Merge pull request #319 from ZystemOS/f/syscall-ctx

Pass cpu state to syscall handler

src/kernel/arch/x86/arch.zig

@@ -87,6 +87,31 @@ pub const CpuState = packed struct {
     eflags: u32,
     user_esp: u32,
     user_ss: u32,
+
+    pub fn empty() CpuState {
+        return .{
+            .cr3 = undefined,
+            .gs = undefined,
+            .fs = undefined,
+            .es = undefined,
+            .ds = undefined,
+            .edi = undefined,
+            .esi = undefined,
+            .ebp = undefined,
+            .esp = undefined,
+            .ebx = undefined,
+            .edx = undefined,
+            .ecx = undefined,
+            .eax = undefined,
+            .int_num = undefined,
+            .error_code = undefined,
+            .eip = undefined,
+            .cs = undefined,
+            .eflags = undefined,
+            .user_esp = undefined,
+            .user_ss = undefined,
+        };
+    }
 };
 
 /// x86's boot payload is the multiboot info passed by grub

src/kernel/arch/x86/syscalls.zig

@@ -17,7 +17,7 @@ pub const INTERRUPT: u16 = 0x80;
 pub const NUM_HANDLERS: u16 = 256;
 
 /// A syscall handler
-pub const Handler = fn (arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize;
+pub const Handler = fn (ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize;
 
 /// Errors that syscall utility functions can throw
 pub const Error = error{
@@ -64,7 +64,7 @@ fn handle(ctx: *arch.CpuState) usize {
     const syscall = ctx.eax;
     if (isValidSyscall(syscall)) {
         if (handlers[syscall]) |handler| {
-            const result = handler(syscallArg(ctx, 0), syscallArg(ctx, 1), syscallArg(ctx, 2), syscallArg(ctx, 3), syscallArg(ctx, 4));
+            const result = handler(ctx, syscallArg(ctx, 0), syscallArg(ctx, 1), syscallArg(ctx, 2), syscallArg(ctx, 3), syscallArg(ctx, 4));
             if (result) |res| {
                 ctx.eax = res;
                 ctx.ebx = 0;
@@ -297,13 +297,13 @@ inline fn syscall5(syscall: usize, arg1: usize, arg2: usize, arg3: usize, arg4:
 /// 3 => esi and 4 => edi.
 ///
 /// Arguments:
-///     IN ctx: *arch.CpuState - The interrupt context from which to get the argument
+///     IN ctx: *const arch.CpuState - The interrupt context from which to get the argument
 ///     IN arg_idx: comptime u32 - The argument index to get. Between 0 and 4.
 ///
 /// Return: usize
 ///     The syscall argument from the given index.
 ///
-inline fn syscallArg(ctx: *arch.CpuState, comptime arg_idx: u32) usize {
+inline fn syscallArg(ctx: *const arch.CpuState, comptime arg_idx: u32) usize {
     return switch (arg_idx) {
         0 => ctx.ebx,
         1 => ctx.ecx,
@@ -325,8 +325,8 @@ inline fn syscallArg(ctx: *arch.CpuState, comptime arg_idx: u32) usize {
 ///
 fn makeHandler(comptime syscall: syscalls.Syscall) Handler {
     return struct {
-        fn func(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+        fn func(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
-            return syscalls.handle(syscall, arg1, arg2, arg3, arg4, arg5);
+            return syscalls.handle(syscall, ctx, arg1, arg2, arg3, arg4, arg5);
         }
     }.func;
 }
@@ -360,8 +360,9 @@ pub fn init() void {
 /// Tests
 var test_int: u32 = 0;
 
-fn testHandler0(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+fn testHandler0(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
     // Suppress unused variable warnings
+    _ = ctx;
     _ = arg1;
     _ = arg2;
     _ = arg3;
@@ -371,8 +372,9 @@ fn testHandler0(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize)
     return 0;
 }
 
-fn testHandler1(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+fn testHandler1(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
     // Suppress unused variable warnings
+    _ = ctx;
     _ = arg2;
     _ = arg3;
     _ = arg4;
@@ -381,8 +383,9 @@ fn testHandler1(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize)
     return 1;
 }
 
-fn testHandler2(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+fn testHandler2(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
     // Suppress unused variable warnings
+    _ = ctx;
     _ = arg3;
     _ = arg4;
     _ = arg5;
@@ -390,28 +393,32 @@ fn testHandler2(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize)
     return 2;
 }
 
-fn testHandler3(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+fn testHandler3(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
     // Suppress unused variable warnings
+    _ = ctx;
     _ = arg4;
     _ = arg5;
     test_int += arg1 + arg2 + arg3;
     return 3;
 }
 
-fn testHandler4(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+fn testHandler4(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
     // Suppress unused variable warnings
+    _ = ctx;
     _ = arg5;
     test_int += arg1 + arg2 + arg3 + arg4;
     return 4;
 }
 
-fn testHandler5(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+fn testHandler5(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+    _ = ctx;
     test_int += arg1 + arg2 + arg3 + arg4 + arg5;
     return 5;
 }
 
-fn testHandler6(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
+fn testHandler6(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) anyerror!usize {
     // Suppress unused variable warnings
+    _ = ctx;
     _ = arg1;
     _ = arg2;
     _ = arg3;

src/kernel/syscalls.zig

@@ -2,6 +2,7 @@ const std = @import("std");
 const scheduler = @import("scheduler.zig");
 const panic = @import("panic.zig").panic;
 const log = std.log.scoped(.syscalls);
+const arch = @import("arch.zig").internals;
 
 /// A compilation of all errors that syscall handlers could return.
 pub const Error = error{OutOfMemory};
@@ -46,7 +47,7 @@ pub const Syscall = enum {
 };
 
 /// A function that can handle a syscall and return a result or an error
-pub const Handler = fn (arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize;
+pub const Handler = fn (ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize;
 
 ///
 /// Convert an error code to an instance of Error. The conversion must be synchronised with toErrorCode
@@ -88,12 +89,13 @@ pub fn toErrorCode(err: anyerror) u16 {
 /// Error: Error
 ///     The error raised by the handler
 ///
-pub fn handle(syscall: Syscall, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize {
+pub fn handle(syscall: Syscall, ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize {
-    return try syscall.getHandler()(arg1, arg2, arg3, arg4, arg5);
+    return try syscall.getHandler()(ctx, arg1, arg2, arg3, arg4, arg5);
 }
 
-pub fn handleTest1(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize {
+pub fn handleTest1(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize {
     // Suppress unused variable warnings
+    _ = ctx;
     _ = arg1;
     _ = arg2;
     _ = arg3;
@@ -102,12 +104,14 @@ pub fn handleTest1(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usi
     return 0;
 }
 
-pub fn handleTest2(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize {
+pub fn handleTest2(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize {
+    _ = ctx;
     return arg1 + arg2 + arg3 + arg4 + arg5;
 }
 
-pub fn handleTest3(arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize {
+pub fn handleTest3(ctx: *const arch.CpuState, arg1: usize, arg2: usize, arg3: usize, arg4: usize, arg5: usize) Error!usize {
     // Suppress unused variable warnings
+    _ = ctx;
     _ = arg1;
     _ = arg2;
     _ = arg3;
@@ -123,7 +127,8 @@ test "getHandler" {
 }
 
 test "handle" {
-    try std.testing.expectEqual(@as(usize, 0), try handle(.Test1, 0, 0, 0, 0, 0));
+    const state = arch.CpuState.empty();
-    try std.testing.expectEqual(@as(usize, 1 + 2 + 3 + 4 + 5), try handle(.Test2, 1, 2, 3, 4, 5));
+    try std.testing.expectEqual(@as(usize, 0), try handle(.Test1, &state, 0, 0, 0, 0, 0));
-    try std.testing.expectError(Error.OutOfMemory, handle(.Test3, 0, 0, 0, 0, 0));
+    try std.testing.expectEqual(@as(usize, 1 + 2 + 3 + 4 + 5), try handle(.Test2, &state, 1, 2, 3, 4, 5));
+    try std.testing.expectError(Error.OutOfMemory, handle(.Test3, &state, 0, 0, 0, 0, 0));
 }

test/mock/kernel/arch_mock.zig

@@ -54,6 +54,31 @@ pub const CpuState = struct {
     eflags: u32,
     user_esp: u32,
     user_ss: u32,
+
+    pub fn empty() CpuState {
+        return .{
+            .ss = undefined,
+            .gs = undefined,
+            .fs = undefined,
+            .es = undefined,
+            .ds = undefined,
+            .edi = undefined,
+            .esi = undefined,
+            .ebp = undefined,
+            .esp = undefined,
+            .ebx = undefined,
+            .edx = undefined,
+            .ecx = undefined,
+            .eax = undefined,
+            .int_num = undefined,
+            .error_code = undefined,
+            .eip = undefined,
+            .cs = undefined,
+            .eflags = undefined,
+            .user_esp = undefined,
+            .user_ss = undefined,
+        };
+    }
 };
 
 pub const VmmPayload = switch (builtin.cpu.arch) {