pisadep.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	"@(#)Pisadep.c	1.4	04/10/06 SMI"

#include <sys/stack.h>
#include <sys/regset.h>
#include <sys/frame.h>
#include <sys/sysmacros.h>

#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#include <string.h>

#include "Pcontrol.h"
#include "Pstack.h"

#define	M_PLT_NRSV		1	/* reserved PLT entries */
#define	M_PLT_ENTSIZE		16	/* size of each PLT entry */

static uchar_t old_lcall[] = { 0x91, 0, 0, 0, 0, 0x7, 0 };
static uchar_t lcall_instr[] = { 0x9a, 0, 0, 0, 0, 0x27, 0 };

const char *
Ppltdest(struct ps_prochandle *P, uintptr_t pltaddr)
{
	map_info_t *mp = Paddr2mptr(P, pltaddr);

	uintptr_t r_addr;
	file_info_t *fp;
	Elf32_Rel r;
	size_t i;

	if (mp == NULL || (fp = mp->map_file) == NULL ||
	    fp->file_plt_base == 0 ||
	    pltaddr - fp->file_plt_base >= fp->file_plt_size) {
		errno = EINVAL;
		return (NULL);
	}

	i = (pltaddr - fp->file_plt_base) / M_PLT_ENTSIZE - M_PLT_NRSV;

	r_addr = fp->file_jmp_rel + i * sizeof (r);

	if (Pread(P, &r, sizeof (r), r_addr) == sizeof (r) &&
	    (i = ELF32_R_SYM(r.r_info)) < fp->file_dynsym.sym_symn) {

		Elf_Data *data = fp->file_dynsym.sym_data;
		Elf32_Sym *symp = &(((Elf32_Sym *)data->d_buf)[i]);

		return (fp->file_dynsym.sym_strs + symp->st_name);
	}

	return (NULL);
}

int
Pissyscall(struct ps_prochandle *P, uintptr_t addr)
{
	uchar_t instr[16];

	if (Pread(P, instr, sizeof (lcall_instr), addr) !=
	    sizeof (lcall_instr))
		return (0);

	if (memcmp(instr, old_lcall, sizeof (old_lcall)) == 0)
		return (2);
	if (memcmp(instr, lcall_instr, sizeof (lcall_instr)) == 0)
		return (1);

	return (0);
}

int
Pissyscall_prev(struct ps_prochandle *P, uintptr_t addr, uintptr_t *dst)
{
	int ret;

	if (ret = Pissyscall(P, addr - sizeof (lcall_instr))) {
		if (dst)
			*dst = addr - sizeof (lcall_instr);
		return (ret);
	}

	return (0);
}

/* ARGSUSED */
int
Pissyscall_text(struct ps_prochandle *P, const void *buf, size_t buflen)
{
	if (buflen < sizeof (lcall_instr))
		return (0);

	if (memcmp(buf, old_lcall, sizeof (old_lcall)) == 0)
		return (2);
	if (memcmp(buf, lcall_instr, sizeof (lcall_instr)) == 0)
		return (1);

	return (0);
}

#define	TR_ARG_MAX 6	/* Max args to print, same as SPARC */

/*
 * Given a return address, determine the likely number of arguments
 * that were pushed on the stack prior to its execution.  We do this by
 * expecting that a typical call sequence consists of pushing arguments on
 * the stack, executing a call instruction, and then performing an add
 * on %esp to restore it to the value prior to pushing the arguments for
 * the call.  We attempt to detect such an add, and divide the addend
 * by the size of a word to determine the number of pushed arguments.
 *
 * If we do not find such an add, this does not necessarily imply that the
 * function took no arguments. It is not possible to reliably detect such a
 * void function because hand-coded assembler does not always perform an add
 * to %esp immediately after the "call" instruction (eg. _sys_call()).
 * Because of this, we default to returning MIN(sz, TR_ARG_MAX) instead of 0
 * in the absence of an add to %esp.
 */
static ulong_t
argcount(struct ps_prochandle *P, long pc, ssize_t sz)
{
	uchar_t instr[6];
	ulong_t count, max;

	max = MIN(sz / sizeof (long), TR_ARG_MAX);

	/*
	 * Read the instruction at the return location.
	 */
	if (Pread(P, instr, sizeof (instr), pc) != sizeof (instr) ||
	    instr[1] != 0xc4)
		return (max);

	switch (instr[0]) {
	case 0x81:	/* count is a longword */
		count = instr[2]+(instr[3]<<8)+(instr[4]<<16)+(instr[5]<<24);
		break;
	case 0x83:	/* count is a byte */
		count = instr[2];
		break;
	default:
		return (max);
	}

	count /= sizeof (long);
	return (MIN(count, max));
}

static void
ucontext_n_to_prgregs(const ucontext_t *src, prgregset_t dst)
{
	(void) memcpy(dst, src->uc_mcontext.gregs, sizeof (gregset_t));
}

int
Pstack_iter(struct ps_prochandle *P, const prgregset_t regs,
	proc_stack_f *func, void *arg)
{
	prgreg_t *prevfp = NULL;
	uint_t pfpsize = 0;
	int nfp = 0;
	struct {
		long	fp;
		long	pc;
		long	args[32];
	} frame;
	uint_t argc;
	ssize_t sz;
	prgregset_t gregs;
	prgreg_t fp, pfp;
	prgreg_t pc;
	int rv;

	/*
	 * Type definition for a structure corresponding to an IA32
	 * signal frame.  Refer to the comments in Pstack.c for more info
	 */
	typedef struct {
		long fp;
		long pc;
		int signo;
		ucontext_t *ucp;
		siginfo_t *sip;
	} sf_t;

	uclist_t ucl;
	ucontext_t uc;
	uintptr_t uc_addr;

	init_uclist(&ucl, P);
	(void) memcpy(gregs, regs, sizeof (gregs));

	fp = regs[R_FP];
	pc = regs[R_PC];

	while (fp != 0 || pc != 0) {
		if (stack_loop(fp, &prevfp, &nfp, &pfpsize))
			break;

		if (fp != 0 &&
		    (sz = Pread(P, &frame, sizeof (frame), (uintptr_t)fp)
		    >= (ssize_t)(2* sizeof (long)))) {
			/*
			 * One more trick for signal frames: the kernel sets
			 * the return pc of the signal frame to 0xffffffff on
			 * Intel IA32, so argcount won't work.
			 */
			if (frame.pc != -1L) {
				sz -= 2* sizeof (long);
				argc = argcount(P, (long)frame.pc, sz);
			} else
				argc = 3; /* sighandler(signo, sip, ucp) */
		} else {
			(void) memset(&frame, 0, sizeof (frame));
			argc = 0;
		}

		gregs[R_FP] = fp;
		gregs[R_PC] = pc;

		if ((rv = func(arg, gregs, argc, frame.args)) != 0)
			break;

		/*
		 * In order to allow iteration over java frames (which can have
		 * their own frame pointers), we allow the iterator to change
		 * the contents of gregs.  If we detect a change, then we assume
		 * that the new values point to the next frame.
		 */
		if (gregs[R_FP] != fp || gregs[R_PC] != pc) {
			fp = gregs[R_FP];
			pc = gregs[R_PC];
			continue;
		}

		pfp = fp;
		fp = frame.fp;
		pc = frame.pc;

		if (find_uclink(&ucl, pfp + sizeof (sf_t)))
			uc_addr = pfp + sizeof (sf_t);
		else
			uc_addr = NULL;

		if (uc_addr != NULL &&
		    Pread(P, &uc, sizeof (uc), uc_addr) == sizeof (uc)) {

			ucontext_n_to_prgregs(&uc, gregs);
			fp = gregs[R_FP];
			pc = gregs[R_PC];
		}
	}

	if (prevfp)
		free(prevfp);

	free_uclist(&ucl);
	return (rv);
}

uintptr_t
Psyscall_setup(struct ps_prochandle *P, int nargs, int sysindex, uintptr_t sp)
{
	sp -= sizeof (int) * (nargs+2);	/* space for arg list + CALL parms */

	P->status.pr_lwp.pr_reg[EAX] = sysindex;
	P->status.pr_lwp.pr_reg[R_SP] = sp;
	P->status.pr_lwp.pr_reg[R_PC] = P->sysaddr;

	return (sp);
}

int
Psyscall_copyinargs(struct ps_prochandle *P, int nargs, argdes_t *argp,
    uintptr_t ap)
{
	int32_t arglist[MAXARGS+2];
	int i;
	argdes_t *adp;

	for (i = 0, adp = argp; i < nargs; i++, adp++)
		arglist[1 + i] = (int32_t)adp->arg_value;

	arglist[0] = P->status.pr_lwp.pr_reg[R_PC];
	if (Pwrite(P, &arglist[0], sizeof (int) * (nargs+1),
	    (uintptr_t)ap) != sizeof (int) * (nargs+1))
		return (-1);

	return (0);
}

int
Psyscall_copyoutargs(struct ps_prochandle *P, int nargs, argdes_t *argp,
    uintptr_t ap)
{
	uint32_t arglist[MAXARGS + 2];
	int i;
	argdes_t *adp;

	if (Pread(P, &arglist[0], sizeof (int) * (nargs+1), (uintptr_t)ap)
	    != sizeof (int) * (nargs+1))
		return (-1);

	for (i = 0, adp = argp; i < nargs; i++, adp++)
		adp->arg_value = arglist[i];

	return (0);
}