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/usr/share/systemtap/runtime/linux

Name	Size	Mode	Actions
uprobes/	-	0755	rm
uprobes2/	-	0755	rm
access_process_vm.h	4311	0644	edit dl rm
addr-map.c	9749	0644	edit dl rm
alloc.c	15900	0644	edit dl rm
arith.c	16799	0644	edit dl rm
autoconf-514-panic.c	68	0644	edit dl rm
autoconf-access_ok_2args.c	90	0644	edit dl rm
autoconf-alloc-percpu-align.c	118	0644	edit dl rm
autoconf-asm-syscall.c	51	0644	edit dl rm
autoconf-atomic_fetch_add_unless.c	94	0644	edit dl rm
autoconf-bio-bi_opf.c	824	0644	edit dl rm
autoconf-blk-types.c	359	0644	edit dl rm
autoconf-compat-utimbuf.c	53	0644	edit dl rm
autoconf-compat_sigaction.c	448	0644	edit dl rm
autoconf-constant-tsc.c	63	0644	edit dl rm
autoconf-cpu-clock.c	1277	0644	edit dl rm
autoconf-dpath-path.c	121	0644	edit dl rm
autoconf-files_lookup_fd_raw.c	136	0644	edit dl rm
autoconf-from_kuid_munged.c	191	0644	edit dl rm
autoconf-fs_supers-hlist.c	354	0644	edit dl rm
autoconf-generated-compile.c	56	0644	edit dl rm
autoconf-genhd.c	201	0644	edit dl rm
autoconf-get-kretprobe.c	107	0644	edit dl rm
autoconf-get_user_pages-flags.c	1549	0644	edit dl rm
autoconf-get_user_pages-notask_struct.c	1301	0644	edit dl rm
autoconf-get_user_pages_remote-flags.c	1550	0644	edit dl rm
autoconf-get_user_pages_remote-flags_locked.c	1331	0644	edit dl rm
autoconf-get_user_pages_remote-notask_struct.c	1438	0644	edit dl rm
autoconf-grsecurity.c	219	0644	edit dl rm
autoconf-hlist-4args.c	296	0644	edit dl rm
autoconf-hlist_add_tail_rcu.c	112	0644	edit dl rm
autoconf-hrtimer-getset-expires.c	126	0644	edit dl rm
autoconf-hrtimer-rel.c	87	0644	edit dl rm
autoconf-hw_breakpoint_context.c	315	0644	edit dl rm
autoconf-inode-private.c	173	0644	edit dl rm
autoconf-inode-rwsem.c	172	0644	edit dl rm
autoconf-inode-uretprobes.c	264	0644	edit dl rm
autoconf-kernel_read-new-args.c	1030	0644	edit dl rm
autoconf-kprobe-symbol-name.c	90	0644	edit dl rm
autoconf-ktime-get-real.c	98	0644	edit dl rm
autoconf-linux-sched_headers.c	1678	0644	edit dl rm
autoconf-local-clock.c	1282	0644	edit dl rm
autoconf-lockdown-debugfs.c	102	0644	edit dl rm
autoconf-lockdown-kernel.c	90	0644	edit dl rm
autoconf-mm-context-vdso-base.c	117	0644	edit dl rm
autoconf-mm-context-vdso.c	114	0644	edit dl rm
autoconf-mm-shmempages.c	72	0644	edit dl rm
autoconf-mmap_lock.c	175	0644	edit dl rm
autoconf-module-sect-attrs.c	158	0644	edit dl rm
autoconf-module_layout.c	52	0644	edit dl rm
autoconf-mod_kallsyms.c	51	0644	edit dl rm
autoconf-nameidata.c	96	0644	edit dl rm
autoconf-netfilter-4_1.c	769	0644	edit dl rm
autoconf-netfilter-4_4.c	1460	0644	edit dl rm
autoconf-netfilter-313b.c	602	0644	edit dl rm
autoconf-netfilter.c	422	0644	edit dl rm
autoconf-old-inode-uprobes.c	357	0644	edit dl rm
autoconf-oneachcpu-retry.c	957	0644	edit dl rm
autoconf-pagefault_disable.c	137	0644	edit dl rm
autoconf-pde_data.c	226	0644	edit dl rm
autoconf-perf-structpid.c	444	0644	edit dl rm
autoconf-procfs-owner.c	158	0644	edit dl rm
autoconf-proc_ops.c	566	0644	edit dl rm
autoconf-rcu_is_watching.c	385	0644	edit dl rm
autoconf-real-parent.c	427	0644	edit dl rm
autoconf-regset.c	239	0644	edit dl rm
autoconf-relay-umode_t.c	730	0644	edit dl rm
autoconf-relay_buf-per_cpu_ptr.c	920	0644	edit dl rm
autoconf-ring_buffer-flags.c	112	0644	edit dl rm
autoconf-ring_buffer_lost_events.c	296	0644	edit dl rm
autoconf-ring_buffer_read_prepare.c	181	0644	edit dl rm
autoconf-save-stack-trace-no-bp.c	498	0644	edit dl rm
autoconf-save-stack-trace.c	501	0644	edit dl rm
autoconf-set_fs.c	221	0644	edit dl rm
autoconf-smpcall-4args.c	166	0644	edit dl rm
autoconf-smpcall-5args.c	169	0644	edit dl rm
autoconf-stack-trace-save-regs.c	176	0644	edit dl rm
autoconf-stacktrace_ops-int-address.c	409	0644	edit dl rm
autoconf-stacktrace_ops-warning.c	188	0644	edit dl rm
autoconf-syscall_get_args_3args.c	239	0644	edit dl rm
autoconf-task-state.c	550	0644	edit dl rm
autoconf-task-uid.c	152	0644	edit dl rm
autoconf-task_work-struct.c	219	0644	edit dl rm
autoconf-time32-old.c	52	0644	edit dl rm
autoconf-time32.c	53	0644	edit dl rm
autoconf-timerfd.c	232	0644	edit dl rm
autoconf-trace-printk.c	151	0644	edit dl rm
autoconf-tracepoint-has-data.c	493	0644	edit dl rm
autoconf-tracepoint-strings.c	233	0644	edit dl rm
autoconf-uaccess.c	28	0644	edit dl rm
autoconf-uapi-mount.c	52	0644	edit dl rm
autoconf-udelay_simple.c	90	0644	edit dl rm
autoconf-uidgid.c	50	0644	edit dl rm
autoconf-unwind-stack-trace.c	326	0644	edit dl rm
autoconf-uprobe-get-pc.c	374	0644	edit dl rm
autoconf-utrace-regset.c	273	0644	edit dl rm
autoconf-utrace-via-tracepoints.c	1712	0644	edit dl rm
autoconf-vm-area-pte.c	141	0644	edit dl rm
autoconf-walk-stack.c	217	0644	edit dl rm
autoconf-x86-fs.c	90	0644	edit dl rm
autoconf-x86-gs.c	90	0644	edit dl rm
autoconf-x86-uniregs.c	140	0644	edit dl rm
autoconf-x86-xfs.c	91	0644	edit dl rm
common_session_state.h	3249	0644	edit dl rm
compat_net.h	858	0644	edit dl rm
compat_structs.h	4409	0644	edit dl rm
compat_unistd.h	68384	0644	edit dl rm
copy.c	2717	0644	edit dl rm
debug.h	2978	0644	edit dl rm
io.c	5291	0644	edit dl rm
itrace.c	14874	0644	edit dl rm
kprobes.c	25126	0644	edit dl rm
loc2c-runtime.h	29874	0644	edit dl rm
map_list.h	1220	0644	edit dl rm
map_runtime.h	5266	0644	edit dl rm
namespaces.h	7128	0644	edit dl rm
netfilter.c	1410	0644	edit dl rm
perf.c	7596	0644	edit dl rm
perf.h	1272	0644	edit dl rm
perf_event_counter_context.c	336	0644	edit dl rm
perf_probe_handler_nmi.c	278	0644	edit dl rm
perf_read.h	959	0644	edit dl rm
print.c	11402	0644	edit dl rm
probe_lock.h	1807	0644	edit dl rm
regs-ia64.c	3741	0644	edit dl rm
regs.c	13490	0644	edit dl rm
runtime.h	12591	0644	edit dl rm
runtime_context.h	6089	0644	edit dl rm
runtime_defines.h	1041	0644	edit dl rm
stap_mmap_lock.h	343	0644	edit dl rm
stat_runtime.h	1774	0644	edit dl rm
stp_tls.h	1181	0644	edit dl rm
stp_tracepoint.c	11481	0644	edit dl rm
stp_tracepoint.h	2270	0644	edit dl rm
syscalls-common.h	976	0644	edit dl rm
task_finder.c	53860	0644	edit dl rm
task_finder2.c	57640	0644	edit dl rm
task_finder_map.c	5194	0644	edit dl rm
task_finder_stubs.c	2442	0644	edit dl rm
task_work_compatibility.h	1283	0644	edit dl rm
timer.c	2200	0644	edit dl rm
timer.h	1383	0644	edit dl rm
timer_compatibility.h	2317	0644	edit dl rm
uprobes-common.c	15573	0644	edit dl rm
uprobes-common.h	1653	0644	edit dl rm
uprobes-inc.h	484	0644	edit dl rm
uprobes-inode.c	34086	0644	edit dl rm

Edit: /usr/share/systemtap/runtime/linux/kprobes.c (25126B)

/* -*- linux-c -*-
 * Common functions for using kprobes
 * Copyright (C) 2014-2015 Red Hat Inc.
 *
 * This file is part of systemtap, and is free software.  You can
 * redistribute it and/or modify it under the terms of the GNU General
 * Public License (GPL); either version 2, or (at your option) any
 * later version.
 */

#ifndef _KPROBES_C_
#define _KPROBES_C_

// Warn of misconfigured kernels
#if !defined(CONFIG_KPROBES)
#error "Need CONFIG_KPROBES!"
#endif

// PR26074: if kallsyms_on_each_symbol() is not exported we try to get it via relocations.
// Need to define the runtime.h variable here to check if it's defined from kprobes.c.
// (This code would go in a header if it were used anywhere else.)
//
// PR11514: kallsyms_on_each_symbol() should not be used on PPC64.
#ifndef CONFIG_PPC64
#define STAPCONF_KALLSYMS_ON_EACH_SYMBOL
#if !defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL_EXPORTED)
extern void *_stp_kallsyms_on_each_symbol;
#endif
#endif

#if defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL) && defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL_EXPORTED)
#define USE_KALLSYMS_ON_EACH_SYMBOL (1)
#elif defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL)
// XXX May not be available; if available, is passed through relocation:
#define USE_KALLSYMS_ON_EACH_SYMBOL (_stp_kallsyms_on_each_symbol != NULL)
#else
#define USE_KALLSYMS_ON_EACH_SYMBOL (0)
#endif

#include <linux/kprobes.h>
#include <linux/module.h>

#ifdef DEBUG_KPROBES
#define dbug_stapkp(args...) do {					\
		_stp_dbug(__FUNCTION__, __LINE__, args);		\
	} while (0)
#define dbug_stapkp_cond(cond, args...) do {				\
		if (cond)						\
			dbug_stapkp(args);				\
	} while (0)
#else
#define dbug_stapkp(args...) do { } while (0)
#define dbug_stapkp_cond(cond, args...)  do { } while (0)
#endif

#ifndef KRETACTIVE
#define KRETACTIVE (max(15, 6 * (int)num_possible_cpus()))
#endif

// This shouldn't happen, but check as a precaution. If we're on kver >= 2.6.30,
// then we must also have STP_ON_THE_FLY_TIMER_ENABLE (which is turned on for
// kver >= 2.6.17, see translate_pass()). This indicates that the background
// timer is available and thus that kprobes can be armed/disarmed on-the-fly.
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30) \
      && !defined(STP_ON_THE_FLY_TIMER_ENABLE)
#error "STP_ON_THE_FLY_TIMER_ENABLE undefined"
#endif

// NB: this struct is set up by the stapkp_prepare_* functions prior to
// registering and zero'ed out again after each unregister
struct stap_kprobe {
   union { struct kprobe kp; struct kretprobe krp; } u;
   #ifdef __ia64__
   // PR6028: We register a second dummy probe at the same address so that the
   // kernel uses aggr_kprobe. This is needed ensure that the bspcache is always
   // valid.
   struct kprobe dummy;
   #endif
};

struct stap_kprobe_probe {
   const unsigned return_p:1;
   const unsigned maxactive_p:1;
   const unsigned optional_p:1;
   unsigned registered_p:1;
   const unsigned short maxactive_val;

// data saved in the kretprobe_instance packet
   const unsigned short saved_longs;
   const unsigned short saved_strings;

// These macros declare the module and section strings as either const char[]
   // or const char * const. Their actual types are determined at translate-time
   // in dwarf_derived_probe_group::emit_module_decls().
   STAP_KPROBE_PROBE_STR_module;
   STAP_KPROBE_PROBE_STR_section;

// For the majority of dwarf-based kprobes, we'll use address-based
   // probing. But, for dwarf-based kprobes in modules, we need to
   // switch to using symbol_name+offset (on kernels that support
   // symbol_name+offset probing).
   const unsigned long address;

// Note we can't really check for STAPCONF_KPROBE_SYMBOL_NAME here,
   // since that complicates the init logic too much.
   const char *symbol_name;
   unsigned int offset;

const struct stap_probe * const probe;
   const struct stap_probe * const entry_probe;
   struct stap_kprobe * const kprobe;
};

// Forward declare the main entry functions (stap-generated)
static int
enter_kprobe_probe(struct kprobe *inst,
                   struct pt_regs *regs);
static int
enter_kretprobe_common(struct kretprobe_instance *inst,
                       struct pt_regs *regs, int entry);

// Helper entry functions for kretprobes
static int
enter_kretprobe_probe(struct kretprobe_instance *inst,
                      struct pt_regs *regs)
{
   return enter_kretprobe_common(inst, regs, 0);
}

static int
enter_kretprobe_entry_probe(struct kretprobe_instance *inst,
                            struct pt_regs *regs)
{
   return enter_kretprobe_common(inst, regs, 1);
}

static unsigned long
stapkp_relocate_addr(struct stap_kprobe_probe *skp)
{
   return _stp_kmodule_relocate(skp->module, skp->section, skp->address);
}

static int
stapkp_prepare_kprobe(struct stap_kprobe_probe *skp)
{
   struct kprobe *kp = &skp->kprobe->u.kp;
   unsigned long addr = 0;

// PR28557 Try a pass resolving the address now with the currently
   // known module/section addresses within our own stap-symbols tables.
   addr = stapkp_relocate_addr(skp);
   if (addr != 0) {
           kp->addr = (void*) addr;
   }
   
   // fall back to kallsyms-based or kernel kprobes-delegated symbolic
   // registration
   else if (skp->symbol_name) {
      // If we're doing symbolic name + offset probing (that gets
      // converted to an address), it doesn't really matter if the
      // symbol is in a module and the module isn't loaded right
      // now. The registration will fail, but will get tried again
      // when the module is loaded.
      if (USE_KALLSYMS_ON_EACH_SYMBOL && kp->addr == 0)
	 return 4;
      else if (!USE_KALLSYMS_ON_EACH_SYMBOL) {
        // If we don't have kallsyms_on_each_symbol(), we'll use
        // symbol_name+offset probing and let
        // register_kprobe()/register_kretprobe() call
        // kallsyms_lookup_name() for us. However, on kernels < 3.11,
        // module_kallsyms_lookup_name() (called from
        // kallsyms_lookup_name()) has a bug where it modifies its
        // argument. So, for those kernels we'll workaround the bug by
        // duplicating the string (so we go from read-only memory in the
        // initialized struct data to read-write allocated memory). The
        // memory gets freed when the probe is unregistered.
        //
        // This bug was fixed in kernel 3.11+ by the following commit:
        //
        //   commit 4f6de4d51f4a3ab06a85e91e708cc89a513ef30c
        //      Author: Mathias Krause <minipli@googlemail.com>
        //      Date:   Tue Jul 2 15:35:11 2013 +0930
        //
        //      module: don't modify argument of module_kallsyms_lookup_name()
#if LINUX_VERSION_CODE < KERNEL_VERSION(3,11,0)
        if (kp->symbol_name == NULL)
          kp->symbol_name = kstrdup(skp->symbol_name, STP_ALLOC_FLAGS);
#else
        kp->symbol_name = (typeof(kp->symbol_name))skp->symbol_name;
#endif
        kp->offset = skp->offset;
      }
   }

// NB: success paths need to come here, to set the pre_handler
   kp->pre_handler = &enter_kprobe_probe;

#ifdef __ia64__ // PR6028
   skp->kprobe->dummy.addr = kp->addr;
   skp->kprobe->dummy.pre_handler = NULL;
   skp->kprobe->dummy.symbol_name = kp->symbol_name;
#endif

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30)
   if (!skp->probe->cond_enabled) {
      kp->flags |= KPROBE_FLAG_DISABLED;
      dbug_otf("registering as disabled (kprobe) pidx %zu\n",
               skp->probe->index);
   }
#endif

return 0;
}

static int
stapkp_arch_register_kprobe(struct stap_kprobe_probe *skp)
{
   int ret = 0;
   struct kprobe *kp = &skp->kprobe->u.kp;

#ifndef __ia64__
   ret = register_kprobe(kp);
   if (ret == 0) {
      if (skp->symbol_name)
	 dbug_stapkp("+kprobe %s+%u\n", kp->symbol_name, kp->offset);
      else
	 dbug_stapkp("+kprobe %p\n", kp->addr);
   }
#else // PR6028
   ret = register_kprobe(&skp->kprobe->dummy);
   if (ret == 0) {
      ret = register_kprobe(kp);
      if (ret != 0)
         unregister_kprobe(&skp->kprobe->dummy);
   }
   dbug_stapkp_cond(ret == 0, "+kprobe %p\n", skp->kprobe->dummy.addr);
   dbug_stapkp_cond(ret == 0, "+kprobe %p\n", kp->addr);
#endif

skp->registered_p = (ret ? 0 : 1);

return ret;
}

static int
stapkp_register_kprobe(struct stap_kprobe_probe *skp)
{
   int ret = stapkp_prepare_kprobe(skp);
   if (ret == 0)
      ret = stapkp_arch_register_kprobe(skp);
   
   dbug_stapkp("stapkp_register_kprobe module %s addr 0x%lx rc %d\n",
               skp->module, (unsigned long)skp->address,
               ret);

return ret;
}

static int
stapkp_prepare_kretprobe(struct stap_kprobe_probe *skp)
{
   struct kretprobe *krp = &skp->kprobe->u.krp;
   unsigned long addr = 0;

if (skp->maxactive_p)
      krp->maxactive = skp->maxactive_val;
   else
      krp->maxactive = KRETACTIVE;

krp->handler = &enter_kretprobe_probe;

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,25)
   if (skp->entry_probe) {
      krp->entry_handler = &enter_kretprobe_entry_probe;
      krp->data_size = skp->saved_longs * sizeof(int64_t) +
                       skp->saved_strings * MAXSTRINGLEN;
   }
#endif

#ifdef __ia64__ // PR6028
   skp->kprobe->dummy.addr = krp->kp.addr;
   skp->kprobe->dummy.pre_handler = NULL;
   skp->kprobe->dummy.symbol_name = krp->kp.symbol_name;
#endif

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30)
   if (!skp->probe->cond_enabled) {
      krp->kp.flags |= KPROBE_FLAG_DISABLED;
      dbug_otf("registering as disabled (kretprobe) pidx %zu\n",
               skp->probe->index);
   }
#endif

return 0;
}

static int
stapkp_arch_register_kretprobe(struct stap_kprobe_probe *skp)
{
   int ret = 0;
   struct kretprobe *krp = &skp->kprobe->u.krp;

#ifndef __ia64__
   ret = register_kretprobe(krp);
   dbug_stapkp_cond(ret == 0, "+kretprobe %p\n", krp->kp.addr);
#else // PR6028
   ret = register_kprobe(&skp->kprobe->dummy);
   if (ret == 0) {
      ret = register_kretprobe(krp);
      if (ret != 0)
         unregister_kprobe(&skp->kprobe->dummy);
   }
   dbug_stapkp_cond(ret == 0, "+kprobe %p\n", skp->kprobe->dummy.addr);
   dbug_stapkp_cond(ret == 0, "+kretprobe %p\n", krp->kp.addr);
#endif

skp->registered_p = (ret ? 0 : 1);

return ret;
}

static int
stapkp_register_kretprobe(struct stap_kprobe_probe *skp)
{
   int ret = stapkp_prepare_kretprobe(skp);
   if (ret == 0)
      ret = stapkp_arch_register_kretprobe(skp);
   return ret;
}

static int
stapkp_register_probe(struct stap_kprobe_probe *skp)
{
   dbug_stapkp("stapkp_register_probe module %s addr 0x%lx reg %d\n",
               skp->module, (unsigned long)skp->address,
               skp->registered_p);

if (skp->registered_p)
      return 0;

return skp->return_p ? stapkp_register_kretprobe(skp)
                        : stapkp_register_kprobe(skp);
}

static void
stapkp_add_missed(struct stap_kprobe_probe *skp)
{
   if (skp->return_p) {

struct kretprobe *krp = &skp->kprobe->u.krp;

atomic_add(krp->nmissed, skipped_count());
#ifdef STP_TIMING
      if (krp->nmissed)
         _stp_warn ("Skipped due to missed kretprobe/1 on '%s': %d\n",
                    skp->probe->pp, krp->nmissed);
#endif

atomic_add(krp->kp.nmissed, skipped_count());
#ifdef STP_TIMING
      if (krp->kp.nmissed)
         _stp_warn ("Skipped due to missed kretprobe/2 on '%s': %lu\n",
                    skp->probe->pp, krp->kp.nmissed);
#endif

} else {

struct kprobe *kp = &skp->kprobe->u.kp;

atomic_add (kp->nmissed, skipped_count());
#ifdef STP_TIMING
      if (kp->nmissed)
         _stp_warn ("Skipped due to missed kprobe on '%s': %lu\n",
                    skp->probe->pp, kp->nmissed);
#endif
   }
}

static void
stapkp_unregister_probe(struct stap_kprobe_probe *skp)
{
   struct stap_kprobe *sk = skp->kprobe;

if (!skp->registered_p)
      return;

if (skp->return_p) {
      unregister_kretprobe (&sk->u.krp);
      if (skp->symbol_name)
	 dbug_stapkp("-kretprobe %s:%d\n", sk->u.krp.kp.symbol_name,
		     sk->u.krp.kp.offset);
      else
	 dbug_stapkp("-kretprobe %p\n", sk->u.krp.kp.addr);
   } else {
      unregister_kprobe (&sk->u.kp);
      if (skp->symbol_name)
	 dbug_stapkp("-kprobe %s:%u\n", sk->u.kp.symbol_name,
		     sk->u.kp.offset);
      else
	 dbug_stapkp("-kprobe %p\n", sk->u.kp.addr);
   }

#if defined(__ia64__)
   unregister_kprobe (&sk->dummy);
   dbug_stapkp("-kprobe %p\n", sk->dummy.addr);
#endif

skp->registered_p = 0;

stapkp_add_missed(skp);

#if LINUX_VERSION_CODE < KERNEL_VERSION(3,11,0)
   if (skp->symbol_name != NULL) {
      if (skp->return_p) {
	 if (sk->u.krp.kp.symbol_name != NULL)
	    kfree(sk->u.krp.kp.symbol_name);
      }
      else {
	 if (sk->u.kp.symbol_name != NULL)
	    kfree(sk->u.kp.symbol_name);
      }
   }
#endif

// PR16861: kprobes may have left some things in the k[ret]probe struct.
   // Let's reset it to be sure it's safe for re-use.
   memset(sk, 0, sizeof(struct stap_kprobe));
}

#if defined(STAPCONF_UNREGISTER_KPROBES)

// The actual size is set later on in
// generic_kprobe_derived_probe_group::emit_module_decls().
static void * stap_unreg_kprobes[];

enum collect_type {
   COLLECT_KPROBES,
#if defined(__ia64__)
   COLLECT_DUMMYS,
#endif
   COLLECT_KRETPROBES
};

static size_t
stapkp_collect_registered_probes(struct stap_kprobe_probe *probes,
                                 size_t nprobes, enum collect_type type)
{
   size_t i, j;

j = 0;
   for (i = 0; i < nprobes; i++) {

struct stap_kprobe_probe *skp = &probes[i];
      struct stap_kprobe *sk = skp->kprobe;

if (!skp->registered_p)
         continue;

if (type == COLLECT_KPROBES && !skp->return_p)
         stap_unreg_kprobes[j++] = &sk->u.kp;
      else if (type == COLLECT_KRETPROBES && skp->return_p)
         stap_unreg_kprobes[j++] = &sk->u.krp;
#if defined(__ia64__)
      else if (type == COLLECT_DUMMYS)
         stap_unreg_kprobes[j++] = &sk->dummy;
#endif
   }

return j;
}

static void
stapkp_batch_unregister_probes(struct stap_kprobe_probe *probes,
                               size_t nprobes)
{
   size_t i, n;

n = stapkp_collect_registered_probes(probes,
                                        nprobes, COLLECT_KPROBES);
   unregister_kprobes((struct kprobe **)stap_unreg_kprobes, n);
   dbug_stapkp_cond(n > 0, "-kprobe * %zd\n", n);

n = stapkp_collect_registered_probes(probes,
                                        nprobes, COLLECT_KRETPROBES);
   unregister_kretprobes((struct kretprobe **)stap_unreg_kprobes, n);
   dbug_stapkp_cond(n > 0, "-kretprobe * %zd\n", n);

#ifdef __ia64__
   n = stapkp_collect_registered_probes(probes,
                                        nprobes, COLLECT_DUMMYS);
   unregister_kprobes((struct kprobe **)stap_unreg_kprobes, n);
   dbug_stapkp_cond(n > 0, "-kprobe * %zd\n", n);
#endif

// Now for all of those we just unregistered, we need to update registered_p
   // and account for (and possibly report) missed hits.
   for (i = 0; i < nprobes; i++) {

struct stap_kprobe_probe *skp = &probes[i];

if (!skp->registered_p)
         continue;

skp->registered_p = 0;

stapkp_add_missed(skp);

#if LINUX_VERSION_CODE < KERNEL_VERSION(3,11,0)
      if (skp->symbol_name != NULL) {
	 if (skp->return_p) {
	    if (skp->kprobe->u.krp.kp.symbol_name != NULL)
	       kfree(skp->kprobe->u.krp.kp.symbol_name);
	 }
	 else {
	    if (skp->kprobe->u.kp.symbol_name != NULL)
	       kfree(skp->kprobe->u.kp.symbol_name);
	 }
      }
#endif

// PR16861: kprobes may have left some things in the k[ret]probe struct.
      // Let's reset it to be sure it's safe for re-use.
      memset(skp->kprobe, 0, sizeof(struct stap_kprobe));
   }
}

#endif /* STAPCONF_UNREGISTER_KPROBES */

static void
stapkp_unregister_probes(struct stap_kprobe_probe *probes,
                         size_t nprobes)
{
#if defined(STAPCONF_UNREGISTER_KPROBES)

// Unregister using batch mode
   stapkp_batch_unregister_probes(probes, nprobes);

#else

// We'll have to unregister them one by one
   size_t i;
   for (i = 0; i < nprobes; i++) {

struct stap_kprobe_probe *skp = &probes[i];

if (!skp->registered_p)
         continue;

stapkp_unregister_probe(skp);
   }

#endif
}

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30)

static int
stapkp_enabled(struct stap_kprobe_probe *skp)
{
   if (!skp->registered_p)
      return 0;

return skp->return_p ? !kprobe_disabled(&skp->kprobe->u.krp.kp)
                        : !kprobe_disabled(&skp->kprobe->u.kp);
}

static int
stapkp_should_enable_probe(struct stap_kprobe_probe *skp)
{
   return  skp->registered_p
       && !stapkp_enabled(skp)
       &&  skp->probe->cond_enabled;
}

static int
stapkp_enable_probe(struct stap_kprobe_probe *skp)
{
   int ret = 0;

dbug_otf("enabling (k%sprobe) pidx %zu\n",
            skp->return_p ? "ret" : "", skp->probe->index);

ret = skp->return_p ? enable_kretprobe(&skp->kprobe->u.krp)
                       : enable_kprobe(&skp->kprobe->u.kp);

if (ret != 0) {
      stapkp_unregister_probe(skp);
      dbug_otf("failed to enable (k%sprobe) pidx %zu (rc %d)\n",
               skp->return_p ? "ret" : "", skp->probe->index, ret);
   }

return ret;
}

static int
stapkp_should_disable_probe(struct stap_kprobe_probe *skp)
{
   return  skp->registered_p
       &&  stapkp_enabled(skp)
       && !skp->probe->cond_enabled;
}

static int
stapkp_disable_probe(struct stap_kprobe_probe *skp)
{
   int ret = 0;

dbug_otf("disabling (k%sprobe) pidx %zu\n",
            skp->return_p ? "ret" : "", skp->probe->index);

ret = skp->return_p ? disable_kretprobe(&skp->kprobe->u.krp)
                       : disable_kprobe(&skp->kprobe->u.kp);

if (ret != 0) {
      stapkp_unregister_probe(skp);
      dbug_otf("failed to disable (k%sprobe) pidx %zu (rc %d)\n",
               skp->return_p ? "ret" : "", skp->probe->index, ret);
   }

return ret;
}

static int
stapkp_refresh_probe(struct stap_kprobe_probe *skp)
{
   if (stapkp_should_enable_probe(skp))
      return stapkp_enable_probe(skp);
   if (stapkp_should_disable_probe(skp))
      return stapkp_disable_probe(skp);
   return 0;
}

#endif /* LINUX_VERSION_CODE >= 2.6.30 */

struct stapkp_symbol_data {
   struct stap_kprobe_probe *probes;
   size_t nprobes;			/* number of probes in "probes" */
   size_t probe_max;			/* number of probes to process */
   const char *modname;
};

static int
stapkp_symbol_callback(void *data, const char *name,
		       struct module *mod, unsigned long addr)
{
   struct stapkp_symbol_data *sd = data;
   size_t i;

if ((mod && sd->modname && strcmp(mod->name, sd->modname) != 0)
       || (!mod && sd->modname))
      return 0;

for (i = 0; i < sd->nprobes; i++) {
      struct stap_kprobe_probe *skp = &sd->probes[i];
      int update_addr = 0;

if (! skp->symbol_name)
	 continue;

// If (1) We're probing a module symbol and we're in that module
      // and the names match; or (2) we're probing a symbol in the
      // kernel and the names match, then update the k[ret]probe
      // address.
      if (mod && skp->module && strcmp(mod->name, skp->module) == 0) {
	 char *colon = strchr(skp->symbol_name, ':');

if (colon != NULL && strcmp(name, colon+1) == 0)
	    update_addr = 1;
      }
      else if (!mod && (skp->module == NULL || skp->module[0] == '\0')
	       && strcmp(name, skp->symbol_name) == 0)
	 update_addr = 1;
      if (update_addr) {

if (skp->return_p)
	    skp->kprobe->u.krp.kp.addr = (void *)(addr + skp->offset);
	 else
	    skp->kprobe->u.kp.addr = (void *)(addr + skp->offset);
	 // Note that we could have more than 1 probe at the same
	 // symbol (with the same or differing offsets), so we can't
	 // return here.
	 //
	 // But we can quit if we've processed all the needed probes.
	 --sd->probe_max;
	 if (sd->probe_max == 0)
	    return -1;
      }
   }
   return 0;
}

static int
stapkp_init(struct stap_kprobe_probe *probes,
            size_t nprobes)
{
   size_t i;

if (USE_KALLSYMS_ON_EACH_SYMBOL) {
     // If we have any symbol_name+offset probes, we need to try to
     // convert those into address-based probes.
     size_t probe_max = 0;
     for (i = 0; i < nprobes; i++) {
       struct stap_kprobe_probe *skp = &probes[i];

if (! skp->symbol_name)
	 continue;
       ++probe_max;
     }
     if (probe_max > 0) {
       // Here we're going to try to convert any symbol_name+offset
       // probes into address probes.
       struct stapkp_symbol_data sd;
       dbug_stapkp("looking up %lu probes\n", probe_max);
       sd.probes = probes;
       sd.nprobes = nprobes;
       sd.probe_max = probe_max;
       sd.modname = NULL;
#ifdef STAPCONF_MODULE_MUTEX
       mutex_lock(&module_mutex);
#endif
       preempt_disable();
       kallsyms_on_each_symbol(stapkp_symbol_callback, &sd);
       preempt_enable();
#ifdef STAPCONF_MODULE_MUTEX
       mutex_unlock(&module_mutex);
#endif
       dbug_stapkp("found %lu probes\n", sd.probe_max);
     }
   }

for (i = 0; i < nprobes; i++) {
      struct stap_kprobe_probe *skp = &probes[i];
      int rc = 0;

rc = stapkp_register_probe(skp);
      if (rc == 1) // failed to relocate addr?
         continue; // don't fuss about it, module probably not loaded

// NB: We keep going even if a probe failed to register (PR6749). We only
      // warn about it if it wasn't optional and isn't in a module.
      if (rc && !skp->optional_p
	  && ((skp->module == NULL) || skp->module[0] == '\0'
	      || strcmp(skp->module, "kernel") == 0)) {
	 if (skp->symbol_name)
	    _stp_warn("probe %s (%s+%u) registration error [man warning::pass5] (rc %d)",
		      skp->probe->pp, skp->symbol_name, skp->offset, rc);
	 else
	    _stp_warn("probe %s (address 0x%lx) registration error [man warning::pass5] (rc %d)",
		      skp->probe->pp, stapkp_relocate_addr(skp), rc);
      }
   }

return 0;
}

/* stapkp_refresh is called for two reasons: either a kprobe needs to be
 * enabled/disabled (modname is NULL), or a module has been loaded/unloaded and
 * kprobes need to be registered/unregistered (modname is !NULL). */
static void
stapkp_refresh(const char *modname,
               struct stap_kprobe_probe *probes,
               size_t nprobes)
{
   size_t i;

dbug_stapkp("refresh %lu probes with module %s\n", nprobes, modname ?: "?");

if (USE_KALLSYMS_ON_EACH_SYMBOL) {
     if (modname) {
       size_t probe_max = 0;
       for (i = 0; i < nprobes; i++) {
	 struct stap_kprobe_probe *skp = &probes[i];

// If this probe is in the same module that is being
	 // loaded/unloaded and the probe is symbol_name+offset based
	 // and it isn't registered (so the module must be loaded),
	 // try to convert all probes in the same module to
	 // address-based probes.
	 if (skp->module && strcmp(modname, skp->module) == 0
	     && skp->symbol_name && skp->registered_p == 0)
           ++probe_max;
       }
       if (probe_max > 0) {
	 struct stapkp_symbol_data sd;
	 sd.probes = probes;
	 sd.nprobes = nprobes;
	 sd.probe_max = probe_max;
	 sd.modname = modname;
#ifdef STAPCONF_MODULE_MUTEX
         mutex_lock(&module_mutex);
#endif
	 preempt_disable();
	 kallsyms_on_each_symbol(stapkp_symbol_callback, &sd);
	 preempt_enable();
#ifdef STAPCONF_MODULE_MUTEX
         mutex_unlock(&module_mutex);
#endif
       }
     }
   }

for (i = 0; i < nprobes; i++) {

struct stap_kprobe_probe *skp = &probes[i];

// was this probe's target module loaded/unloaded
      if (modname && skp->module
            && strcmp(modname, skp->module) == 0) {
         int rc;
         unsigned long addr = (! skp->symbol_name
			       ? stapkp_relocate_addr(skp) : 0);

// module being loaded?
         if (skp->registered_p == 0 && (addr != 0 || skp->symbol_name))
            stapkp_register_probe(skp);
         // module/section being unloaded?
         else if (skp->registered_p == 1 && addr == 0)
            stapkp_unregister_probe(skp);

}
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,30)
      else if (stapkp_should_enable_probe(skp)
              || stapkp_should_disable_probe(skp)) {
         stapkp_refresh_probe(skp);
      }
#endif
   }
}

static void
stapkp_exit(struct stap_kprobe_probe *probes,
            size_t nprobes)
{
   stapkp_unregister_probes(probes, nprobes);
}

#endif /* _KPROBES_C_ */

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