dtrace_isa.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_isa.c	1.6	04/11/17 SMI"

#include <sys/dtrace_impl.h>
#include <sys/atomic.h>
#include <sys/model.h>
#include <sys/frame.h>
#include <sys/stack.h>
#include <sys/machpcb.h>
#include <sys/procfs_isa.h>
#include <sys/cmn_err.h>

#define	DTRACE_FMT3OP3_MASK	0x81000000
#define	DTRACE_FMT3OP3		0x80000000
#define	DTRACE_FMT3RS1_SHIFT	14
#define	DTRACE_FMT3RD_SHIFT	25
#define	DTRACE_RMASK		0x1f
#define	DTRACE_REG_L0		16
#define	DTRACE_REG_O7		15
#define	DTRACE_REG_I0		24
#define	DTRACE_REG_I6		30
#define	DTRACE_RET		0x81c7e008
#define	DTRACE_RETL		0x81c3e008
#define	DTRACE_SAVE_MASK	0xc1f80000
#define	DTRACE_SAVE		0x81e00000
#define	DTRACE_RESTORE		0x81e80000
#define	DTRACE_CALL_MASK	0x40000000
#define	DTRACE_JMPL_MASK	0x81f10000
#define	DTRACE_JMPL		0x81c00000

extern int dtrace_getupcstack_top(uint64_t *, int, uintptr_t *);
extern ulong_t dtrace_getreg_win(uint_t, uint_t);
extern void dtrace_putreg_win(uint_t, ulong_t);
extern int dtrace_fish(int, int, uintptr_t *);

/*
 * This is similar in principle to getpcstack(), but there are several marked
 * differences in implementation:
 *
 * (a)	dtrace_getpcstack() is called from probe context.  Thus, the call
 *	to flush_windows() from getpcstack() is a call to the probe-safe
 *	equivalent here.
 *
 * (b)  dtrace_getpcstack() is willing to sacrifice some performance to get
 *	a correct stack.  While consumers of getpcstack() are largely
 *	subsystem-specific in-kernel debugging facilities, DTrace consumers
 *	are arbitrary user-level analysis tools; dtrace_getpcstack() must
 *	deliver as correct a stack as possible.  Details on the issues
 *	surrounding stack correctness are found below.
 *
 * (c)	dtrace_getpcstack() _always_ fills in pstack_limit pc_t's -- filling
 *	in the difference between the stack depth and pstack_limit with NULLs.
 *	Due to this behavior dtrace_getpcstack() returns void.
 *
 * (d)	dtrace_getpcstack() takes a third parameter, aframes, that
 *	denotes the number of _artificial frames_ on the bottom of the
 *	stack.  An artificial frame is one induced by the provider; all
 *	artificial frames are stripped off before frames are stored to
 *	pcstack.
 *
 * (e)	dtrace_getpcstack() takes a fourth parameter, pc, that indicates
 *	an interrupted program counter (if any).  This should be a non-NULL
 *	value if and only if the hit probe is unanchored.  (Anchored probes
 *	don't fire through an interrupt source.)  This parameter is used to
 *	assure (b), above.
 */
void
dtrace_getpcstack(pc_t *pcstack, int pcstack_limit, int aframes, uint32_t *pc)
{
	struct frame *fp, *nextfp, *minfp, *stacktop;
	int depth = 0;
	int on_intr, j = 0;
	uint32_t i, r;

	fp = (struct frame *)((caddr_t)dtrace_getfp() + STACK_BIAS);
	dtrace_flush_windows();

	if (pc != NULL) {
		/*
		 * If we've been passed a non-NULL pc, we need to determine
		 * whether or not the specified program counter falls in a leaf
		 * function.  If it falls within a leaf function, we know that
		 * %o7 is valid in its frame (and we can just drive on).  If
		 * it's a non-leaf, however, we know that %o7 is garbage in the
		 * bottom frame.  To trim this frame, we simply increment
		 * aframes and drop into the stack-walking loop.
		 *
		 * To quickly determine if the specified program counter is in
		 * a leaf function, we exploit the fact that leaf functions
		 * tend to be short and non-leaf functions tend to frequently
		 * perform operations that are only permitted in a non-leaf
		 * function (e.g., using the %i's or %l's; calling a function;
		 * performing a restore).  We exploit these tendencies by
		 * simply scanning forward from the specified %pc -- if we see
		 * an operation only permitted in a non-leaf, we know we're in
		 * a non-leaf; if we see a retl, we know we're in a leaf.
		 * Fortunately, one need not perform anywhere near full
		 * disassembly to effectively determine the former: determining
		 * that an instruction is a format-3 instruction and decoding
		 * its rd and rs1 fields, for example, requires very little
		 * manipulation.  Overall, this method of leaf determination
		 * performs quite well:  on average, we only examine between
		 * 1.5 and 2.5 instructions before making the determination.
		 * (Outliers do exist, however; of note is the non-leaf
		 * function ip_sioctl_not_ours() which -- as of this writing --
		 * has a whopping 455 straight instructions that manipulate
		 * only %g's and %o's.)
		 */
		int delay = 0;

		for (;;) {
			i = pc[j++];

			if ((i & DTRACE_FMT3OP3_MASK) == DTRACE_FMT3OP3) {
				/*
				 * This is a format-3 instruction.  We can
				 * look at rd and rs1.
				 */
				r = (i >> DTRACE_FMT3RS1_SHIFT) & DTRACE_RMASK;

				if (r >= DTRACE_REG_L0)
					goto nonleaf;

				r = (i >> DTRACE_FMT3RD_SHIFT) & DTRACE_RMASK;

				if (r >= DTRACE_REG_L0)
					goto nonleaf;

				if ((i & DTRACE_JMPL_MASK) == DTRACE_JMPL) {
					delay = 1;
					continue;
				}

				/*
				 * If we see explicit manipulation with %o7
				 * as a destination register, we know that
				 * %o7 is likely bogus -- and we treat this
				 * function as a non-leaf.
				 */
				if (r == DTRACE_REG_O7) {
					if (delay)
						goto leaf;

					i &= DTRACE_JMPL_MASK;

					if (i == DTRACE_JMPL) {
						delay = 1;
						continue;
					}

					goto nonleaf;
				}
			} else {
				/*
				 * If this is a call, it may or may not be
				 * a leaf; we need to check the delay slot.
				 */
				if ((i & DTRACE_CALL_MASK) ==
				    DTRACE_CALL_MASK) {
					delay = 1;
					continue;
				}

				/*
				 * If we see a ret it's not a leaf; if we
				 * see a retl, it is a leaf.
				 */
				if (i == DTRACE_RET)
					goto nonleaf;

				if (i == DTRACE_RETL)
					goto leaf;

				/*
				 * Finally, if it's a save, it should be
				 * treated as a leaf; if it's a restore it
				 * should not be treated as a leaf.
				 */
				if ((i & DTRACE_SAVE_MASK) == DTRACE_SAVE)
					goto leaf;

				if ((i & DTRACE_SAVE_MASK) == DTRACE_RESTORE)
					goto nonleaf;
			}

			if (delay) {
				/*
				 * If this was a delay slot instruction and
				 * we didn't pick it up elsewhere, this is a
				 * non-leaf.
				 */
				goto nonleaf;
			}
		}
nonleaf:
		aframes++;
leaf:
		;
	}

	if ((on_intr = CPU_ON_INTR(CPU)) != 0)
		stacktop = (struct frame *)(CPU->cpu_intr_stack + SA(MINFRAME));
	else
		stacktop = (struct frame *)curthread->t_stk;
	minfp = fp;

	while (depth < pcstack_limit) {
		nextfp = (struct frame *)((caddr_t)fp->fr_savfp + STACK_BIAS);
		if (nextfp <= minfp || nextfp >= stacktop) {
			if (!on_intr && nextfp == stacktop && aframes != 0) {
				/*
				 * If we are exactly at the top of the stack
				 * with a non-zero number of artificial frames,
				 * it must be that the stack is filled with
				 * nothing _but_ artificial frames.  In this
				 * case, we assert that this is so, zero
				 * pcstack, and return.
				 */
				ASSERT(aframes == 1);
				ASSERT(depth == 0);

				while (depth < pcstack_limit)
					pcstack[depth++] = NULL;
				return;
			}

			if (on_intr) {
				/*
				 * Hop from interrupt stack to thread stack.
				 */
				stacktop = (struct frame *)curthread->t_stk;
				minfp = (struct frame *)curthread->t_stkbase;

				on_intr = 0;

				if (nextfp > minfp && nextfp < stacktop)
					continue;
			} else {
				/*
				 * High-level interrupts may occur when %sp is
				 * not necessarily contained in the stack
				 * bounds implied by %g7 -- interrupt thread
				 * management runs with %pil at DISP_LEVEL,
				 * and high-level interrupts may thus occur
				 * in windows when %sp and %g7 are not self-
				 * consistent.  If we call dtrace_getpcstack()
				 * from a high-level interrupt that has occurred
				 * in such a window, we will fail the above test
				 * of nextfp against minfp/stacktop.  If the
				 * high-level interrupt has in turn interrupted
				 * a non-passivated interrupt thread, we
				 * will execute the below code with non-zero
				 * aframes.  We therefore want to assert that
				 * aframes is zero _or_ we are in a high-level
				 * interrupt -- but because cpu_intr_actv is
				 * updated with high-level interrupts enabled,
				 * we must reduce this to only asserting that
				 * %pil is greater than DISP_LEVEL.
				 */
				ASSERT(aframes == 0 ||
				    dtrace_getipl() > DISP_LEVEL);
				pcstack[depth++] = (pc_t)fp->fr_savpc;
			}

			while (depth < pcstack_limit)
				pcstack[depth++] = NULL;
			return;
		}

		if (aframes > 0) {
			aframes--;
		} else {
			pcstack[depth++] = (pc_t)fp->fr_savpc;
		}

		fp = nextfp;
		minfp = fp;
	}
}

void
dtrace_getupcstack(uint64_t *pcstack, int pcstack_limit)
{
	klwp_t *lwp = ttolwp(curthread);
	proc_t *p = ttoproc(curthread);
	struct regs *rp;
	uintptr_t sp;
	int n;

	if (lwp == NULL || p == NULL || lwp->lwp_regs == NULL)
		return;

	if (pcstack_limit <= 0)
		return;

	*pcstack++ = (uint64_t)p->p_pid;
	pcstack_limit--;

	if (pcstack_limit <= 0)
		return;

	rp = lwp->lwp_regs;
	*pcstack++ = (uint64_t)rp->r_pc;
	pcstack_limit--;

	if (pcstack_limit <= 0)
		return;

	if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_ENTRY)) {
		*pcstack++ = (uint64_t)rp->r_o7;
		pcstack_limit--;
		if (pcstack_limit <= 0)
			return;
	}

	sp = rp->r_sp;

	n = dtrace_getupcstack_top(pcstack, pcstack_limit, &sp);
	ASSERT(n >= 0);
	ASSERT(n <= pcstack_limit);

	pcstack += n;
	pcstack_limit -= n;

	if (p->p_model == DATAMODEL_NATIVE) {
		while (pcstack_limit > 0) {
			struct frame *fr = (struct frame *)(sp + STACK_BIAS);
			uintptr_t pc;

			if (sp == 0 || fr == NULL ||
			    ((uintptr_t)&fr->fr_savpc & 3) != 0 ||
			    ((uintptr_t)&fr->fr_savfp & 3) != 0)
				break;

			pc = dtrace_fulword(&fr->fr_savpc);
			sp = dtrace_fulword(&fr->fr_savfp);

			if (pc == 0)
				break;

			*pcstack++ = pc;
			pcstack_limit--;
		}
	} else {
		while (pcstack_limit > 0) {
			struct frame32 *fr = (struct frame32 *)sp;
			uint32_t pc;

			if (sp == 0 ||
			    ((uintptr_t)&fr->fr_savpc & 3) != 0 ||
			    ((uintptr_t)&fr->fr_savfp & 3) != 0)
				break;

			pc = dtrace_fuword32(&fr->fr_savpc);
			sp = dtrace_fuword32(&fr->fr_savfp);

			*pcstack++ = pc;
			pcstack_limit--;
		}
	}

	while (pcstack_limit-- > 0)
		*pcstack++ = NULL;
}

void
dtrace_getufpstack(uint64_t *pcstack, uint64_t *fpstack, int pcstack_limit)
{
	klwp_t *lwp = ttolwp(curthread);
	proc_t *p = ttoproc(curthread);
	struct regs *rp;
	uintptr_t sp;