intel/mdb/mdb_amd64util.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <sys/types.h>
#include <sys/reg.h>
#include <sys/privregs.h>
#include <sys/stack.h>
#include <sys/frame.h>

#include <mdb/mdb_target_impl.h>
#include <mdb/mdb_kreg_impl.h>
#include <mdb/mdb_debug.h>
#include <mdb/mdb_modapi.h>
#include <mdb/mdb_amd64util.h>
#include <mdb/mdb_ctf.h>
#include <mdb/mdb_err.h>
#include <mdb/mdb.h>

/*
 * This array is used by the getareg and putareg entry points, and also by our
 * register variable discipline.
 */

const mdb_tgt_regdesc_t mdb_amd64_kregs[] = {
	{ "savfp", KREG_SAVFP, MDB_TGT_R_EXPORT },
	{ "savpc", KREG_SAVPC, MDB_TGT_R_EXPORT },
	{ "rdi", KREG_RDI, MDB_TGT_R_EXPORT },
	{ "rsi", KREG_RSI, MDB_TGT_R_EXPORT },
	{ "rdx", KREG_RDX, MDB_TGT_R_EXPORT },
	{ "rcx", KREG_RCX, MDB_TGT_R_EXPORT },
	{ "r8", KREG_R8, MDB_TGT_R_EXPORT },
	{ "r9", KREG_R9, MDB_TGT_R_EXPORT },
	{ "rax", KREG_RAX, MDB_TGT_R_EXPORT },
	{ "rbx", KREG_RBX, MDB_TGT_R_EXPORT },
	{ "rbp", KREG_RBP, MDB_TGT_R_EXPORT },
	{ "r10", KREG_R10, MDB_TGT_R_EXPORT },
	{ "r11", KREG_R11, MDB_TGT_R_EXPORT },
	{ "r12", KREG_R12, MDB_TGT_R_EXPORT },
	{ "r13", KREG_R13, MDB_TGT_R_EXPORT },
	{ "r14", KREG_R14, MDB_TGT_R_EXPORT },
	{ "r15", KREG_R15, MDB_TGT_R_EXPORT },
	{ "ds", KREG_DS, MDB_TGT_R_EXPORT },
	{ "es", KREG_ES, MDB_TGT_R_EXPORT },
	{ "fs", KREG_FS, MDB_TGT_R_EXPORT },
	{ "gs", KREG_GS, MDB_TGT_R_EXPORT },
	{ "trapno", KREG_TRAPNO, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV },
	{ "err", KREG_ERR, MDB_TGT_R_EXPORT | MDB_TGT_R_PRIV },
	{ "rip", KREG_RIP, MDB_TGT_R_EXPORT },
	{ "cs", KREG_CS, MDB_TGT_R_EXPORT },
	{ "rflags", KREG_RFLAGS, MDB_TGT_R_EXPORT },
	{ "rsp", KREG_RSP, MDB_TGT_R_EXPORT },
	{ "ss", KREG_SS, MDB_TGT_R_EXPORT },
	{ NULL, 0, 0 }
};

void
mdb_amd64_printregs(const mdb_tgt_gregset_t *gregs)
{
	const kreg_t *kregs = &gregs->kregs[0];
	kreg_t rflags = kregs[KREG_RFLAGS];

#define	GETREG2(x) ((uintptr_t)kregs[(x)]), ((uintptr_t)kregs[(x)])

	mdb_printf("%%rax = 0x%0?p %15A %%r9  = 0x%0?p %A\n",
	    GETREG2(KREG_RAX), GETREG2(KREG_R9));
	mdb_printf("%%rbx = 0x%0?p %15A %%r10 = 0x%0?p %A\n",
	    GETREG2(KREG_RBX), GETREG2(KREG_R10));
	mdb_printf("%%rcx = 0x%0?p %15A %%r11 = 0x%0?p %A\n",
	    GETREG2(KREG_RCX), GETREG2(KREG_R11));
	mdb_printf("%%rdx = 0x%0?p %15A %%r12 = 0x%0?p %A\n",
	    GETREG2(KREG_RDX), GETREG2(KREG_R12));
	mdb_printf("%%rsi = 0x%0?p %15A %%r13 = 0x%0?p %A\n",
	    GETREG2(KREG_RSI), GETREG2(KREG_R13));
	mdb_printf("%%rdi = 0x%0?p %15A %%r14 = 0x%0?p %A\n",
	    GETREG2(KREG_RDI), GETREG2(KREG_R14));
	mdb_printf("%%r8  = 0x%0?p %15A %%r15 = 0x%0?p %A\n\n",
	    GETREG2(KREG_R8), GETREG2(KREG_R15));

	mdb_printf("%%rip = 0x%0?p %A\n", GETREG2(KREG_RIP));
	mdb_printf("%%rbp = 0x%0?p\n", kregs[KREG_RBP]);
	mdb_printf("%%rsp = 0x%0?p\n", kregs[KREG_RSP]);

	mdb_printf("%%rflags = 0x%08x\n", rflags);

	mdb_printf("  id=%u vip=%u vif=%u ac=%u vm=%u rf=%u nt=%u iopl=0x%x\n",
	    (rflags & KREG_EFLAGS_ID_MASK) >> KREG_EFLAGS_ID_SHIFT,
	    (rflags & KREG_EFLAGS_VIP_MASK) >> KREG_EFLAGS_VIP_SHIFT,
	    (rflags & KREG_EFLAGS_VIF_MASK) >> KREG_EFLAGS_VIF_SHIFT,
	    (rflags & KREG_EFLAGS_AC_MASK) >> KREG_EFLAGS_AC_SHIFT,
	    (rflags & KREG_EFLAGS_VM_MASK) >> KREG_EFLAGS_VM_SHIFT,
	    (rflags & KREG_EFLAGS_RF_MASK) >> KREG_EFLAGS_RF_SHIFT,
	    (rflags & KREG_EFLAGS_NT_MASK) >> KREG_EFLAGS_NT_SHIFT,
	    (rflags & KREG_EFLAGS_IOPL_MASK) >> KREG_EFLAGS_IOPL_SHIFT);

	mdb_printf("  status=<%s,%s,%s,%s,%s,%s,%s,%s,%s>\n\n",
	    (rflags & KREG_EFLAGS_OF_MASK) ? "OF" : "of",
	    (rflags & KREG_EFLAGS_DF_MASK) ? "DF" : "df",
	    (rflags & KREG_EFLAGS_IF_MASK) ? "IF" : "if",
	    (rflags & KREG_EFLAGS_TF_MASK) ? "TF" : "tf",
	    (rflags & KREG_EFLAGS_SF_MASK) ? "SF" : "sf",
	    (rflags & KREG_EFLAGS_ZF_MASK) ? "ZF" : "zf",
	    (rflags & KREG_EFLAGS_AF_MASK) ? "AF" : "af",
	    (rflags & KREG_EFLAGS_PF_MASK) ? "PF" : "pf",
	    (rflags & KREG_EFLAGS_CF_MASK) ? "CF" : "cf");

	mdb_printf("%24s%%cs = 0x%04x\t%%ds = 0x%04x\t%%es = 0x%04x\n",
	    " ", kregs[KREG_CS], kregs[KREG_DS], kregs[KREG_ES]);

	mdb_printf("%%trapno = 0x%x\t\t%%fs = 0x%04x\t%%gs = 0x%04x\n",
	    kregs[KREG_TRAPNO], (kregs[KREG_FS] & 0xffff),
	    (kregs[KREG_GS] & 0xffff));
	mdb_printf("   %%err = 0x%x\n", kregs[KREG_ERR]);
}

/*
 * Sun Studio 10 patch compiler and gcc 3.4.3 Sun branch implemented a
 * "-save_args" option on amd64.  When the option is specified, INTEGER
 * type function arguments passed via registers will be saved on the stack
 * immediately after %rbp, and will not be modified through out the life
 * of the routine.
 *
 *				+--------+
 *		%rbp	-->     |  %rbp  |
 *				+--------+
 *		-0x8(%rbp)	|  %rdi  |
 *				+--------+
 *		-0x10(%rbp)	|  %rsi  |
 *				+--------+
 *		-0x18(%rbp)	|  %rdx  |
 *				+--------+
 *		-0x20(%rbp)	|  %rcx  |
 *				+--------+
 *		-0x28(%rbp)	|  %r8   |
 *				+--------+
 *		-0x30(%rbp)	|  %r9   |
 *				+--------+
 *
 *
 * For example, for the following function,
 *
 * void
 * foo(int a1, int a2, int a3, int a4, int a5, int a6, int a7)
 * {
 * ...
 * }
 *
 * Disassembled code will look something like the following:
 *
 *     pushq	%rbp
 *     movq	%rsp, %rbp
 *     subq	$imm8, %rsp			**
 *     movq	%rdi, -0x8(%rbp)
 *     movq	%rsi, -0x10(%rbp)
 *     movq	%rdx, -0x18(%rbp)
 *     movq	%rcx, -0x20(%rbp)
 *     movq	%r8, -0x28(%rbp)
 *     movq	%r9, -0x30(%rbp)
 *     ...
 * or
 *     pushq	%rbp
 *     movq	%rsp, %rbp
 *     subq	$imm8, %rsp			**
 *     movq	%r9, -0x30(%rbp)
 *     movq	%r8, -0x28(%rbp)
 *     movq	%rcx, -0x20(%rbp)
 *     movq	%rdx, -0x18(%rbp)
 *     movq	%rsi, -0x10(%rbp)
 *     movq	%rdi, -0x8(%rbp)
 *     ...
 *
 * **: The space being reserved is in addition to what the current
 *     function prolog already reserves.
 *
 * If there are odd number of arguments to a function, additional space is
 * reserved on the stack to maintain 16-byte alignment.  For example,
 *
 *     argc == 0: no argument saving.
 *     argc == 3: save 3, but space for 4 is reserved
 *     argc == 7: save 6.
 */

/*
 * The longest instruction sequence in bytes before all 6 arguments are
 * saved on the stack.  This value depends on compiler implementation,
 * therefore it should be examined periodically to guarantee accuracy.
 */
#define	SEQ_LEN		80

/*
 * Size of the instruction sequence arrays.  It should correspond to
 * the maximum number of arguments passed via registers.
 */
#define	INSTR_ARRAY_SIZE	6

#define	INSTR4(ins, off)	\
	(ins[(off)] + (ins[(off) + 1] << 8) + (ins[(off + 2)] << 16) + \
	(ins[(off) + 3] << 24))

/*
 * Sun Studio 10 patch implementation saves %rdi first;
 * GCC 3.4.3 Sun branch implementation saves them in reverse order.
 */
static const uint32_t save_instr[INSTR_ARRAY_SIZE] = {
	0xf87d8948,	/* movq %rdi, -0x8(%rbp) */
	0xf0758948,	/* movq %rsi, -0x10(%rbp) */
	0xe8558948,	/* movq %rdx, -0x18(%rbp) */
	0xe04d8948,	/* movq %rcx, -0x20(%rbp) */
	0xd845894c,	/* movq %r8, -0x28(%rbp) */
	0xd04d894c	/* movq %r9, -0x30(%rbp) */
};

static const uint32_t save_fp_instr[] = {
	0xe5894855,	/* pushq %rbp; movq %rsp,%rbp, encoding 1 */
	0xec8b4855,	/* pushq %rbp; movq %rsp,%rbp, encoding 2 */
	0xe58948cc,	/* int $0x3; movq %rsp,%rbp, encoding 1 */
	0xec8b48cc,	/* int $0x3; movq %rsp,%rbp, encoding 2 */
	NULL
};

/*
 * Look for the above instruction sequences as indicators for register
 * arguments being available on the stack.
 */
static int
is_argsaved(mdb_tgt_t *t, uintptr_t fstart, uint64_t size, uint_t argc,
    int start_index)
{
	uint8_t		ins[SEQ_LEN];
	int		i, j;
	uint32_t	n;

	size = MIN(size, SEQ_LEN);
	argc = MIN((start_index + argc), INSTR_ARRAY_SIZE);

	if (mdb_tgt_vread(t, ins, size, fstart) != size)
		return (0);

	/*
	 * Make sure framepointer has been saved.
	 */
	n = INSTR4(ins, 0);
	for (i = 0; save_fp_instr[i] != NULL; i++) {
		if (n == save_fp_instr[i])
			break;
	}

	if (save_fp_instr[i] == NULL)
		return (0);

	/*
	 * Compare against Sun Studio implementation
	 */
	for (i = 8, j = start_index; i < size - 4; i++) {
		n = INSTR4(ins, i);

		if (n == save_instr[j]) {
			i += 3;
			if (++j >= argc)
				return (1);
		}
	}

	/*
	 * Compare against GCC implementation
	 */
	for (i = 8, j = argc - 1; i < size - 4; i++) {
		n = INSTR4(ins, i);

		if (n == save_instr[j]) {
			i += 3;
			if (--j < start_index)
				return (1);
		}
	}

	return (0);
}

/*
 * We expect all proper Solaris core files to have STACK_ALIGN-aligned stacks.
 * Hence the name.  However, if the core file resulted from a
 * hypervisor-initiated panic, the hypervisor's frames may only be 64-bit
 * aligned instead of 128.
 */
static int
fp_is_aligned(uintptr_t fp, int xpv_panic)
{
	if (!xpv_panic && (fp & (STACK_ALIGN -1)))
		return (0);
	if ((fp & sizeof (uintptr_t) - 1))
		return (0);
	return (1);
}

int
mdb_amd64_kvm_stack_iter(mdb_tgt_t *t, const mdb_tgt_gregset_t *gsp,
    mdb_tgt_stack_f *func, void *arg)
{
	mdb_tgt_gregset_t gregs;
	kreg_t *kregs = &gregs.kregs[0];
	int got_pc = (gsp->kregs[KREG_RIP] != 0);
	uint_t argc, reg_argc;
	long fr_argv[32];
	int start_index; /* index to save_instr where to start comparison */
	int i;

	struct {
		uintptr_t fr_savfp;
		uintptr_t fr_savpc;
	} fr;

	uintptr_t fp = gsp->kregs[KREG_RBP];
	uintptr_t pc = gsp->kregs[KREG_RIP];
	uintptr_t lastfp, curpc;

	ssize_t size;

	GElf_Sym s;
	mdb_syminfo_t sip;
	mdb_ctf_funcinfo_t mfp;
	int xpv_panic = 0;
#ifndef	_KMDB
	int xp;

	if ((mdb_readsym(&xp, sizeof (xp), "xpv_panicking") != -1) && (xp > 0))
		xpv_panic = 1;
#endif

	bcopy(gsp, &gregs, sizeof (gregs));

	while (fp != 0) {

		curpc = pc;

		if (!fp_is_aligned(fp, xpv_panic))
			return (set_errno(EMDB_STKALIGN));

		if (mdb_tgt_vread(t, &fr, sizeof (fr), fp) != sizeof (fr))
			return (-1);	/* errno has been set for us */

		if ((mdb_tgt_lookup_by_addr(t, pc, MDB_TGT_SYM_FUZZY,
		    NULL, 0, &s, &sip) == 0) &&
		    (mdb_ctf_func_info(&s, &sip, &mfp) == 0)) {
			int return_type = mdb_ctf_type_kind(mfp.mtf_return);
			argc = mfp.mtf_argc;
			/*
			 * If the function returns a structure or union,
			 * %rdi contains the address in which to store the
			 * return value rather than for an argument.
			 */
			if (return_type == CTF_K_STRUCT ||
			    return_type == CTF_K_UNION)
				start_index = 1;
			else
				start_index = 0;
		} else {
			argc = 0;
		}

		if (argc != 0 && is_argsaved(t, s.st_value, s.st_size,
		    argc, start_index)) {

			/* Upto to 6 arguments are passed via registers */
			reg_argc = MIN(6, mfp.mtf_argc);
			size = reg_argc * sizeof (long);

			if (mdb_tgt_vread(t, fr_argv, size, (fp - size))
			    != size)
				return (-1);	/* errno has been set for us */

			/*
			 * Arrange the arguments in the right order for
			 * printing.
			 */
			for (i = 0; i < (reg_argc >> 1); i++) {
				long t = fr_argv[i];

				fr_argv[i] = fr_argv[reg_argc - i - 1];
				fr_argv[reg_argc - i - 1] = t;
			}

			if (argc > 6) {
				size = (argc - 6) * sizeof (long);
				if (mdb_tgt_vread(t, &fr_argv[6], size,
				    fp + sizeof (fr)) != size)
					return (-1); /* errno has been set */
			}
		} else
			argc = 0;

		if (got_pc && func(arg, pc, argc, fr_argv, &gregs) != 0)
			break;

		kregs[KREG_RSP] = kregs[KREG_RBP];

		lastfp = fp;
		fp = fr.fr_savfp;
		/*
		 * The Xen hypervisor marks a stack frame as belonging to
		 * an exception by inverting the bits of the pointer to
		 * that frame.  We attempt to identify these frames by
		 * inverting the pointer and seeing if it is within 0xfff
		 * bytes of the last frame.
		 */
		if (xpv_panic)
			if ((fp != 0) && (fp < lastfp) &&
			    ((lastfp ^ ~fp) < 0xfff))
			fp = ~fp;

		kregs[KREG_RBP] = fp;
		kregs[KREG_RIP] = pc = fr.fr_savpc;

		if (curpc == pc)
			break;

		got_pc = (pc != 0);
	}

	return (0);
}

/*
 * Determine the return address for the current frame.  Typically this is the
 * fr_savpc value from the current frame, but we also perform some special
 * handling to see if we are stopped on one of the first two instructions of
 * a typical function prologue, in which case %rbp will not be set up yet.
 */
int
mdb_amd64_step_out(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, kreg_t fp, kreg_t sp,
    mdb_instr_t curinstr)
{
	struct frame fr;
	GElf_Sym s;
	char buf[1];

	enum {
		M_PUSHQ_RBP	= 0x55,	/* pushq %rbp */
		M_REX_W		= 0x48, /* REX prefix with only W set */
		M_MOVL_RBP	= 0x8b	/* movq %rsp, %rbp with prefix */
	};

	if (mdb_tgt_lookup_by_addr(t, pc, MDB_TGT_SYM_FUZZY,
	    buf, 0, &s, NULL) == 0) {
		if (pc == s.st_value && curinstr == M_PUSHQ_RBP)
			fp = sp - 8;
		else if (pc == s.st_value + 1 && curinstr == M_REX_W) {
			if (mdb_tgt_vread(t, &curinstr, sizeof (curinstr),
			    pc + 1) == sizeof (curinstr) && curinstr ==
			    M_MOVL_RBP)
				fp = sp;
		}
	}

	if (mdb_tgt_vread(t, &fr, sizeof (fr), fp) == sizeof (fr)) {
		*p = fr.fr_savpc;
		return (0);
	}

	return (-1); /* errno is set for us */
}

/*ARGSUSED*/
int
mdb_amd64_next(mdb_tgt_t *t, uintptr_t *p, kreg_t pc, mdb_instr_t curinstr)
{
	mdb_tgt_addr_t npc;
	mdb_tgt_addr_t callpc;

	enum {
		M_CALL_REL = 0xe8, /* call near with relative displacement */
		M_CALL_REG = 0xff, /* call near indirect or call far register */

		M_REX_LO = 0x40,
		M_REX_HI = 0x4f
	};

	/*
	 * If the opcode is a near call with relative displacement, assume the
	 * displacement is a rel32 from the next instruction.
	 */
	if (curinstr == M_CALL_REL) {
		*p = pc + sizeof (mdb_instr_t) + sizeof (uint32_t);
		return (0);
	}

	/* Skip the rex prefix, if any */
	callpc = pc;
	while (curinstr >= M_REX_LO && curinstr <= M_REX_HI) {
		if (mdb_tgt_vread(t, &curinstr, sizeof (curinstr), ++callpc) !=
		    sizeof (curinstr))
			return (-1); /* errno is set for us */
	}

	if (curinstr != M_CALL_REG) {
		/* It's not a call */
		return (set_errno(EAGAIN));
	}

	if ((npc = mdb_dis_nextins(mdb.m_disasm, t, MDB_TGT_AS_VIRT, pc)) == pc)
		return (-1); /* errno is set for us */

	*p = npc;
	return (0);
}

/*ARGSUSED*/
int
mdb_amd64_kvm_frame(void *arglim, uintptr_t pc, uint_t argc, const long *argv,
    const mdb_tgt_gregset_t *gregs)
{
	argc = MIN(argc, (uintptr_t)arglim);
	mdb_printf("%a(", pc);

	if (argc != 0) {
		mdb_printf("%lr", *argv++);
		for (argc--; argc != 0; argc--)
			mdb_printf(", %lr", *argv++);
	}

	mdb_printf(")\n");
	return (0);
}

int
mdb_amd64_kvm_framev(void *arglim, uintptr_t pc, uint_t argc, const long *argv,
    const mdb_tgt_gregset_t *gregs)
{
	/*
	 * Historically adb limited stack trace argument display to a fixed-
	 * size number of arguments since no symbolic debugging info existed.
	 * On amd64 we can detect the true number of saved arguments so only
	 * respect an arglim of zero; otherwise display the entire argv[].
	 */
	if (arglim == 0)
		argc = 0;

	mdb_printf("%0?lr %a(", gregs->kregs[KREG_RBP], pc);

	if (argc != 0) {
		mdb_printf("%lr", *argv++);
		for (argc--; argc != 0; argc--)
			mdb_printf(", %lr", *argv++);
	}

	mdb_printf(")\n");
	return (0);
}