sdt.c   [plain text]

/*
 * 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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <miscfs/devfs/devfs.h>

#if defined(__arm__) || defined(__arm64__)
#include <arm/caches_internal.h>
#endif /* defined(__arm__) || defined(__arm64__) */

#include <sys/dtrace.h>
#include <sys/dtrace_impl.h>

#include <sys/dtrace_glue.h>

#include <sys/sdt_impl.h>
extern int dtrace_kernel_symbol_mode;

#include <ptrauth.h>

/* #include <machine/trap.h */
struct savearea_t; /* Used anonymously */

#if defined(__arm__)
typedef kern_return_t (*perfCallback)(int, struct savearea_t *, __unused int, __unused int);
extern perfCallback tempDTraceTrapHook;
extern kern_return_t fbt_perfCallback(int, struct savearea_t *, __unused int, __unused int);
#define SDT_PATCHVAL    0xdefc
#define SDT_AFRAMES             7
#elif defined(__arm64__)
typedef kern_return_t (*perfCallback)(int, struct savearea_t *, __unused int, __unused int);
extern perfCallback tempDTraceTrapHook;
extern kern_return_t fbt_perfCallback(int, struct savearea_t *, __unused int, __unused int);
#define SDT_PATCHVAL    0xe7eeee7e
#define SDT_AFRAMES             7
#elif defined(__x86_64__)
typedef kern_return_t (*perfCallback)(int, struct savearea_t *, uintptr_t *, int);
extern perfCallback tempDTraceTrapHook;
extern kern_return_t fbt_perfCallback(int, struct savearea_t *, uintptr_t *, int);
#define SDT_PATCHVAL    0xf0
#define SDT_AFRAMES             6
#else
#error Unknown architecture
#endif

#define SDT_PROBETAB_SIZE       0x1000          /* 4k entries -- 16K total */

#define DTRACE_PROBE_PREFIX "_dtrace_probe$"

static int                      sdt_verbose = 0;
sdt_probe_t             **sdt_probetab;
int                     sdt_probetab_size;
int                     sdt_probetab_mask;

/*ARGSUSED*/
static void
__sdt_provide_module(void *arg, struct modctl *ctl)
{
#pragma unused(arg)
	struct module *mp = (struct module *)ctl->mod_address;
	char *modname = ctl->mod_modname;
	sdt_probedesc_t *sdpd;
	sdt_probe_t *sdp, *old;
	sdt_provider_t *prov;

	/*
	 * One for all, and all for one:  if we haven't yet registered all of
	 * our providers, we'll refuse to provide anything.
	 */
	for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
		if (prov->sdtp_id == DTRACE_PROVNONE) {
			return;
		}
	}

	if (!mp || mp->sdt_nprobes != 0 || (sdpd = mp->sdt_probes) == NULL) {
		return;
	}

	for (sdpd = mp->sdt_probes; sdpd != NULL; sdpd = sdpd->sdpd_next) {
		const char *func;
		dtrace_id_t id;

		/* Validate probe's provider name. Do not provide probes for unknown providers. */
		for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
			if (strcmp(prov->sdtp_prefix, sdpd->sdpd_prov) == 0) {
				break;
			}
		}

		if (prov->sdtp_name == NULL) {
			printf("Ignoring probes from unsupported provider %s\n", sdpd->sdpd_prov);
			continue;
		}

		sdp = kmem_zalloc(sizeof(sdt_probe_t), KM_SLEEP);
		sdp->sdp_loadcnt = ctl->mod_loadcnt;
		sdp->sdp_ctl = ctl;
		sdp->sdp_name = kmem_alloc(strlen(sdpd->sdpd_name) + 1, KM_SLEEP);
		strncpy(sdp->sdp_name, sdpd->sdpd_name, strlen(sdpd->sdpd_name) + 1);
		sdp->sdp_namelen = strlen(sdpd->sdpd_name) + 1;
		sdp->sdp_provider = prov;

		func = (sdpd->sdpd_func != NULL) ? sdpd->sdpd_func : "<unknown>";

		/*
		 * We have our provider.  Now create the probe.
		 */
		if ((id = dtrace_probe_lookup(prov->sdtp_id, modname,
		    func, sdp->sdp_name)) != DTRACE_IDNONE) {
			old = dtrace_probe_arg(prov->sdtp_id, id);
			ASSERT(old != NULL);

			sdp->sdp_next = old->sdp_next;
			sdp->sdp_id = id;
			old->sdp_next = sdp;
		} else {
			sdp->sdp_id = dtrace_probe_create(prov->sdtp_id,
			    modname, func, sdp->sdp_name, SDT_AFRAMES, sdp);

			mp->sdt_nprobes++;
		}

#if 0
		printf("__sdt_provide_module:  sdpd=0x%p  sdp=0x%p  name=%s, id=%d\n", sdpd, sdp,
		    sdp->sdp_name, sdp->sdp_id);
#endif

		sdp->sdp_hashnext =
		    sdt_probetab[SDT_ADDR2NDX(sdpd->sdpd_offset)];
		sdt_probetab[SDT_ADDR2NDX(sdpd->sdpd_offset)] = sdp;

		sdp->sdp_patchval = SDT_PATCHVAL;
		sdp->sdp_patchpoint = (sdt_instr_t *)sdpd->sdpd_offset;
		sdp->sdp_savedval = *sdp->sdp_patchpoint;
	}
}

/*ARGSUSED*/
static void
sdt_destroy(void *arg, dtrace_id_t id, void *parg)
{
#pragma unused(arg,id)
	sdt_probe_t *sdp = parg, *old, *last, *hash;
	int ndx;

#if !defined(__APPLE__)
	/*
	 * APPLE NOTE:  sdt probes for kexts not yet implemented
	 */
	struct modctl *ctl = sdp->sdp_ctl;

	if (ctl != NULL && ctl->mod_loadcnt == sdp->sdp_loadcnt) {
		if ((ctl->mod_loadcnt == sdp->sdp_loadcnt &&
		    ctl->mod_loaded)) {
			((struct module *)(ctl->mod_mp))->sdt_nprobes--;
		}
	}
#endif /* __APPLE__ */

	while (sdp != NULL) {
		old = sdp;

		/*
		 * Now we need to remove this probe from the sdt_probetab.
		 */
		ndx = SDT_ADDR2NDX(sdp->sdp_patchpoint);
		last = NULL;
		hash = sdt_probetab[ndx];

		while (hash != sdp) {
			ASSERT(hash != NULL);
			last = hash;
			hash = hash->sdp_hashnext;
		}

		if (last != NULL) {
			last->sdp_hashnext = sdp->sdp_hashnext;
		} else {
			sdt_probetab[ndx] = sdp->sdp_hashnext;
		}

		kmem_free(sdp->sdp_name, sdp->sdp_namelen);
		sdp = sdp->sdp_next;
		kmem_free(old, sizeof(sdt_probe_t));
	}
}

/*ARGSUSED*/
static int
sdt_enable(void *arg, dtrace_id_t id, void *parg)
{
#pragma unused(arg,id)
	sdt_probe_t *sdp = parg;
	struct modctl *ctl = sdp->sdp_ctl;

	ctl->mod_nenabled++;

	/*
	 * If this module has disappeared since we discovered its probes,
	 * refuse to enable it.
	 */
	if (!ctl->mod_loaded) {
		if (sdt_verbose) {
			cmn_err(CE_NOTE, "sdt is failing for probe %s "
			    "(module %s unloaded)",
			    sdp->sdp_name, ctl->mod_modname);
		}
		goto err;
	}

	/*
	 * Now check that our modctl has the expected load count.  If it
	 * doesn't, this module must have been unloaded and reloaded -- and
	 * we're not going to touch it.
	 */
	if (ctl->mod_loadcnt != sdp->sdp_loadcnt) {
		if (sdt_verbose) {
			cmn_err(CE_NOTE, "sdt is failing for probe %s "
			    "(module %s reloaded)",
			    sdp->sdp_name, ctl->mod_modname);
		}
		goto err;
	}

	dtrace_casptr(&tempDTraceTrapHook, NULL, ptrauth_nop_cast(void *, &fbt_perfCallback));
	if (tempDTraceTrapHook != (perfCallback)fbt_perfCallback) {
		if (sdt_verbose) {
			cmn_err(CE_NOTE, "sdt_enable is failing for probe %s "
			    "in module %s: tempDTraceTrapHook already occupied.",
			    sdp->sdp_name, ctl->mod_modname);
		}
		return 0;
	}

	while (sdp != NULL) {
		(void)ml_nofault_copy((vm_offset_t)&sdp->sdp_patchval, (vm_offset_t)sdp->sdp_patchpoint,
		    (vm_size_t)sizeof(sdp->sdp_patchval));

		/*
		 * Make the patched instruction visible via a data + instruction
		 * cache fush on platforms that need it
		 */
		flush_dcache((vm_offset_t)sdp->sdp_patchpoint, (vm_size_t)sizeof(sdp->sdp_patchval), 0);
		invalidate_icache((vm_offset_t)sdp->sdp_patchpoint, (vm_size_t)sizeof(sdp->sdp_patchval), 0);

		sdp = sdp->sdp_next;
	}

err:
	return 0;
}

/*ARGSUSED*/
static void
sdt_disable(void *arg, dtrace_id_t id, void *parg)
{
#pragma unused(arg,id)
	sdt_probe_t *sdp = parg;
	struct modctl *ctl = sdp->sdp_ctl;

	ctl->mod_nenabled--;

	if (!ctl->mod_loaded || ctl->mod_loadcnt != sdp->sdp_loadcnt) {
		goto err;
	}

	while (sdp != NULL) {
		(void)ml_nofault_copy((vm_offset_t)&sdp->sdp_savedval, (vm_offset_t)sdp->sdp_patchpoint,
		    (vm_size_t)sizeof(sdp->sdp_savedval));
		/*
		 * Make the patched instruction visible via a data + instruction
		 * cache flush on platforms that need it
		 */
		flush_dcache((vm_offset_t)sdp->sdp_patchpoint, (vm_size_t)sizeof(sdp->sdp_savedval), 0);
		invalidate_icache((vm_offset_t)sdp->sdp_patchpoint, (vm_size_t)sizeof(sdp->sdp_savedval), 0);
		sdp = sdp->sdp_next;
	}

err:
	;
}

static dtrace_pops_t sdt_pops = {
	.dtps_provide =         NULL,
	.dtps_provide_module =  sdt_provide_module,
	.dtps_enable =          sdt_enable,
	.dtps_disable =         sdt_disable,
	.dtps_suspend =         NULL,
	.dtps_resume =          NULL,
	.dtps_getargdesc =      sdt_getargdesc,
	.dtps_getargval =       sdt_getarg,
	.dtps_usermode =        NULL,
	.dtps_destroy =         sdt_destroy,
};

/*ARGSUSED*/
static int
sdt_attach(dev_info_t *devi)
{
	sdt_provider_t *prov;

	if (ddi_create_minor_node(devi, "sdt", S_IFCHR,
	    0, DDI_PSEUDO, 0) == DDI_FAILURE) {
		cmn_err(CE_NOTE, "/dev/sdt couldn't create minor node");
		ddi_remove_minor_node(devi, NULL);
		return DDI_FAILURE;
	}

	if (sdt_probetab_size == 0) {
		sdt_probetab_size = SDT_PROBETAB_SIZE;
	}

	sdt_probetab_mask = sdt_probetab_size - 1;
	sdt_probetab =
	    kmem_zalloc(sdt_probetab_size * sizeof(sdt_probe_t *), KM_SLEEP);
	dtrace_invop_add(sdt_invop);

	for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
		if (dtrace_register(prov->sdtp_name, prov->sdtp_attr,
		    DTRACE_PRIV_KERNEL, NULL,
		    &sdt_pops, prov, &prov->sdtp_id) != 0) {
			cmn_err(CE_WARN, "failed to register sdt provider %s",
			    prov->sdtp_name);
		}
	}

	return DDI_SUCCESS;
}

/*
 * APPLE NOTE:  sdt_detach not implemented
 */
#if !defined(__APPLE__)
/*ARGSUSED*/
static int
sdt_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
	sdt_provider_t *prov;

	switch (cmd) {
	case DDI_DETACH:
		break;

	case DDI_SUSPEND:
		return DDI_SUCCESS;

	default:
		return DDI_FAILURE;
	}

	for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
		if (prov->sdtp_id != DTRACE_PROVNONE) {
			if (dtrace_unregister(prov->sdtp_id) != 0) {
				return DDI_FAILURE;
			}

			prov->sdtp_id = DTRACE_PROVNONE;
		}
	}

	dtrace_invop_remove(sdt_invop);
	kmem_free(sdt_probetab, sdt_probetab_size * sizeof(sdt_probe_t *));

	return DDI_SUCCESS;
}
#endif /* __APPLE__ */

d_open_t _sdt_open;

int
_sdt_open(dev_t dev, int flags, int devtype, struct proc *p)
{
#pragma unused(dev,flags,devtype,p)
	return 0;
}

#define SDT_MAJOR  -24 /* let the kernel pick the device number */

static const struct cdevsw sdt_cdevsw =
{
	.d_open = _sdt_open,
	.d_close = eno_opcl,
	.d_read = eno_rdwrt,
	.d_write = eno_rdwrt,
	.d_ioctl = eno_ioctl,
	.d_stop = (stop_fcn_t *)nulldev,
	.d_reset = (reset_fcn_t *)nulldev,
	.d_select = eno_select,
	.d_mmap = eno_mmap,
	.d_strategy = eno_strat,
	.d_reserved_1 = eno_getc,
	.d_reserved_2 = eno_putc,
};

static struct modctl g_sdt_kernctl;
static struct module g_sdt_mach_module;

#include <mach-o/nlist.h>
#include <libkern/kernel_mach_header.h>

/*
 * Represents single record in __DATA,__sdt section.
 */
typedef struct dtrace_sdt_def {
	uintptr_t      dsd_addr;    /* probe site location */
	const char     *dsd_prov;   /* provider's name */
	const char     *dsd_name;   /* probe's name */
} __attribute__((__packed__))  dtrace_sdt_def_t;

/*
 * Creates a copy of name and unescapes '-' characters.
 */
static char *
sdt_strdup_name(const char *name)
{
	size_t len = strlen(name) + 1;
	size_t i, j;
	char *nname = kmem_alloc(len, KM_SLEEP);

	for (i = 0, j = 0; name[j] != '\0'; i++) {
		if (name[j] == '_' && name[j + 1] == '_') {
			nname[i] = '-';
			j += 2;
		} else {
			nname[i] = name[j++];
		}
	}

	nname[i] = '\0';
	return nname;
}

void
sdt_early_init( void )
{
	if (dtrace_sdt_probes_restricted()) {
		return;
	}
	if (MH_MAGIC_KERNEL != _mh_execute_header.magic) {
		g_sdt_kernctl.mod_address = (vm_address_t)NULL;
		g_sdt_kernctl.mod_size = 0;
	} else {
		kernel_mach_header_t        *mh;
		struct load_command         *cmd;
		kernel_segment_command_t    *orig_ts = NULL, *orig_le = NULL;
		kernel_section_t            *orig_dt = NULL;
		struct symtab_command       *orig_st = NULL;
		kernel_nlist_t              *sym = NULL;
		char                        *strings;
		unsigned int                i;
		unsigned int                len;

		g_sdt_mach_module.sdt_nprobes = 0;
		g_sdt_mach_module.sdt_probes = NULL;

		g_sdt_kernctl.mod_address = (vm_address_t)&g_sdt_mach_module;
		g_sdt_kernctl.mod_size = 0;
		strncpy((char *)&(g_sdt_kernctl.mod_modname), "mach_kernel", KMOD_MAX_NAME);

		g_sdt_kernctl.mod_next = NULL;
		g_sdt_kernctl.mod_stale = NULL;
		g_sdt_kernctl.mod_id = 0;
		g_sdt_kernctl.mod_loadcnt = 1;
		g_sdt_kernctl.mod_loaded = 1;
		g_sdt_kernctl.mod_flags = 0;
		g_sdt_kernctl.mod_nenabled = 0;

		mh = &_mh_execute_header;
		cmd = (struct load_command*) &mh[1];
		for (i = 0; i < mh->ncmds; i++) {
			if (cmd->cmd == LC_SEGMENT_KERNEL) {
				kernel_segment_command_t *orig_sg = (kernel_segment_command_t *) cmd;

				if (LIT_STRNEQL(orig_sg->segname, SEG_TEXT)) {
					orig_ts = orig_sg;
				} else if (LIT_STRNEQL(orig_sg->segname, SEG_LINKEDIT)) {
					orig_le = orig_sg;
				} else if (LIT_STRNEQL(orig_sg->segname, "")) {
					orig_ts = orig_sg; /* kexts have a single unnamed segment */
				}
			} else if (cmd->cmd == LC_SYMTAB) {
				orig_st = (struct symtab_command *) cmd;
			}

			cmd = (struct load_command *) ((uintptr_t) cmd + cmd->cmdsize);
		}

		/* Locate DTrace SDT section in the object. */
		if ((orig_dt = getsectbyname("__DATA", "__sdt")) == NULL) {
			printf("DTrace section not found.\n");
			return;
		}

		if ((orig_ts == NULL) || (orig_st == NULL) || (orig_le == NULL)) {
			return;
		}

		sym = (kernel_nlist_t *)(orig_le->vmaddr + orig_st->symoff - orig_le->fileoff);
		strings = (char *)(orig_le->vmaddr + orig_st->stroff - orig_le->fileoff);

		/*
		 * Iterate over SDT section and establish all SDT probes.
		 */
		dtrace_sdt_def_t *sdtdef = (dtrace_sdt_def_t *)(orig_dt->addr);
		for (size_t k = 0; k < orig_dt->size / sizeof(dtrace_sdt_def_t); k++, sdtdef++) {
			const char *funcname;
			unsigned long best;

			sdt_probedesc_t *sdpd = kmem_alloc(sizeof(sdt_probedesc_t), KM_SLEEP);

			/* Unescape probe name and keep a note of the size of original memory allocation. */
			sdpd->sdpd_name = sdt_strdup_name(sdtdef->dsd_name);
			sdpd->sdpd_namelen = strlen(sdtdef->dsd_name) + 1;

			/* Used only for provider structure lookup so there is no need to make dynamic copy. */
			sdpd->sdpd_prov = sdtdef->dsd_prov;

			/*
			 * Find the symbol immediately preceding the sdt probe site just discovered,
			 * that symbol names the function containing the sdt probe.
			 */
			funcname = "<unknown>";
			for (i = 0; i < orig_st->nsyms; i++) {
				uint8_t jn_type = sym[i].n_type & N_TYPE;
				char *jname = strings + sym[i].n_un.n_strx;

				if ((N_SECT != jn_type && N_ABS != jn_type)) {
					continue;
				}

				if (0 == sym[i].n_un.n_strx) { /* iff a null, "", name. */
					continue;
				}

				if (*jname == '_') {
					jname += 1;
				}

				if (sdtdef->dsd_addr <= (unsigned long)sym[i].n_value) {
					continue;
				}

				if ((unsigned long)sym[i].n_value > best) {
					best = (unsigned long)sym[i].n_value;
					funcname = jname;
				}
			}

			len = strlen(funcname) + 1;
			sdpd->sdpd_func = kmem_alloc(len, KM_SLEEP);
			strncpy(sdpd->sdpd_func, funcname, len);

			sdpd->sdpd_offset = sdtdef->dsd_addr;
#if defined(__arm__)
			/* PR8353094 - mask off thumb-bit */
			sdpd->sdpd_offset &= ~0x1U;
#elif defined(__arm64__)
			sdpd->sdpd_offset &= ~0x1LU;
#endif  /* __arm__ */

			sdpd->sdpd_next = g_sdt_mach_module.sdt_probes;
			g_sdt_mach_module.sdt_probes = sdpd;
		}
	}
}

void
sdt_init( void )
{
	int majdevno = cdevsw_add(SDT_MAJOR, &sdt_cdevsw);

	if (majdevno < 0) {
		printf("sdt_init: failed to allocate a major number!\n");
		return;
	}

	if (dtrace_sdt_probes_restricted()) {
		return;
	}

	sdt_attach((dev_info_t*)(uintptr_t)majdevno);
}

#undef SDT_MAJOR

/*ARGSUSED*/
void
sdt_provide_module(void *arg, struct modctl *ctl)
{
#pragma unused(arg)
	ASSERT(ctl != NULL);
	ASSERT(dtrace_kernel_symbol_mode != DTRACE_KERNEL_SYMBOLS_NEVER);
	LCK_MTX_ASSERT(&mod_lock, LCK_MTX_ASSERT_OWNED);

	if (MOD_SDT_DONE(ctl)) {
		return;
	}

	if (MOD_IS_MACH_KERNEL(ctl)) {
		__sdt_provide_module(arg, &g_sdt_kernctl);

		sdt_probedesc_t *sdpd = g_sdt_mach_module.sdt_probes;
		while (sdpd) {
			sdt_probedesc_t *this_sdpd = sdpd;
			kmem_free((void *)sdpd->sdpd_name, sdpd->sdpd_namelen);
			kmem_free((void *)sdpd->sdpd_func, strlen(sdpd->sdpd_func) + 1);
			sdpd = sdpd->sdpd_next;
			kmem_free((void *)this_sdpd, sizeof(sdt_probedesc_t));
		}
		g_sdt_mach_module.sdt_probes = NULL;
	} else {
		/*
		 * APPLE NOTE:  sdt probes for kexts not yet implemented
		 */
	}

	/* Need to mark this module as completed */
	ctl->mod_flags |= MODCTL_SDT_PROBES_PROVIDED;
}