commit c9b9b1c6153d074a929165ed5a746bd962a294f5 · pci.express/frostium

+4 -3

components/root_server/src/main.zig

···

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       export fn _start() callconv(.c) noreturn {

     

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           _ = os.syscall1(SYS_poke, 0xB16B00B5BADBABE);

     

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       -
           _ = os.syscall1(SYS_exit, 0);

     

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           _ = os.syscall1(SYS_exit, 0x69696969);

     

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       +
       

     

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           unreachable;

     

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       }

     

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       -
       pub const SYS_exit = 69;

     

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       pub const SYS_poke = 420;

     

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       pub const SYS_exit = 0x420;

     

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       pub const SYS_poke = 0x69;

+2 -2

components/root_server/src/os.zig

···

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           pub fn syscall1(number: usize, arg1: usize) usize {

     

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               return asm volatile ("syscall"

     

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                   : [ret] "={rax}" (-> usize),

     

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                   : [number] "{rax}" (number),

     

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                     [arg1] "{rdi}" (arg1),

     

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                   : [number] "{rdi}" (number),

     

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                     [arg1] "{rsi}" (arg1),

     

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                   : .{ .rcx = true, .r11 = true });

     

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           }

     

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       };

+11 -35

components/ukernel/arch/amd64/boot.zig

···

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           log.info("Allocating code for userspace...", .{});

     

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           const user_code = common.init_data.bootmem.allocPhys(0x1000) catch @panic("alloc bruh");

     

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           const user_stack = common.init_data.bootmem.allocPhys(0x1000) catch @panic("alloc bruh2");

     

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           // TODO: load the actual root task ELF for fucks sake

     

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           // instead of the current glorified shellcode

     

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           // Map our executable page to 0x1000

     

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           common.mm.paging.mapPhys(.{

     

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               .vaddr = 0x8000,

     

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               .paddr = user_code,

     

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               .size = 0x1000,

     

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               .memory_type = .MemoryWriteBack,

     

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               .perms = .{

     

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                   .executable = true,

     

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                   .writable = false,

     

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                   .userspace_accessible = true,

     

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               },

     

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           }) catch {

     

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               @panic("Mapping failed!!!!!");

     

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           };

     

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           // Map our stack page to 0x3000 (starts at 0x4000)

     

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           common.mm.paging.mapPhys(.{

     

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           // Allocate a stack (0x3000 - 0x4000)

     

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           common.mm.paging.map(.{

     

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               .vaddr = 0x3000,

     

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               .paddr = user_stack,

     

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               .size = 0x1000,

     

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               .memory_type = .MemoryWriteBack,

     

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               .perms = .{

     

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                   .executable = false,

     

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                   .writable = true,

     

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                   .userspace_accessible = true,

     

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                   .writable = true,

     

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               },

     

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           }) catch {

     

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               @panic("Mapping failed!!!!!");

     

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           };

     

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           }) catch @panic("couldn't map user stack");

     

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           // Place shellcode there (does a couple syscalls then jmp $ infinite loop)

     

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           const memory: [*]u8 = common.mm.physToHHDM([*]u8, user_code);

     

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           const shellcode = [_]u8{ 0x48, 0xBF, 0xE1, 0xAB, 0xDB, 0xBA, 0xB5, 0x00, 0x6B, 0xB1, 0x48, 0xBE, 0x06, 0x42, 0x69, 0x20, 0x94, 0x06, 0x42, 0x69, 0x0F, 0x05, 0xBF, 0x11, 0xCA, 0x00, 0x00, 0xBE, 0x69, 0x69, 0x69, 0x69, 0x0F, 0x05, 0xEB, 0xFE };

     

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           @memcpy(memory[0..@sizeOf(@TypeOf(shellcode))], shellcode[0..]);

     

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           const entry = common.loadRootTask() catch |err| {

     

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               log.err("Couldn't load the root task! {}", .{err});

     

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               @panic("ggz");

     

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           };

     

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           log.info("Dropping to userspace entry 0x{x:0>16}", .{entry});

     

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           // Set up MSRs to enable syscalls

     

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           init_syscalls();

     

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           // Finally, iretq ourselves into this bitch

     

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           enter_userspace(0x8000, 0x69, 0x3800);

     

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           enter_userspace(entry, 0x69, 0x4000);

     

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       }

     

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       // Get ready for system calls (set MSRs)

     
···

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       });

     

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       export fn syscall_handler(rdi: usize, rsi: usize) callconv(.c) void {

     

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           std.log.info("Got a syscall! rdi=0x{x}, rsi=0x{x}", .{ rdi, rsi });

     

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           if (rdi == 0x420) arch.instructions.die();

     

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       }

     

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       fn enter_userspace(entry: u64, arg: u64, stack: u64) noreturn {

+52

components/ukernel/common/loader.zig

···

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       +
       const common = @import("root.zig");

     

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       const paging = common.mm.paging;

     

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       const std = @import("std");

     

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       const elf = std.elf;

     

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       const log = std.log.scoped(.elf_loader);

     

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       // Load root task, return the entry point

     

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       pub fn loadRootTask() !usize {

     

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           const root_task = common.init_data.root_task;

     

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           const hdr = blk: {

     

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               const hdr: *elf.Elf64_Ehdr = @ptrCast(root_task);

     

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               break :blk elf.Header.init(hdr.*, .little);

     

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           };

     

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           var iter = hdr.iterateProgramHeadersBuffer(root_task);

     

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           while (try iter.next()) |entry| {

     

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               if ((entry.p_type != elf.PT_LOAD) or (entry.p_memsz == 0)) continue;

     

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               // 1. Allocate pages to back this allocation

     

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               const real_vaddr = std.mem.alignBackward(usize, entry.p_vaddr, std.heap.pageSize());

     

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               const vaddr_shift = entry.p_vaddr - real_vaddr;

     

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               const memsz_pages = std.mem.alignForward(usize, vaddr_shift + entry.p_memsz, std.heap.pageSize());

     

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               log.debug("Allocating 0x{x} bytes (0x{x} real) to 0x{x:0>16} from offset 0x{x}", .{ entry.p_filesz, memsz_pages, entry.p_vaddr, entry.p_offset });

     

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               const page_backing = try common.init_data.bootmem.allocPhys(memsz_pages);

     

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               try paging.mapPhys(.{

     

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                   .vaddr = real_vaddr,

     

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                   .paddr = page_backing,

     

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                   .size = memsz_pages,

     

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                   .memory_type = .MemoryWriteBack,

     

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                   .perms = .{

     

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                       .executable = entry.p_flags & elf.PF_X > 0,

     

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                       .writable = entry.p_flags & elf.PF_W > 0,

     

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                       .userspace_accessible = true,

     

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                   },

     

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               });

     

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               // 2. Copy filesz bytes from offset to this new page

     

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               const dst = common.mm.physToHHDM([*]u8, page_backing + vaddr_shift);

     

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               const dst_slice = dst[0..entry.p_filesz];

     

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               const src_slice = root_task[entry.p_offset..][0..entry.p_filesz];

     

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               @memcpy(dst_slice, src_slice);

     

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               // 3. Add memsz - filesz zeroes

     

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               const zero_slice = dst[entry.p_filesz..entry.p_memsz];

     

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               @memset(zero_slice, 0);

     

       48
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           }

     

       49
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       +
       

     

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           // Return the entry point

     

       51
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           return hdr.entry;

     

       52
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       }

+12

components/ukernel/common/mm/paging.zig

···

       50
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           try mapPageImpl(&vaddr, &paddr, &size, root, args.perms, args.memory_type);

     

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       }

     

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       53
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       pub fn map(args: struct {

     

       54
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           vaddr: usize,

     

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           size: usize,

     

       56
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           perms: Perms,

     

       57
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           memory_type: MemoryType,

     

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       +
       }) !void {

     

       59
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           const root = arch.mm.paging.root_table(args.vaddr);

     

       60
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           var vaddr = args.vaddr;

     

       61
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           var size = args.size;

     

       62
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           try mapPageImpl(&vaddr, null, &size, root, args.perms, args.memory_type);

     

       63
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       +
       }

     

       64
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       +
       

     

       53
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       fn mapPageImpl(

     

       54
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           vaddr: *usize,

     

       55
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           paddr: ?*usize,

components/ukernel/common/root.zig

···

       1
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       pub const aux = @import("aux.zig");

     

       2
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       pub const mm = @import("mm/root.zig");

     

       3
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       +
       pub const loadRootTask = loader.loadRootTask;

     

       4
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       const loader = @import("loader.zig");

     

       3
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       4
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       // Arch init must set up appropriate fields!

     

       5
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       pub var init_data: aux.InitState = .{};