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-rw-r--r--kernel/sys_misc.cc360
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diff --git a/kernel/sys_misc.cc b/kernel/sys_misc.cc
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-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-/*
- * Miscellaneous System Calls — busybox bootstrap set
- *
- * Each syscall follows the Linux kernel semantics exactly.
- * Reference: Linux kernel/sys.c, kernel/signal.c, kernel/time/posix-timers.c
- */
-
-#include <lume/types.h>
-#include <lume/task.h>
-#include <lume/errno.h>
-#include <lume/kprintf.h>
-#include <lume/klog.h>
-#include <lume/pid.h>
-#include <lume/pgrp.h>
-#include <lume/signal_types.h>
-#include <lume/tty.h>
-#include <lume/uaccess.h>
-#include <arch/cpu.h>
-
-/* ======================================================================
- * sys_reboot — Linux kernel/reboot.c
- *
- * Validates magic numbers and performs the requested action.
- * For now, we only support LINUX_REBOOT_CMD_CAD_ON/OFF (ignore)
- * and reject everything else with -EPERM (no CAP_SYS_BOOT).
- * ====================================================================== */
-
-static constexpr uint32 LINUX_REBOOT_MAGIC1 = 0xfee1dead;
-static constexpr uint32 LINUX_REBOOT_MAGIC2 = 672274793; /* 0x28121969 */
-static constexpr uint32 LINUX_REBOOT_MAGIC2A = 85072278;
-static constexpr uint32 LINUX_REBOOT_MAGIC2B = 369367448;
-static constexpr uint32 LINUX_REBOOT_MAGIC2C = 537993216;
-
-int64 sys_reboot(uint64 magic1, uint64 magic2, uint64 cmd,
- uint64, uint64, uint64)
-{
- /* Linux: kernel/reboot.c — validate magic numbers first */
- if (static_cast<uint32>(magic1) != LINUX_REBOOT_MAGIC1)
- return -EINVAL;
- if (static_cast<uint32>(magic2) != LINUX_REBOOT_MAGIC2 &&
- static_cast<uint32>(magic2) != LINUX_REBOOT_MAGIC2A &&
- static_cast<uint32>(magic2) != LINUX_REBOOT_MAGIC2B &&
- static_cast<uint32>(magic2) != LINUX_REBOOT_MAGIC2C)
- return -EINVAL;
-
- /* We don't have CAP_SYS_BOOT yet — reject with -EPERM.
- * This matches Linux behavior for unprivileged callers.
- * Busybox handles this gracefully and continues. */
- (void)cmd;
- printk(KERN_INFO "reboot: cmd=%llu (not implemented, returning -EPERM)\n", cmd);
- return -EPERM;
-}
-
-/* ======================================================================
- * sys_prctl — Linux kernel/sys.c
- *
- * Process control. Most options are optional for early boot.
- * We implement the minimum set busybox needs.
- * ====================================================================== */
-
-/* prctl option constants (from <linux/prctl.h>) */
-static constexpr int PR_SET_NAME = 15;
-static constexpr int PR_GET_NAME = 16;
-static constexpr int PR_SET_PDEATHSIG = 1;
-static constexpr int PR_GET_PDEATHSIG = 2;
-
-int64 sys_prctl(uint64 option, uint64 arg2, uint64 arg3,
- uint64 arg4, uint64 arg5, uint64)
-{
- switch (static_cast<int>(option)) {
- case PR_SET_PDEATHSIG:
- /* Linux: set signal delivered when parent dies.
- * Silently accept — we don't track pdeath_signal yet. */
- return 0;
- case PR_GET_PDEATHSIG: {
- /* Linux: return current pdeath_signal (0 = none) */
- int32 zero = 0;
- if (copy_to_user(arg2, &zero, sizeof(zero)) != 0)
- return -EFAULT;
- return 0;
- }
- case PR_SET_NAME: {
- /* Linux: set comm (task name), max 16 chars */
- /* TODO: copy_from_user the string */
- return 0;
- }
- case PR_GET_NAME: {
- /* Linux: get comm (task name) */
- TaskControlBlock* curr = current_task();
- if (!curr) return -ESRCH;
- const char* name = curr->name ? curr->name : "";
- uint64 len = 0;
- while (name[len] && len < 15) len++;
- char buf[16] = {};
- for (uint64 i = 0; i < len; i++) buf[i] = name[i];
- if (copy_to_user(arg2, buf, 16) != 0)
- return -EFAULT;
- return 0;
- }
- default:
- /* Unknown prctl — Linux returns -EINVAL for unrecognized options */
- return -EINVAL;
- }
-}
-
-/* ======================================================================
- * Session / Process-Group syscalls
- *
- * All four operate on the caller's signal_struct (or a target task's).
- * Identity lives in signal_struct, so these become straightforward reads
- * and pgrp-hash updates. We mirror Linux kernel/sys.c semantics closely.
- * ====================================================================== */
-
-static TaskControlBlock* find_task_by_pid(int32 pid)
-{
- extern list_node g_all_tasks;
- extern Spinlock g_task_list_lock;
- LockGuard guard(g_task_list_lock);
- list_node* node = g_all_tasks.next;
- while (node != &g_all_tasks) {
- auto* task = list_entry<TaskControlBlock, &TaskControlBlock::all_link>(node);
- if (task->pid == pid) return task;
- node = node->next;
- }
- return nullptr;
-}
-
-/*
- * sys_setsid — Linux kernel/sys.c:ksys_setsid()
- *
- * Caller becomes leader of a new session+pgrp. Refused if a pgrp with
- * id == caller pid already exists with members other than the caller —
- * that's Linux's "process group id already exists" check, which prevents
- * collisions when a non-leader tries to setsid.
- */
-int64 sys_setsid(uint64, uint64, uint64, uint64, uint64, uint64)
-{
- TaskControlBlock* curr = current_task();
- if (!curr || !curr->signal) return -ESRCH;
-
- /* Detect collision: another pgrp already uses our pid as pgid. */
- bool conflict = false;
- for_each_pgrp_member(curr->pid, [&](signal_struct* sig) {
- if (sig != curr->signal) conflict = true;
- });
- if (conflict) return -EPERM;
-
- /* Move to new pgrp (creates one if missing), update sid, drop ctty. */
- change_pgid(curr->signal, curr->pid);
-
- /* Detach the controlling terminal. If this task is the session
- * leader that owns the tty (tty->session == caller's old sid),
- * also clear the tty's session/pgrp so the next session-leader
- * that opens the device can claim it. Without this, tty->session
- * permanently sticks to the abandoned sid and every subsequent
- * tty_acquire_ctty() bails with "owned by another session" —
- * which is exactly what kept BusyBox's child sh from picking the
- * console back up after init's setsid().
- *
- * Linux's behavior is similar in spirit (disassociate_ctty when
- * the leader exits), but it triggers from exit, not setsid. Our
- * simpler "clear-on-give-up" matches the way our acquisition path
- * is written. */
- tty_struct* old_tty = nullptr;
- int32 old_sid = 0;
- {
- LockGuard guard(curr->signal->lock);
- old_tty = curr->signal->tty;
- old_sid = curr->signal->sid;
- curr->signal->sid = curr->pid;
- curr->signal->tty = nullptr;
- curr->signal->tty_old_pgrp = 0;
- }
- if (old_tty) {
- LockGuard guard(old_tty->lock);
- if (old_tty->session == old_sid) {
- old_tty->session = 0;
- old_tty->pgrp = 0;
- }
- }
- return curr->pid;
-}
-
-/*
- * sys_setpgid — Linux kernel/sys.c:ksys_setpgid()
- *
- * Move a process between groups within the same session. Allowed:
- * - caller targeting self or a child
- * - target is not a session leader
- * - target stays in caller's session
- * - target hasn't exec()'d (we don't track did_exec yet, so skip)
- * - new pgid is either == target's pid (new group) or names a pgrp
- * that already exists in the same session
- */
-int64 sys_setpgid(uint64 pid, uint64 pgid, uint64, uint64, uint64, uint64)
-{
- TaskControlBlock* curr = current_task();
- if (!curr || !curr->signal) return -ESRCH;
-
- int32 target_pid = static_cast<int32>(pid);
- int32 target_pgid = static_cast<int32>(pgid);
-
- if (target_pid == 0) target_pid = curr->pid;
- if (target_pgid == 0) target_pgid = target_pid;
- if (target_pgid < 0) return -EINVAL;
-
- TaskControlBlock* target = (target_pid == curr->pid)
- ? curr
- : find_task_by_pid(target_pid);
- if (!target || !target->signal) return -ESRCH;
-
- /* Target must be caller or a child of caller. */
- if (target != curr && target->parent != curr) return -ESRCH;
-
- /* Same session as caller. */
- if (target->signal->sid != curr->signal->sid) return -EPERM;
-
- /* Cannot move a session leader into a different pgrp. */
- if (target->signal->sid == target->pid) return -EPERM;
-
- /* If target_pgid != target_pid, the pgrp must already exist in
- * the same session. pgrp existence == any signal_struct with
- * pgid == target_pgid AND sid == caller's sid. */
- if (target_pgid != target->pid) {
- bool found = false;
- for_each_pgrp_member(target_pgid, [&](signal_struct* sig) {
- if (sig->sid == curr->signal->sid) found = true;
- });
- if (!found) return -EPERM;
- }
-
- change_pgid(target->signal, target_pgid);
- return 0;
-}
-
-/*
- * sys_getpgid — return process group ID of `pid` (0 = self).
- */
-int64 sys_getpgid(uint64 pid, uint64, uint64, uint64, uint64, uint64)
-{
- TaskControlBlock* curr = current_task();
- if (!curr || !curr->signal) return -ESRCH;
-
- if (pid == 0) return curr->signal->pgid;
-
- TaskControlBlock* target = find_task_by_pid(static_cast<int32>(pid));
- if (!target || !target->signal) return -ESRCH;
- return target->signal->pgid;
-}
-
-/*
- * sys_getsid — return session ID of `pid` (0 = self).
- */
-int64 sys_getsid(uint64 pid, uint64, uint64, uint64, uint64, uint64)
-{
- TaskControlBlock* curr = current_task();
- if (!curr || !curr->signal) return -ESRCH;
-
- if (pid == 0) return curr->signal->sid;
-
- TaskControlBlock* target = find_task_by_pid(static_cast<int32>(pid));
- if (!target || !target->signal) return -ESRCH;
-
- /* Linux: -EPERM if target's session differs from caller's and we're
- * in a different namespace. We have one namespace, so always allow. */
- return target->signal->sid;
-}
-
-/* ======================================================================
- * sys_geteuid / sys_getegid — Linux kernel/sys.c
- *
- * Return effective UID/GID. We run everything as root (0).
- * ====================================================================== */
-
-int64 sys_geteuid(uint64, uint64, uint64, uint64, uint64, uint64)
-{
- /* Linux: return current_euid(). We are always root. */
- return 0;
-}
-
-int64 sys_getegid(uint64, uint64, uint64, uint64, uint64, uint64)
-{
- /* Linux: return current_egid(). We are always root. */
- return 0;
-}
-
-/* ======================================================================
- * sys_sigaltstack — Linux kernel/signal.c
- *
- * Set/get alternate signal stack. For now, accept and ignore
- * (busybox doesn't critically need it for shell operation).
- * ====================================================================== */
-
-int64 sys_sigaltstack(uint64 uss_ptr, uint64 uoss_ptr,
- uint64, uint64, uint64, uint64)
-{
- /* Linux: if uoss != NULL, return current alt stack info.
- * We don't have alt stacks yet — report SS_DISABLE. */
- if (uoss_ptr != 0) {
- /* stack_t { void* ss_sp; int ss_flags; size_t ss_size; }
- * On RISC-V LP64: 8 + 4 + padding + 8 = 24 bytes typically,
- * but the ABI packs it as {uint64, int32, pad, uint64}. */
- struct {
- uint64 ss_sp;
- int32 ss_flags;
- int32 _pad;
- uint64 ss_size;
- } oss = { 0, 2 /* SS_DISABLE */, 0, 0 };
- if (copy_to_user(uoss_ptr, &oss, sizeof(oss)) != 0)
- return -EFAULT;
- }
-
- /* uss: silently accept (we'll need it for proper signal handling later) */
- (void)uss_ptr;
- return 0;
-}
-
-/* ======================================================================
- * sys_clock_gettime — Linux kernel/time/posix-timers.c
- *
- * Get the current time for a given clock.
- * We use the RISC-V cycle counter as a monotonic source.
- * ====================================================================== */
-
-static constexpr int CLOCK_REALTIME = 0;
-static constexpr int CLOCK_MONOTONIC = 1;
-
-int64 sys_clock_gettime(uint64 clk_id, uint64 tp_ptr,
- uint64, uint64, uint64, uint64)
-{
- if (tp_ptr == 0) return -EFAULT;
-
- /* Read RISC-V time CSR (mtime mapped to SBI) */
- uint64 ticks = arch::cpu::read_time();
-
- /* Convert to seconds + nanoseconds.
- * QEMU virt timebase-frequency is 10MHz. */
- constexpr uint64 kTimebaseHz = 10'000'000ULL;
- uint64 sec = ticks / kTimebaseHz;
- uint64 nsec = (ticks % kTimebaseHz) * (1'000'000'000ULL / kTimebaseHz);
-
- struct timespec64 {
- int64 tv_sec;
- int64 tv_nsec;
- };
-
- timespec64 ts;
- ts.tv_sec = static_cast<int64>(sec);
- ts.tv_nsec = static_cast<int64>(nsec);
-
- (void)clk_id; /* We treat all clocks as monotonic for now */
-
- if (copy_to_user(tp_ptr, &ts, sizeof(ts)) != 0)
- return -EFAULT;
-
- return 0;
-}
generated by cgit v1.2.3 (git 2.46.0) at 2026-10-29 00:36:02 +0000