syscall: Convert VFS hook /process/create => launch(bytes: [*]align(@alignOf(std.elf.Elf64_Ehdr)) const u8, len: usize) !usize (#60)

2 files changed, 16 insertions, 152 deletions

diff --git a/src/lib/resources.zig b/src/lib/resources.zig
index 315fe57..7c6ca19 100644
--- a/src/lib/resources.zig
+++ b/src/lib/resources.zig
@@ -8,7 +8,6 @@ const Console = @import("Console.zig");
 const instructions = @import("instructions.zig");
 const mem = @import("mem.zig");
 const paging = @import("paging.zig");
-const process = @import("process.zig");
 const syscall = @import("syscall.zig");
 const sysexchange = @import("sysexchange.zig");
 const userinit = @import("userinit.zig");
@@ -51,142 +50,6 @@ const iofs = struct {
     };
 };
 
-const processfs = struct {
-    const CreationContext = struct {
-        rd: vfs.ResourceDescriptor,
-        buffer: std.ArrayListAligned(u8, paging.page_size),
-        proc: *process.Info,
-    };
-
-    fn create(pid: u16, thread_id: usize, data: usize) callconv(.C) Result(usize) {
-        const result = doCreate(pid, thread_id, data);
-        return Result(usize).fromAnyTypeOrError(result);
-    }
-
-    fn doCreate(pid: u16, thread_id: usize, data: usize) !usize {
-        paging.setUserMemoryAccess(true);
-        defer paging.setUserMemoryAccess(false);
-
-        const path_c: [*:0]const u8 = @ptrFromInt(data); // fixme: Kernel panic if null pointer
-
-        const allocator = mem.page_allocator;
-
-        const rd = try vfs.openNonHookZ(path_c);
-        defer rd.deinit();
-
-        if (rd.inode.resource.tag == .dir or rd.inode.resource.tag == .dir_hook) {
-            return vfs.Error.IsAContainer;
-        }
-
-        const proc = process.findThread(pid, thread_id).?;
-
-        var buffer = std.ArrayListAligned(u8, paging.page_size).init(allocator);
-        defer buffer.clearAndFree();
-
-        const ctx = try allocator.create(CreationContext);
-        defer allocator.destroy(ctx);
-
-        ctx.* = .{
-            .rd = rd,
-            .buffer = buffer,
-            .proc = proc,
-        };
-
-        paging.setUserMemoryAccess(false);
-
-        defer proc.allowResume();
-
-        try ctx.buffer.ensureUnusedCapacity(4096);
-
-        var unused_capacity = ctx.buffer.allocatedSlice()[ctx.buffer.items.len..];
-        var n = try rd.readHooked(proc, unused_capacity, .{
-            .hookFn = loadExe,
-            .context = ctx,
-        });
-
-        ctx.buffer.items.len += n;
-
-        while (n > 0) {
-            try buffer.ensureUnusedCapacity(4096);
-
-            unused_capacity = ctx.buffer.allocatedSlice()[ctx.buffer.items.len..];
-            n = try rd.readHooked(proc, unused_capacity, .{
-                .hookFn = loadExe,
-                .context = ctx,
-            });
-
-            ctx.buffer.items.len += n;
-        }
-
-        const new_proc = try process.create(allocator, ctx.buffer.items);
-        return new_proc.id;
-    }
-
-    fn loadExe(context: *anyopaque, driver: *const process.Info) void {
-        const ctx: *CreationContext = @alignCast(@ptrCast(context));
-        doLoadExe(ctx, driver) catch |err| {
-            sysexchange.frameReturn(usize, &ctx.proc.trap_frame, err);
-        };
-    }
-
-    fn doLoadExe(ctx: *CreationContext, driver: *const process.Info) !void {
-        const allocator = mem.page_allocator;
-
-        defer ctx.proc.allowResume();
-
-        const result: Result(usize) = .{
-            .value = driver.trap_frame.general_purpose_registers[12],
-            .status = @enumFromInt(driver.trap_frame.general_purpose_registers[13]),
-        };
-        if (result.status != .success) {
-            defer allocator.destroy(ctx);
-            defer ctx.buffer.clearAndFree();
-            defer ctx.rd.deinit();
-
-            sysexchange.frameReturnResult(usize, &ctx.proc.trap_frame, result);
-            return;
-        }
-
-        const n = result.value;
-        if (n == 0) {
-            defer allocator.destroy(ctx);
-            defer ctx.buffer.clearAndFree();
-            defer ctx.rd.deinit();
-
-            const new_proc = try process.create(allocator, ctx.buffer.items);
-            sysexchange.frameReturn(null, &ctx.proc.trap_frame, new_proc.id);
-            return;
-        }
-
-        ctx.buffer.items.len += n;
-
-        try ctx.buffer.ensureUnusedCapacity(4096);
-
-        var unused_capacity = ctx.buffer.allocatedSlice()[ctx.buffer.items.len..];
-        var n2 = try ctx.rd.readHooked(ctx.proc, unused_capacity, .{
-            .hookFn = loadExe,
-            .context = ctx,
-        });
-
-        ctx.buffer.items.len += n;
-
-        while (n2 > 0) {
-            try ctx.buffer.ensureUnusedCapacity(4096);
-
-            unused_capacity = ctx.buffer.allocatedSlice()[ctx.buffer.items.len..];
-            n2 = try ctx.rd.readHooked(ctx.proc, unused_capacity, .{
-                .hookFn = loadExe,
-                .context = ctx,
-            });
-
-            ctx.buffer.items.len += n2;
-        }
-
-        const new_proc = try process.create(allocator, ctx.buffer.items);
-        sysexchange.frameReturn(null, &ctx.proc.trap_frame, new_proc.id);
-    }
-};
-
 pub const Error = error{
     NoTarFileInitializer,
     NoConsole,
@@ -195,11 +58,9 @@ pub const Error = error{
 pub fn provideBuiltin(allocator: std.mem.Allocator) !void {
     try addDir("/io");
     try addDir("/userinit");
-    try addDir("/process");
 
     try provideConsole();
     try provideUserinit(allocator);
-    try provideProcess();
 }
 
 fn provideConsole() !void {
@@ -239,19 +100,6 @@ fn provideUserinit(allocator: std.mem.Allocator) !void {
     }
 }
 
-fn provideProcess() !void {
-    try vfs.provideResource("/process/create", .{
-        .tag = .hook,
-        .data = .{
-            .hook = .{
-                .callback = processfs.create,
-            },
-        },
-    }, 0, .{
-        .reclaimable = false,
-    });
-}
-
 fn addFile(path: []const u8, file: File) !void {
     const allocator = vfs.treeRoot().allocator;
 
diff --git a/src/lib/syscall.zig b/src/lib/syscall.zig
index 0767fbd..9841675 100644
--- a/src/lib/syscall.zig
+++ b/src/lib/syscall.zig
@@ -5,6 +5,7 @@
 const std = @import("std");
 
 const instructions = @import("instructions.zig");
+const mem = @import("mem.zig");
 const paging = @import("paging.zig");
 const process = @import("process.zig");
 const sysexchange = @import("sysexchange.zig");
@@ -37,6 +38,7 @@ pub fn handler(proc: *process.Info, trap_frame: *trap.Frame) !void {
         100012 => ret(null, trap_frame, terminate(proc)),
         100013 => ret(null, trap_frame, processId(proc)),
         100014 => ret(null, trap_frame, threadId(proc)),
+        100015 => ret(null, trap_frame, launch(trap_frame)),
         else => return HandleError.UnknownSyscall,
     }
 }
@@ -321,3 +323,17 @@ fn processId(proc: *const process.Info) usize {
 fn threadId(proc: *const process.Info) usize {
     return proc.thread_id;
 }
+
+// launch(bytes: [*]align(@alignOf(std.elf.Elf64_Ehdr)) const u8, len: usize) !usize
+fn launch(trap_frame: *const trap.Frame) !usize {
+    const alignment = @alignOf(std.elf.Elf64_Ehdr);
+    const bytes_addr = trap_frame.general_purpose_registers[10];
+    // fixme: Kernel panic if null pointer
+    const bytes_ptr: [*]align(alignment) const u8 = @ptrFromInt(bytes_addr);
+    const len = trap_frame.general_purpose_registers[11];
+
+    const bytes = bytes_ptr[0..len];
+
+    const new_proc = try process.create(mem.page_allocator, bytes);
+    return new_proc.id;
+}