syscall: Replace terminate() with /process/self/terminate VFS hook

5 files changed, 55 insertions, 14 deletions

diff --git a/src/lib/process.zig b/src/lib/process.zig
index d7ecd5f..85d6522 100644
--- a/src/lib/process.zig
+++ b/src/lib/process.zig
@@ -458,6 +458,21 @@ fn usizeFromArg(arg: anytype) usize {
     };
 }
 
+pub fn findThread(pid: u16, thread_id: usize) ?*Info {
+    var node = list.first;
+    while (node) |proc_node| : (node = proc_node.next) {
+        if (proc_node.data.id == pid and proc_node.data.thread_id == thread_id) {
+            return &proc_node.data;
+        }
+    }
+
+    return null;
+}
+
+pub fn mainThread(pid: u16) ?*Info {
+    return findThread(pid, 0);
+}
+
 pub fn latestThread(pid: u16) ?*Info {
     var latest: ?*Info = null;
 
diff --git a/src/lib/resources.zig b/src/lib/resources.zig
index f73c751..92a28b6 100644
--- a/src/lib/resources.zig
+++ b/src/lib/resources.zig
@@ -45,6 +45,18 @@ const iofs = struct {
     };
 };
 
+const processfs = struct {
+    const self = struct {
+        fn terminate(pid: u16, thread_id: usize, _: usize) callconv(.C) sysexchange.Result(usize) {
+            const proc = process.findThread(pid, thread_id).?;
+            proc.terminate();
+            process.schedule() catch |err| {
+                std.debug.panic("Unable to schedule because all processes are terminated: {any}", .{err});
+            };
+        }
+    };
+};
+
 pub const Error = error{
     NoTarFileInitializer,
     NoConsole,
@@ -53,9 +65,12 @@ pub const Error = error{
 pub fn provideBuiltin() !void {
     try addDir("/io");
     try addDir("/userinit");
+    try addDir("/process");
+    try addDir("/process/self");
 
     try provideConsole();
     try provideUserinit();
+    try provideProcessSelf();
 }
 
 fn provideConsole() !void {
@@ -95,6 +110,19 @@ fn provideUserinit() !void {
     }
 }
 
+fn provideProcessSelf() !void {
+    try vfs.provideResource("/process/self/terminate", .{
+        .tag = .hook,
+        .data = .{
+            .hook = .{
+                .callback = processfs.self.terminate,
+            },
+        },
+    }, 0, .{
+        .reclaimable = false,
+    });
+}
+
 fn addFile(path: []const u8, file: File) !void {
     const allocator = vfs.treeRoot().allocator;
 
diff --git a/src/lib/rethooks.zig b/src/lib/rethooks.zig
index bad4d55..e81125a 100644
--- a/src/lib/rethooks.zig
+++ b/src/lib/rethooks.zig
@@ -3,9 +3,16 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
 pub fn terminate() linksection(".rethooks") callconv(.Naked) noreturn {
-    // Syscall #100011 is "terminate".
+    // Syscall #100001 is "open".
+    // Use the "/process/self/terminate" hook to terminate the thread.
     asm volatile (
-        \\ li a7, 100011
+        \\ mv a0, a2
+        \\ mv a1, a3
+        \\ mv t0, a0
+        \\ li a7, 100001
         \\ ecall
+        :
+        : [path_c] "{t0}" ("/process/self/terminate\x00".ptr),
+        : "a0", "a2", "a3", "a7"
     );
 }
diff --git a/src/lib/syscall.zig b/src/lib/syscall.zig
index 1533cd4..5cbc9f2 100644
--- a/src/lib/syscall.zig
+++ b/src/lib/syscall.zig
@@ -32,7 +32,6 @@ pub fn handler(proc: *process.Info, trap_frame: *trap.Frame) !void {
         100008 => remove(trap_frame),
         100009 => read(proc, trap_frame),
         100010 => write(proc, trap_frame),
-        100011 => terminate(proc),
         else => return HandleError.UnknownSyscall,
     }
 }
@@ -269,11 +268,3 @@ fn write(proc: *process.Info, trap_frame: *trap.Frame) void {
     };
     sysexchange.frameReturn(usize, trap_frame, result);
 }
-
-// terminate() noreturn
-fn terminate(proc: *process.Info) noreturn {
-    proc.terminate();
-    process.schedule() catch |err| {
-        std.debug.panic("Unable to schedule because all processes are terminated: {any}", .{err});
-    };
-}
diff --git a/src/lib/vfs.zig b/src/lib/vfs.zig
index 71dda98..46f01d6 100644
--- a/src/lib/vfs.zig
+++ b/src/lib/vfs.zig
@@ -72,7 +72,7 @@ pub const File = extern struct {
 pub const Hook = extern struct {
     callback: Callback,
 
-    pub const Callback = *allowzero const fn (pid: u16, data: usize) callconv(.C) sysexchange.Result(usize);
+    pub const Callback = *allowzero const fn (pid: u16, thread_id: usize, data: usize) callconv(.C) sysexchange.Result(usize);
 };
 
 // A directory hook is a resource that provides other resources via driver callbacks.
@@ -380,8 +380,8 @@ fn call(proc: *process.Info, function: *const anyopaque, args: anytype, cleanup_
 
 fn crossProcessReturn(context: *anyopaque, driver: *const process.Info) void {
     const proc: *process.Info = @alignCast(@ptrCast(context));
-    proc.trap_frame.general_purpose_registers[10] = driver.trap_frame.general_purpose_registers[10];
-    proc.trap_frame.general_purpose_registers[11] = driver.trap_frame.general_purpose_registers[11];
+    proc.trap_frame.general_purpose_registers[10] = driver.trap_frame.general_purpose_registers[12];
+    proc.trap_frame.general_purpose_registers[11] = driver.trap_frame.general_purpose_registers[13];
     proc.pc += 4; // Skip ecall instruction
     proc.state = .waiting;
     // Scheduler is called by the "terminate" syscall after two layers of returning.