dtrace_subr.c

Sun Solaris 10 中的 DTrace 组件的源代码。请参看: http://www.sun.com/software/solaris/observability.jsp

/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only.
 * See the file usr/src/LICENSING.NOTICE in this distribution or
 * http://www.opensolaris.org/license/ for details.
 */

#pragma ident	"@(#)dtrace_subr.c	1.5	04/04/06 SMI"

#include <sys/dtrace.h>
#include <sys/fasttrap.h>
#include <sys/x_call.h>
#include <sys/atomic.h>
#include <sys/machsystm.h>

static void
dtrace_xcall_func(uint64_t arg1, uint64_t arg2)
{
	(*(dtrace_xcall_t)arg1)((void *)(arg2));
}

void
dtrace_xcall(processorid_t cpu, dtrace_xcall_t func, void *arg)
{
	if (cpu == DTRACE_CPUALL) {
		xc_all(dtrace_xcall_func, (uint64_t)func, (uint64_t)arg);
	} else {
		xc_one(cpu, dtrace_xcall_func, (uint64_t)func, (uint64_t)arg);
	}
}

/*ARGSUSED*/
static void
dtrace_sync_func(uint64_t arg1, uint64_t arg2)
{
	membar_consumer();
}

void
dtrace_sync(void)
{
	membar_producer();
	xc_all(dtrace_sync_func, 0, 0);
}

void
dtrace_toxic_ranges(void (*func)(uintptr_t base, uintptr_t limit))
{
	(*func)(PIOMAPBASE, PIOMAPBASE + PIOMAPSIZE);
	(*func)(OFW_START_ADDR, OFW_END_ADDR);

	if (hole_end > hole_start)
		(*func)((uintptr_t)hole_start, (uintptr_t)hole_end);
}

int (*dtrace_fasttrap_probe_ptr)(struct regs *);

void
dtrace_fasttrap_probe(struct regs *rp)
{
	krwlock_t *rwp = &CPU->cpu_ft_lock;

	rw_enter(rwp, RW_READER);
	if (dtrace_fasttrap_probe_ptr == NULL) {
		rw_exit(rwp);
		rp->r_pc = rp->r_npc;
		rp->r_npc = rp->r_pc + 4;
	} else {
		(void) (*dtrace_fasttrap_probe_ptr)(rp);
		rw_exit(rwp);
	}
}

int (*dtrace_pid_probe_ptr)(struct regs *);

void
dtrace_pid_probe(struct regs *rp)
{
	krwlock_t *rwp = &CPU->cpu_ft_lock;
	uint32_t instr;

	/*
	 * This trap should only be invoked if there's a corresponding
	 * enabled dtrace probe. If there isn't, send SIGILL as though
	 * the process had executed an invalid trap instruction.
	 */
	rw_enter(rwp, RW_READER);
	if (dtrace_pid_probe_ptr != NULL && (*dtrace_pid_probe_ptr)(rp) == 0) {
		rw_exit(rwp);
		return;
	}
	rw_exit(rwp);

	/*
	 * It is possible that we were preempted after entering the kernel,
	 * and the tracepoint was removed. If it appears that the process hit
	 * our reserved trap instruction, we call send SIGILL just as though
	 * the user had executed an unused trap instruction.
	 */
	if (fuword32((void *)rp->r_pc, &instr) != 0 ||
	    instr == FASTTRAP_INSTR) {
		sigqueue_t *sqp = kmem_zalloc(sizeof (sigqueue_t), KM_SLEEP);
		proc_t *p = curproc;

		sqp->sq_info.si_signo = SIGILL;
		sqp->sq_info.si_code = ILL_ILLTRP;
		sqp->sq_info.si_addr = (caddr_t)rp->r_pc;
		sqp->sq_info.si_trapno = 0x38;

		mutex_enter(&p->p_lock);
		sigaddqa(p, curthread, sqp);
		mutex_exit(&p->p_lock);
		aston(curthread);
	}
}

int (*dtrace_return_probe_ptr)(struct regs *);

void
dtrace_return_probe(struct regs *rp)
{
	krwlock_t *rwp;
	uintptr_t npc = curthread->t_dtrace_npc;
	uint8_t on = curthread->t_dtrace_on;
	uint8_t step = curthread->t_dtrace_step;
	uint8_t ret = curthread->t_dtrace_ret;

	if (curthread->t_dtrace_ast) {
		aston(curthread);
		curthread->t_sig_check = 1;
	}

	/*
	 * Clear all user tracing flags.
	 */
	curthread->t_dtrace_ft = 0;

	/*
	 * If we weren't expecting to take a return probe trap, kill the
	 * process as though it had just executed an unassigned trap
	 * instruction.
	 */
	if (step == 0) {
		ASSERT(on != 0);
		tsignal(curthread, SIGILL);
		return;
	}

	ASSERT(rp->r_npc == rp->r_pc + 4);

	/*
	 * If we hit this trap unrelated to a return probe, we're just here
	 * to reset the AST flag since we deferred a signal until after we
	 * logically single-stepped the instruction we copied out.
	 */
	if (ret == 0) {
		rp->r_pc = npc;
		rp->r_npc = npc + 4;
		return;
	}

	/*
	 * We need to wait until after we've called the dtrace_return_probe_ptr
	 * function pointer to set %pc and %npc.
	 */
	rwp = &CPU->cpu_ft_lock;
	rw_enter(rwp, RW_READER);
	if (dtrace_return_probe_ptr != NULL)
		(void) (*dtrace_return_probe_ptr)(rp);
	rw_exit(rwp);
	rp->r_pc = npc;
	rp->r_npc = npc + 4;
}

void
dtrace_safe_synchronous_signal(void)
{
	kthread_t *t = curthread;
	struct regs *rp = lwptoregs(ttolwp(t));

	ASSERT(t->t_dtrace_on);

	/*
	 * If we're not actively tracing an instruction, turn off tracing
	 * flags. If the instruction we copied out caused a synchronous
	 * trap, reset the pc and npc back to their original values and turn
	 * off the flags.
	 */
	if (rp->r_pc != t->t_dtrace_scrpc && rp->r_pc != t->t_dtrace_astpc &&
	    rp->r_npc != t->t_dtrace_astpc) {
		t->t_dtrace_ft = 0;
	} else if (rp->r_pc == t->t_dtrace_scrpc) {
		rp->r_pc = t->t_dtrace_pc;
		rp->r_npc = t->t_dtrace_npc;
		t->t_dtrace_ft = 0;
	}
}

int
dtrace_safe_defer_signal(void)
{
	kthread_t *t = curthread;
	struct regs *rp = lwptoregs(ttolwp(t));

	ASSERT(t->t_dtrace_on);

	/*
	 * If we're not actively tracing an instruction, turn off tracing
	 * flags.
	 */
	if (rp->r_pc != t->t_dtrace_scrpc && rp->r_pc != t->t_dtrace_astpc &&
	    rp->r_npc != t->t_dtrace_astpc) {
		t->t_dtrace_ft = 0;
		return (0);
	}

	/*
	 * Otherwise, make sure we'll return to the kernel after executing
	 * the instruction we copied out.
	 */
	if (!t->t_dtrace_step) {
		ASSERT(rp->r_pc == t->t_dtrace_scrpc);
		rp->r_npc = t->t_dtrace_astpc;
		t->t_dtrace_step = 1;
	}

	t->t_dtrace_ast = 1;

	return (1);
}