/*
 * 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
 *
 * Portions Copyright 2006-2008 John Birrell jb@freebsd.org
 * Portions Copyright 2013 Justin Hibbits jhibbits@freebsd.org
 * Portions Copyright 2013 Howard Su howardsu@freebsd.org
 * Portions Copyright 2015 Ruslan Bukin <br@bsdpad.com>
 */

/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/cdefs.h>
#include <sys/param.h>

#include <sys/dtrace.h>

#include "fbt.h"

#define	AARCH64_BRK		0xd4200000
#define	AARCH64_BRK_IMM16_SHIFT	5
#define	AARCH64_BRK_IMM16_VAL	(0x40d << AARCH64_BRK_IMM16_SHIFT)
#define	FBT_PATCHVAL		(AARCH64_BRK | AARCH64_BRK_IMM16_VAL)
#define	FBT_AFRAMES	4

int
fbt_invop(uintptr_t addr, struct trapframe *frame, uintptr_t rval)
{
	solaris_cpu_t *cpu;
	fbt_probe_t *fbt;

	cpu = &solaris_cpu[curcpu];
	fbt = fbt_probetab[FBT_ADDR2NDX(addr)];

	for (; fbt != NULL; fbt = fbt->fbtp_hashnext) {
		if ((uintptr_t)fbt->fbtp_patchpoint != addr)
			continue;

		cpu->cpu_dtrace_caller = addr;

		if (fbt->fbtp_roffset == 0) {
			dtrace_probe(fbt->fbtp_id, frame->tf_x[0],
			    frame->tf_x[1], frame->tf_x[2],
			    frame->tf_x[3], frame->tf_x[4]);
		} else {
			dtrace_probe(fbt->fbtp_id, fbt->fbtp_roffset, rval,
			    0, 0, 0);
		}
		cpu->cpu_dtrace_caller = 0;
		return (fbt->fbtp_savedval);
	}

	return (0);
}

void
fbt_patch_tracepoint(fbt_probe_t *fbt, fbt_patchval_t val)
{
	vm_offset_t addr;

	if (!arm64_get_writable_addr((vm_offset_t)fbt->fbtp_patchpoint, &addr))
		panic("%s: Unable to write new instruction", __func__);

	*(fbt_patchval_t *)addr = val;
	cpu_icache_sync_range((vm_offset_t)fbt->fbtp_patchpoint, 4);
}

int
fbt_provide_module_function(linker_file_t lf, int symindx,
    linker_symval_t *symval, void *opaque)
{
	fbt_probe_t *fbt, *retfbt;
	uint32_t *target, *start;
	uint32_t *instr, *limit;
	const char *name;
	char *modname;
	bool found;
	int offs;

	modname = opaque;
	name = symval->name;

	/* Check if function is excluded from instrumentation */
	if (fbt_excluded(name))
		return (0);

	/*
	 * Instrumenting certain exception handling functions can lead to FBT
	 * recursion, so exclude from instrumentation.
	 */
	 if (strcmp(name, "handle_el1h_sync") == 0 ||
	    strcmp(name, "do_el1h_sync") == 0)
		return (1);

	instr = (uint32_t *)(symval->value);
	limit = (uint32_t *)(symval->value + symval->size);

	/*
	 * Ignore any bti instruction at the start of the function
	 * we need to keep it there for any indirect branches calling
	 * the function on Armv8.5+
	 */
	if ((*instr & BTI_MASK) == BTI_INSTR)
		instr++;

	/* Look for stp (pre-indexed) operation */
	found = false;
	/*
	 * If the first instruction is a nop it's a specially marked
	 * asm function. We only support a nop first as it's not a normal
	 * part of the function prologue.
	 */
	if (*instr == NOP_INSTR)
		found = true;
	if (!found) {
		for (; instr < limit; instr++) {
			/*
			 * Some functions start with
			 * "stp xt1, xt2, [xn, <const>]!"
			 */
			if ((*instr & LDP_STP_MASK) == STP_64) {
				/*
				 * Assume any other store of this type means we
				 * are past the function prolog.
				 */
				if (((*instr >> ADDR_SHIFT) & ADDR_MASK) == 31)
					found = true;
				break;
			}

			/*
			 * Some functions start with a "sub sp, sp, <const>"
			 * Sometimes the compiler will have a sub instruction
			 * that is not of the above type so don't stop if we
			 * see one.
			 */
			if ((*instr & SUB_MASK) == SUB_INSTR &&
			    ((*instr >> SUB_RD_SHIFT) & SUB_R_MASK) == 31 &&
			    ((*instr >> SUB_RN_SHIFT) & SUB_R_MASK) == 31) {
				found = true;
				break;
			}
		}
	}

	if (!found)
		return (0);

	fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
	fbt->fbtp_name = name;
	fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
	    name, FBT_ENTRY, FBT_AFRAMES, fbt);
	fbt->fbtp_patchpoint = instr;
	fbt->fbtp_ctl = lf;
	fbt->fbtp_loadcnt = lf->loadcnt;
	fbt->fbtp_savedval = *instr;
	fbt->fbtp_patchval = FBT_PATCHVAL;
	if ((*instr & SUB_MASK) == SUB_INSTR)
		fbt->fbtp_rval = DTRACE_INVOP_SUB;
	else
		fbt->fbtp_rval = DTRACE_INVOP_STP;
	fbt->fbtp_symindx = symindx;

	fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
	fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;

	lf->fbt_nentries++;

	retfbt = NULL;
again:
	for (; instr < limit; instr++) {
		if (*instr == RET_INSTR)
			break;
		else if ((*instr & B_MASK) == B_INSTR) {
			offs = (*instr & B_DATA_MASK);
			offs *= 4;
			target = (instr + offs);
			start = (uint32_t *)symval->value;
			if (target >= limit || target < start)
				break;
		}
	}

	if (instr >= limit)
		return (0);

	/*
	 * We have a winner!
	 */
	fbt = malloc(sizeof (fbt_probe_t), M_FBT, M_WAITOK | M_ZERO);
	fbt->fbtp_name = name;
	if (retfbt == NULL) {
		fbt->fbtp_id = dtrace_probe_create(fbt_id, modname,
		    name, FBT_RETURN, FBT_AFRAMES, fbt);
	} else {
		retfbt->fbtp_probenext = fbt;
		fbt->fbtp_id = retfbt->fbtp_id;
	}
	retfbt = fbt;

	fbt->fbtp_patchpoint = instr;
	fbt->fbtp_ctl = lf;
	fbt->fbtp_loadcnt = lf->loadcnt;
	fbt->fbtp_symindx = symindx;
	if ((*instr & B_MASK) == B_INSTR)
		fbt->fbtp_rval = DTRACE_INVOP_B;
	else
		fbt->fbtp_rval = DTRACE_INVOP_RET;
	fbt->fbtp_roffset = (uintptr_t)instr - (uintptr_t)symval->value;
	fbt->fbtp_savedval = *instr;
	fbt->fbtp_patchval = FBT_PATCHVAL;
	fbt->fbtp_hashnext = fbt_probetab[FBT_ADDR2NDX(instr)];
	fbt_probetab[FBT_ADDR2NDX(instr)] = fbt;

	lf->fbt_nentries++;

	instr++;
	goto again;
}