394 lines
11 KiB
C
394 lines
11 KiB
C
/*-
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* SPDX-License-Identifier: BSD-4-Clause
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*
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* Copyright (C) 1994, David Greenman
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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* Copyright (c) 2007, 2022 The FreeBSD Foundation
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*
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* This code is derived from software contributed to Berkeley by
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* the University of Utah, and William Jolitz.
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*
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* Portions of this software were developed by A. Joseph Koshy under
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* sponsorship from the FreeBSD Foundation and Google, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)trap.c 7.4 (Berkeley) 5/13/91
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_hwpmc_hooks.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/limits.h>
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#include <sys/lock.h>
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#include <sys/msan.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/ktr.h>
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#include <sys/resourcevar.h>
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#include <sys/sched.h>
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#include <sys/syscall.h>
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#include <sys/syscallsubr.h>
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#include <sys/sysent.h>
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#include <sys/systm.h>
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#include <sys/vmmeter.h>
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#include <machine/cpu.h>
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#ifdef VIMAGE
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#include <net/vnet.h>
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#endif
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#ifdef HWPMC_HOOKS
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#include <sys/pmckern.h>
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#endif
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#ifdef EPOCH_TRACE
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#include <sys/epoch.h>
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#endif
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/*
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* Define the code needed before returning to user mode, for trap and
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* syscall.
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*/
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void
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userret(struct thread *td, struct trapframe *frame)
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{
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struct proc *p = td->td_proc;
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CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
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td->td_name);
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KASSERT((p->p_flag & P_WEXIT) == 0,
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("Exiting process returns to usermode"));
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#ifdef DIAGNOSTIC
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/*
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* Check that we called signotify() enough. For
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* multi-threaded processes, where signal distribution might
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* change due to other threads changing sigmask, the check is
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* racy and cannot be performed reliably.
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* If current process is vfork child, indicated by P_PPWAIT, then
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* issignal() ignores stops, so we block the check to avoid
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* classifying pending signals.
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*/
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if (p->p_numthreads == 1) {
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PROC_LOCK(p);
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thread_lock(td);
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if ((p->p_flag & P_PPWAIT) == 0 &&
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(td->td_pflags & TDP_SIGFASTBLOCK) == 0 &&
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SIGPENDING(td) && !td_ast_pending(td, TDA_AST) &&
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!td_ast_pending(td, TDA_SIG)) {
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thread_unlock(td);
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panic(
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"failed to set signal flags for ast p %p "
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"td %p td_ast %#x fl %#x",
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p, td, td->td_ast, td->td_flags);
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}
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thread_unlock(td);
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PROC_UNLOCK(p);
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}
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#endif
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/*
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* Charge system time if profiling.
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*/
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if (__predict_false(p->p_flag & P_PROFIL))
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addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
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#ifdef HWPMC_HOOKS
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if (PMC_THREAD_HAS_SAMPLES(td))
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PMC_CALL_HOOK(td, PMC_FN_THR_USERRET, NULL);
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#endif
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#ifdef TCPHPTS
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/*
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* @gallatin is adament that this needs to go here, I
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* am not so sure. Running hpts is a lot like
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* a lro_flush() that happens while a user process
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* is running. But he may know best so I will go
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* with his view of accounting. :-)
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*/
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tcp_run_hpts();
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#endif
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/*
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* Let the scheduler adjust our priority etc.
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*/
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sched_userret(td);
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/*
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* Check for misbehavior.
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*
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* In case there is a callchain tracing ongoing because of
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* hwpmc(4), skip the scheduler pinning check.
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* hwpmc(4) subsystem, infact, will collect callchain informations
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* at ast() checkpoint, which is past userret().
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*/
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WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
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KASSERT(td->td_critnest == 0,
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("userret: Returning in a critical section"));
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KASSERT(td->td_locks == 0,
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("userret: Returning with %d locks held", td->td_locks));
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KASSERT(td->td_rw_rlocks == 0,
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("userret: Returning with %d rwlocks held in read mode",
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td->td_rw_rlocks));
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KASSERT(td->td_sx_slocks == 0,
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("userret: Returning with %d sx locks held in shared mode",
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td->td_sx_slocks));
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KASSERT(td->td_lk_slocks == 0,
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("userret: Returning with %d lockmanager locks held in shared mode",
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td->td_lk_slocks));
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KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
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("userret: Returning with pagefaults disabled"));
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if (__predict_false(!THREAD_CAN_SLEEP())) {
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#ifdef EPOCH_TRACE
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epoch_trace_list(curthread);
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#endif
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KASSERT(0, ("userret: Returning with sleep disabled"));
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}
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KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
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("userret: Returning with pinned thread"));
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KASSERT(td->td_vp_reserved == NULL,
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("userret: Returning with preallocated vnode"));
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KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0,
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("userret: Returning with stop signals deferred"));
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KASSERT(td->td_vslock_sz == 0,
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("userret: Returning with vslock-wired space"));
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#ifdef VIMAGE
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/* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
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VNET_ASSERT(curvnet == NULL,
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("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
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__func__, td, p->p_pid, td->td_name, curvnet,
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(td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
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#endif
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}
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static void
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ast_prep(struct thread *td, int tda __unused)
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{
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VM_CNT_INC(v_trap);
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td->td_pticks = 0;
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if (td->td_cowgen != atomic_load_int(&td->td_proc->p_cowgen))
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thread_cow_update(td);
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}
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struct ast_entry {
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int ae_flags;
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int ae_tdp;
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void (*ae_f)(struct thread *td, int ast);
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};
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_Static_assert(TDAI(TDA_MAX) <= UINT_MAX, "Too many ASTs");
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static struct ast_entry ast_entries[TDA_MAX] __read_mostly = {
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[TDA_AST] = { .ae_f = ast_prep, .ae_flags = ASTR_UNCOND},
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};
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void
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ast_register(int ast, int flags, int tdp,
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void (*f)(struct thread *, int asts))
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{
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struct ast_entry *ae;
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MPASS(ast < TDA_MAX);
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MPASS((flags & ASTR_TDP) == 0 || ((flags & ASTR_ASTF_REQUIRED) != 0
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&& __bitcount(tdp) == 1));
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ae = &ast_entries[ast];
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MPASS(ae->ae_f == NULL);
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ae->ae_flags = flags;
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ae->ae_tdp = tdp;
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atomic_interrupt_fence();
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ae->ae_f = f;
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}
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/*
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* XXXKIB Note that the deregistration of an AST handler does not
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* drain threads possibly executing it, which affects unloadable
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* modules. The issue is either handled by the subsystem using
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* handlers, or simply ignored. Fixing the problem is considered not
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* worth the overhead.
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*/
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void
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ast_deregister(int ast)
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{
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struct ast_entry *ae;
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MPASS(ast < TDA_MAX);
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ae = &ast_entries[ast];
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MPASS(ae->ae_f != NULL);
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ae->ae_f = NULL;
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atomic_interrupt_fence();
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ae->ae_flags = 0;
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ae->ae_tdp = 0;
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}
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void
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ast_sched_locked(struct thread *td, int tda)
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{
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THREAD_LOCK_ASSERT(td, MA_OWNED);
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MPASS(tda < TDA_MAX);
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td->td_ast |= TDAI(tda);
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}
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void
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ast_unsched_locked(struct thread *td, int tda)
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{
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THREAD_LOCK_ASSERT(td, MA_OWNED);
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MPASS(tda < TDA_MAX);
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td->td_ast &= ~TDAI(tda);
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}
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void
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ast_sched(struct thread *td, int tda)
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{
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thread_lock(td);
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ast_sched_locked(td, tda);
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thread_unlock(td);
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}
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void
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ast_sched_mask(struct thread *td, int ast)
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{
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thread_lock(td);
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td->td_ast |= ast;
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thread_unlock(td);
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}
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static bool
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ast_handler_calc_tdp_run(struct thread *td, const struct ast_entry *ae)
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{
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return ((ae->ae_flags & ASTR_TDP) == 0 ||
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(td->td_pflags & ae->ae_tdp) != 0);
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}
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/*
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* Process an asynchronous software trap.
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*/
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static void
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ast_handler(struct thread *td, struct trapframe *framep, bool dtor)
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{
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struct ast_entry *ae;
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void (*f)(struct thread *td, int asts);
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int a, td_ast;
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bool run;
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if (framep != NULL) {
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kmsan_mark(framep, sizeof(*framep), KMSAN_STATE_INITED);
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td->td_frame = framep;
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}
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if (__predict_true(!dtor)) {
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WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
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mtx_assert(&Giant, MA_NOTOWNED);
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THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
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/*
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* This updates the td_ast for the checks below in one
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* atomic operation with turning off all scheduled AST's.
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* If another AST is triggered while we are handling the
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* AST's saved in td_ast, the td_ast is again non-zero and
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* ast() will be called again.
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*/
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thread_lock(td);
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td_ast = td->td_ast;
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td->td_ast = 0;
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thread_unlock(td);
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} else {
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/*
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* The td thread's td_lock is not guaranteed to exist,
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* the thread might be not initialized enough when it's
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* destructor is called. It is safe to read and
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* update td_ast without locking since the thread is
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* not runnable or visible to other threads.
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*/
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td_ast = td->td_ast;
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td->td_ast = 0;
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}
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CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, td->td_proc->p_pid,
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td->td_proc->p_comm);
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KASSERT(framep == NULL || TRAPF_USERMODE(framep),
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("ast in kernel mode"));
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for (a = 0; a < nitems(ast_entries); a++) {
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ae = &ast_entries[a];
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f = ae->ae_f;
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if (f == NULL)
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continue;
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atomic_interrupt_fence();
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run = false;
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if (__predict_false(framep == NULL)) {
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if ((ae->ae_flags & ASTR_KCLEAR) != 0)
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run = ast_handler_calc_tdp_run(td, ae);
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} else {
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if ((ae->ae_flags & ASTR_UNCOND) != 0)
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run = true;
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else if ((ae->ae_flags & ASTR_ASTF_REQUIRED) != 0 &&
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(td_ast & TDAI(a)) != 0)
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run = ast_handler_calc_tdp_run(td, ae);
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}
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if (run)
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f(td, td_ast);
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}
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}
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void
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ast(struct trapframe *framep)
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{
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struct thread *td;
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td = curthread;
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ast_handler(td, framep, false);
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userret(td, framep);
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}
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void
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ast_kclear(struct thread *td)
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{
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ast_handler(td, NULL, td != curthread);
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}
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const char *
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syscallname(struct proc *p, u_int code)
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{
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static const char unknown[] = "unknown";
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struct sysentvec *sv;
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sv = p->p_sysent;
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if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
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return (unknown);
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return (sv->sv_syscallnames[code]);
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}
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