Daniel Samson
0a8c81b17a
Add lib/ — the shared user-space runtime every user binary links against (init now, servers/drivers later): syscall wrappers, the heap, IPC stub, and the process start shim. - lib/heap.zig: the kernel first-fit free-list ported to user space, grown via the mmap syscall instead of pmm+mapPage. Dual API over one global free list: extern "C" malloc/free/calloc/realloc (C ABI for future C code) and a std.mem.Allocator adapter (with in-place resize) for Zig std containers. - lib/syscall.zig + sys.zig: raw syscall0..5 (arg3 in r10) and typed yield/write/sleep/exit/mmap/munmap over danos.Syscall. - lib/start.zig: naked _start -> rt_start -> root.main() (SysV realign via call), panic -> exit(127). - lib/user.ld: the user link script, moved from sbin/linker.ld (shared by all user binaries). - build.zig: register the `rt` module; add an addUserBinary() helper that is the one recipe for every user binary (freestanding, .large, use_lld, user.ld, image_base), replacing the bespoke init block. - sbin/init.zig: migrated onto rt; drops its hand-rolled syscall2/shims. Now proves the heap (alloc -> write from a heap pointer -> free) before the heartbeat loop. Serial shows "init: heap ok". Suite 28/28.
53 lines
1.9 KiB
Zig
53 lines
1.9 KiB
Zig
//! Typed syscall surface for user space — thin wrappers over the raw `syscall`
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//! stubs, one per kernel call. Numbers come from `danos.Syscall`, the single
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//! source of truth shared with the kernel dispatcher.
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const danos = @import("danos");
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const sc = @import("syscall.zig");
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/// `mmap` protection flags (matching the usual C bit values). Grants are always
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/// readable+writable today; the kernel does not yet honour finer prot.
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pub const PROT_READ: usize = danos.prot_read;
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pub const PROT_WRITE: usize = danos.prot_write;
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pub const PROT_EXEC: usize = danos.prot_exec;
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/// Give up the rest of this quantum.
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pub fn yield() void {
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_ = sc.syscall0(.yield);
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}
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/// Write raw bytes to the kernel log (a bring-up diagnostic; real output goes
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/// through the console/VFS later). Returns the byte count, or a wrapped -1.
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pub fn write(msg: []const u8) usize {
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return sc.syscall2(.debug_write, @intFromPtr(msg.ptr), msg.len);
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}
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/// Block the caller for `ms` milliseconds.
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pub fn sleep(ms: usize) void {
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_ = sc.syscall1(.sleep, ms);
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}
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/// End the process. Never returns.
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pub fn exit(code: usize) noreturn {
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_ = sc.syscall1(.exit, code);
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unreachable; // the kernel never returns from exit
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}
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/// Grant `len` bytes (rounded up to whole pages) of fresh, zeroed, writable
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/// memory and return the base virtual address. On failure returns a value in the
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/// top page (see `mmapFailed`). The user heap grows through this call.
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pub fn mmap(len: usize, prot: usize) usize {
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return sc.syscall2(.mmap, len, prot);
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}
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/// Release a range previously handed out by `mmap`.
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pub fn munmap(base: usize, len: usize) usize {
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return sc.syscall2(.munmap, base, len);
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}
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/// Whether an `mmap` return value is an error (the kernel returns a wrapped
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/// -errno, which lands in the top page — no real grant base is ever that high).
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pub inline fn mmapFailed(ret: usize) bool {
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return ret > ~@as(usize, 0) - 4095;
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}
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