1(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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// Suppress unused variable warnings
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_ = arg2;
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_ = arg3;
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_ = arg4;
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_ = arg5;
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test_int += arg1;
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return 1;
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}
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fn testHandler2(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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// Suppress unused variable warnings
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_ = arg3;
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_ = arg4;
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_ = arg5;
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test_int += arg1 + arg2;
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return 2;
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}
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fn testHandler3(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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// Suppress unused variable warnings
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_ = arg4;
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_ = arg5;
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test_int += arg1 + arg2 + arg3;
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return 3;
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}
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fn testHandler4(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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// Suppress unused variable warnings
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_ = arg5;
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test_int += arg1 + arg2 + arg3 + arg4;
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return 4;
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}
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fn testHandler5(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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test_int += arg1 + arg2 + arg3 + arg4 + arg5;
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return 5;
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}
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fn testHandler6(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) syscalls.Error!usize {
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// Suppress unused variable warnings
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_ = arg1;
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_ = arg2;
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_ = arg3;
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_ = arg4;
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_ = arg5;
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return syscalls.Error.OutOfMemory;
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}
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test "registerSyscall returns SyscallExists" {
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try registerSyscall(122, testHandler0);
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try std.testing.expectError(Error.SyscallExists, registerSyscall(122, testHandler0));
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}
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fn runtimeTests() void {
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registerSyscall(121, testHandler6) catch |e| panic(@errorReturnTrace(), "FAILURE registering handler 6: {}\n", .{e});
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registerSyscall(122, testHandler0) catch |e| panic(@errorReturnTrace(), "FAILURE registering handler 0: {}\n", .{e});
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registerSyscall(123, testHandler1) catch |e| panic(@errorReturnTrace(), "FAILURE registering handler 1: {}\n", .{e});
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registerSyscall(124, testHandler2) catch |e| panic(@errorReturnTrace(), "FAILURE registering handler 2: {}\n", .{e});
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registerSyscall(125, testHandler3) catch |e| panic(@errorReturnTrace(), "FAILURE registering handler 3: {}\n", .{e});
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registerSyscall(126, testHandler4) catch |e| panic(@errorReturnTrace(), "FAILURE registering handler 4: {}\n", .{e});
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registerSyscall(127, testHandler5) catch |e| panic(@errorReturnTrace(), "FAILURE registering handler 5: {}\n", .{e});
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if (test_int != 0) {
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panic(@errorReturnTrace(), "FAILURE initial test_int not 0: {}\n", .{test_int});
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}
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if (syscall0(122)) |res| {
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if (res != 0 or test_int != 1) {
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panic(@errorReturnTrace(), "FAILURE syscall0\n", .{});
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}
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} else |e| {
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panic(@errorReturnTrace(), "FAILURE syscall0 errored: {}\n", .{e});
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}
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if (syscall1(123, 2)) |res| {
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if (res != 1 or test_int != 3) {
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panic(@errorReturnTrace(), "FAILURE syscall1\n", .{});
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}
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} else |e| {
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panic(@errorReturnTrace(), "FAILURE syscall1 errored: {}\n", .{e});
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}
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if (syscall2(124, 2, 3)) |res| {
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if (res != 2 or test_int != 8) {
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panic(@errorReturnTrace(), "FAILURE syscall2\n", .{});
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}
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} else |e| {
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panic(@errorReturnTrace(), "FAILURE syscall2 errored: {}\n", .{e});
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}
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if (syscall3(125, 2, 3, 4)) |res| {
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if (res != 3 or test_int != 17) {
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panic(@errorReturnTrace(), "FAILURE syscall3\n", .{});
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}
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} else |e| {
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panic(@errorReturnTrace(), "FAILURE syscall3 errored: {}\n", .{e});
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}
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if (syscall4(126, 2, 3, 4, 5)) |res| {
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if (res != 4 or test_int != 31) {
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panic(@errorReturnTrace(), "FAILURE syscall4\n", .{});
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}
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} else |e| {
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panic(@errorReturnTrace(), "FAILURE syscall4 errored: {}\n", .{e});
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}
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if (syscall5(127, 2, 3, 4, 5, 6)) |res| {
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if (res != 5 or test_int != 51) {
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panic(@errorReturnTrace(), "FAILURE syscall5\n", .{});
|
|
}
|
|
} else |e| {
|
|
panic(@errorReturnTrace(), "FAILURE syscall5 errored: {}\n", .{e});
|
|
}
|
|
|
|
if (syscall0(121)) {
|
|
panic(@errorReturnTrace(), "FAILURE syscall6\n", .{});
|
|
} else |e| {
|
|
if (e != syscalls.Error.OutOfMemory) {
|
|
panic(@errorReturnTrace(), "FAILURE syscall6 returned the wrong error: {}\n", .{e});
|
|
}
|
|
}
|
|
|
|
log.info("Tested all args\n", .{});
|
|
}
|