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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/print.c (11402B)

/* -*- linux-c -*- 
 * Print Functions
 * Copyright (C) 2007-2018 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 _STAPLINUX_PRINT_C_
#define _STAPLINUX_PRINT_C_

#include "stp_string.h"
#include "print.h"
#include "transport/transport.c"
#include "vsprintf.c"

/** @file print.c
 * Printing Functions.
 */

/** @addtogroup print Print Functions
 * The print buffer is for collecting output to send to the user daemon.
 * This is a per-cpu static buffer.  The buffer is sent when
 * _stp_print_flush() is called.
 *
 * The reason to do this is to allow multiple small prints to be combined then
 * timestamped and sent together to staprun. This is more efficient than sending
 * numerous small packets.
 *
 * This function is called automatically when the print buffer is full.
 * It MUST also be called at the end of every probe that prints something.
 * @{
 */

struct _stp_log {
	unsigned int len; /* Bytes used in the buffer */
	char *buf; /* NB we don't use arrays here to avoid allocating memory
		      on offline CPUs (but still possible ones) */
	atomic_t reentrancy_lock;
};
#include "print_flush.c"

static struct _stp_log *_stp_log_pcpu;

/*
 * An atomic counter is used to synchronize every possible print buffer usage
 * with the _stp_print_cleanup() function. The cleanup function sets the counter
 * to INT_MAX after waiting for everything using the print buffer to finish. We
 * cannot use a lock primitive to implement this because lock_acquire() contains
 * tracepoints and print statements are used both inside and outside of probes.
 * If the lock were only used inside probes, the runtime context would protect
 * us from recursing into the lock_acquire() tracepoints and deadlocking. We
 * instead use _stp_print_ctr as if it were a read-write lock.
 */
static atomic_t _stp_print_ctr = ATOMIC_INIT(0);

/*
 * This disables IRQs to make per-CPU print buffer accesses atomic. There is a
 * reentrancy protection mechanism specifically for NMIs, since they can violate
 * our atomic guarantee. Reentrancy is otherwise allowed within code sections
 * that have the runtime context held (via _stp_runtime_entryfn_get_context()).
 */
static bool _stp_print_trylock_irqsave(unsigned long *flags)
{
	bool context_held = false;
	struct _stp_log *log;

log = per_cpu_ptr(_stp_log_pcpu, raw_smp_processor_id());

/* We have to check log->buf == NULL here since the online
	 * CPUs may change at any time through the CPU hotplug
	 * feature of the kernel. So the current CPU's log->buf could be NULL
	 * if it is a new online CPU. And we cannot allocate new memory from within
	 * this context.
	 */
	if (unlikely(log->buf == NULL))
		return false;

local_irq_save(*flags);
	if (!atomic_add_unless(&_stp_print_ctr, 1, INT_MAX))
		goto irq_restore;

/*
	 * Check the per-CPU reentrancy lock for contention, unless the runtime
	 * context is already held, in which case we already have reentrancy
	 * protection. Otherwise, if the reentrancy lock is contented, that
	 * means we're either inside an NMI that fired while the current CPU was
	 * accessing the log buffer, or something is trying to nest calls to
	 * _stp_print_trylock_irqsave(). Our only choice is to reject the log
	 * access attempt in this case because log buffer corruption and panics
	 * could ensue if we're inside an NMI.
	 */
	if (_stp_runtime_context_trylock()) {
		struct context *c = _stp_runtime_get_context();
		context_held = c && atomic_read(&c->busy);
		_stp_runtime_context_unlock();
	}

/* Fall back onto the reentrancy lock if the context isn't held */
	if (!context_held) {
		if (atomic_cmpxchg(&log->reentrancy_lock, 0, 1))
			goto print_unlock;
	}

return true;

print_unlock:
	atomic_dec(&_stp_print_ctr);
irq_restore:
	local_irq_restore(*flags);
	return false;
}

static void _stp_print_unlock_irqrestore(unsigned long *flags)
{
	bool context_held = false;
	struct _stp_log *log;

if (_stp_runtime_context_trylock()) {
		struct context *c = _stp_runtime_get_context();
		context_held = c && atomic_read(&c->busy);
		_stp_runtime_context_unlock();
	}

if (!context_held) {
		log = per_cpu_ptr(_stp_log_pcpu, raw_smp_processor_id());
		atomic_set(&log->reentrancy_lock, 0);
	}

atomic_dec(&_stp_print_ctr);
	local_irq_restore(*flags);
}

/* create percpu print and io buffers */
static int _stp_print_init (void)
{
	unsigned int cpu;

/* _stp_alloc_percpu() always zero-fills the allocated percpu memory
	 * since the kernel's __alloc_percpu() always does that.
	 */
	_stp_log_pcpu = _stp_alloc_percpu(sizeof(*_stp_log_pcpu));
	if (!_stp_log_pcpu)
		return -ENOMEM;

/* We don't use for_aech_possible_cpu() here since the number of possible
	 * CPUs may be very large even though there are many fewere online CPUs.
	 * For example, VMWare guests usually have 128 possible CPUs while only
	 * have a few online CPUs. Once the bufs were allocated for
	 * online CPUs at this point, we will discard any printing operations on
	 * any future online CPUs dynamically added through the kernel's CPU
	 * hotplug feature. Memory allocations of the bufs can only happen right
	 * here.
	 */
	for_each_online_cpu(cpu) {
		struct _stp_log *log = per_cpu_ptr(_stp_log_pcpu, cpu);

log->reentrancy_lock = (atomic_t)ATOMIC_INIT(0);
		log->buf = _stp_vzalloc_node(STP_BUFFER_SIZE, cpu_to_node(cpu));
		if (unlikely(log->buf == NULL)) {
			_stp_error ("print log buf (size %lu per cpu) allocation failed",
				    (unsigned long) STP_BUFFER_SIZE);
			return -ENOMEM;
		}
	}
	return 0;
}

static void _stp_print_cleanup (void)
{
	unsigned int cpu;

/* Wait for the loggers to finish modifying the print buffers */
	while (atomic_cmpxchg(&_stp_print_ctr, 0, INT_MAX))
		cpu_relax();

/* NB We cannot use the for_each_online_cpu() here since online
	 * CPUs may get changed on-the-fly through the CPU hotplug feature
	 * of the kernel. We only allocated bufs on original online CPUs
	 * when _stp_print_init() was called. */
	for_each_possible_cpu(cpu) {
		struct _stp_log *log = per_cpu_ptr(_stp_log_pcpu, cpu);

/*
		 * Flush anything that could be left in the print buffer. It is
		 * safe to do this without any kind of synchronization mechanism
		 * because nothing is using this print buffer anymore.
		 */
		if (likely(log->buf)) {
			/* We have to check log->buf != NULL here since the
			 * online CPUs may change at any time through the CPU
			 * hotplug feature of the kernel.
			 */
			__stp_print_flush(log);
			_stp_vfree(log->buf);
			log->buf = NULL;
		}
	}

_stp_free_percpu(_stp_log_pcpu);
}

static inline void _stp_print_flush(void)
{
	struct _stp_log *log;
	unsigned long flags;

if (!_stp_print_trylock_irqsave(&flags))
		return;

log = per_cpu_ptr(_stp_log_pcpu, raw_smp_processor_id());
	__stp_print_flush(log);
	_stp_print_unlock_irqrestore(&flags);
}

#ifndef STP_MAXBINARYARGS
#define STP_MAXBINARYARGS 127
#endif

/** Reserves space in the output buffer for direct I/O. Must be called with
 * _stp_print_trylock_irqsave() held.
 */
static void * _stp_reserve_bytes (int numbytes)
{
	struct _stp_log *log;
	char *ret;

if (unlikely(numbytes == 0 || numbytes > STP_BUFFER_SIZE))
		return NULL;

log = per_cpu_ptr(_stp_log_pcpu, raw_smp_processor_id());
	/* _stp_print_trylock_irqsave already checks log->buf != NULL */

if (unlikely(numbytes > (STP_BUFFER_SIZE - log->len)))
		__stp_print_flush(log);

ret = &log->buf[log->len];
	log->len += numbytes;
	return ret;
}

static void _stp_unreserve_bytes (int numbytes)
{
	struct _stp_log *log;

log = per_cpu_ptr(_stp_log_pcpu, raw_smp_processor_id());

/* We have to check log->buf == NULL here since the online CPUs may
	 * change at any time through the CPU hotplug feature of the kernel.
	 * So the current CPU's log->buf could be NULL if it is a new online
	 * CPU.
	 */
	if (unlikely(log->buf == NULL))
		return;

if (numbytes <= log->len)
		log->len -= numbytes;
}

/** Write 64-bit args directly into the output stream.
 * This function takes a variable number of 64-bit arguments
 * and writes them directly into the output stream.  Marginally faster
 * than doing the same in _stp_vsnprintf().
 * @sa _stp_vsnprintf()
 */
static void _stp_print_binary (int num, ...)
{
	unsigned long flags;
	va_list vargs;
	int i;
	int64_t *args;

if (unlikely(num > STP_MAXBINARYARGS))
		num = STP_MAXBINARYARGS;

if (!_stp_print_trylock_irqsave(&flags))
		return;

args = _stp_reserve_bytes(num * sizeof(int64_t));
	if (args) {
		va_start(vargs, num);
		for (i = 0; i < num; i++)
			args[i] = va_arg(vargs, int64_t);
		va_end(vargs);
	}
	_stp_print_unlock_irqrestore(&flags);
}

/** Print into the print buffer.
 * Like C printf.
 *
 * @sa _stp_print_flush()
 */
static void _stp_printf (const char *fmt, ...)
{
	va_list args;

va_start(args, fmt);
	_stp_vsnprintf(NULL, 0, fmt, args);
	va_end(args);
}

/** Write a string into the print buffer.
 * @param str A C string (char *)
 */

static void _stp_print (const char *str)
{
	struct _stp_log *log;
	unsigned long flags;

if (!_stp_print_trylock_irqsave(&flags))
		return;

log = per_cpu_ptr(_stp_log_pcpu, raw_smp_processor_id());
	while (1) {
		while (log->len < STP_BUFFER_SIZE && *str)
			log->buf[log->len++] = *str++;
		if (likely(!*str))
			break;
		__stp_print_flush(log);
	}
	_stp_print_unlock_irqrestore(&flags);
}

static void _stp_print_char (const char c)
{
	struct _stp_log *log;
	unsigned long flags;

if (!_stp_print_trylock_irqsave(&flags))
		return;

log = per_cpu_ptr(_stp_log_pcpu, raw_smp_processor_id());
	if (unlikely(log->len == STP_BUFFER_SIZE))
		__stp_print_flush(log);
	log->buf[log->len++] = c;
	_stp_print_unlock_irqrestore(&flags);
}

static void _stp_print_kernel_info(char *sname, char *vstr, int ctx, int num_probes)
{
	printk(KERN_DEBUG
               "%s (%s): systemtap: %s, base: %lx"
               ", memory: %ludata/%lutext/%uctx/%lunet/%lualloc kb"
               ", probes: %d"
#if ! STP_PRIVILEGE_CONTAINS (STP_PRIVILEGE, STP_PR_STAPDEV)
               ", unpriv-uid: %d"
#endif
               "\n",
	       THIS_MODULE->name,
	       sname, /* name of source file */
	       vstr,  /* stap version */
#ifdef STAPCONF_MODULE_LAYOUT
	       (unsigned long) THIS_MODULE->core_layout.base,
	       (unsigned long) (THIS_MODULE->core_layout.size - THIS_MODULE->core_layout.text_size)/1024,
	       (unsigned long) (THIS_MODULE->core_layout.text_size)/1024,
#else
#ifndef STAPCONF_GRSECURITY
	       (unsigned long) THIS_MODULE->module_core,
	       (unsigned long) (THIS_MODULE->core_size - THIS_MODULE->core_text_size)/1024,
               (unsigned long) (THIS_MODULE->core_text_size)/1024,
#else
               (unsigned long) THIS_MODULE->module_core_rx,
	       (unsigned long) (THIS_MODULE->core_size_rw - THIS_MODULE->core_size_rx)/1024,
               (unsigned long) (THIS_MODULE->core_size_rx)/1024,
#endif
#endif
	       ctx/1024,
	       _stp_allocated_net_memory/1024,
	       (_stp_allocated_memory - _stp_allocated_net_memory - ctx)/1024,
               /* (un-double-counting net/ctx because they're also stp_alloc'd) */
               num_probes
#if ! STP_PRIVILEGE_CONTAINS (STP_PRIVILEGE, STP_PR_STAPDEV)
               , _stp_uid
#endif
                );
}

/** @} */
#endif /* _STAPLINUX_PRINT_C_ */

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