Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 211 insertions, 0 deletions

diff --git a/drivers/rtc/lib.c b/drivers/rtc/lib.c
new file mode 100644
index 000000000..f7051592a
--- /dev/null
+++ b/drivers/rtc/lib.c
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rtc and date/time utility functions
+ *
+ * Copyright (C) 2005-06 Tower Technologies
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * based on arch/arm/common/rtctime.c and other bits
+ *
+ * Author: Cassio Neri <cassio.neri@gmail.com> (rtc_time64_to_tm)
+ */
+
+#include <linux/export.h>
+#include <linux/rtc.h>
+
+static const unsigned char rtc_days_in_month[] = {
+	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+};
+
+static const unsigned short rtc_ydays[2][13] = {
+	/* Normal years */
+	{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
+	/* Leap years */
+	{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
+};
+
+/*
+ * The number of days in the month.
+ */
+int rtc_month_days(unsigned int month, unsigned int year)
+{
+	return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
+}
+EXPORT_SYMBOL(rtc_month_days);
+
+/*
+ * The number of days since January 1. (0 to 365)
+ */
+int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
+{
+	return rtc_ydays[is_leap_year(year)][month] + day - 1;
+}
+EXPORT_SYMBOL(rtc_year_days);
+
+/**
+ * rtc_time64_to_tm - converts time64_t to rtc_time.
+ *
+ * @time:	The number of seconds since 01-01-1970 00:00:00.
+ *		Works for values since at least 1900
+ * @tm:		Pointer to the struct rtc_time.
+ */
+void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
+{
+	int secs;
+
+	u64 u64tmp;
+	u32 u32tmp, udays, century, day_of_century, year_of_century, year,
+		day_of_year, month, day;
+	bool is_Jan_or_Feb, is_leap_year;
+
+	/*
+	 * The time represented by `time` is given in seconds since 1970-01-01
+	 * (UTC). As the division done below might misbehave for negative
+	 * values, we convert it to seconds since 0000-03-01 and then assume it
+	 * will be non-negative.
+	 * Below we do 4 * udays + 3 which should fit into a 32 bit unsigned
+	 * variable. So the latest date this algorithm works for is 1073741823
+	 * days after 0000-03-01 which is in the year 2939805.
+	 */
+	time += (u64)719468 * 86400;
+
+	udays = div_s64_rem(time, 86400, &secs);
+
+	/*
+	 * day of the week, 0000-03-01 was a Wednesday (in the proleptic
+	 * Gregorian calendar)
+	 */
+	tm->tm_wday = (udays + 3) % 7;
+
+	/*
+	 * The following algorithm is, basically, Figure 12 of Neri
+	 * and Schneider [1]. In a few words: it works on the computational
+	 * (fictitious) calendar where the year starts in March, month = 2
+	 * (*), and finishes in February, month = 13. This calendar is
+	 * mathematically convenient because the day of the year does not
+	 * depend on whether the year is leap or not. For instance:
+	 *
+	 * March 1st		0-th day of the year;
+	 * ...
+	 * April 1st		31-st day of the year;
+	 * ...
+	 * January 1st		306-th day of the year; (Important!)
+	 * ...
+	 * February 28th	364-th day of the year;
+	 * February 29th	365-th day of the year (if it exists).
+	 *
+	 * After having worked out the date in the computational calendar
+	 * (using just arithmetics) it's easy to convert it to the
+	 * corresponding date in the Gregorian calendar.
+	 *
+	 * [1] Neri C, Schneider L. Euclidean affine functions and their
+	 *     application to calendar algorithms. Softw Pract Exper.
+	 *     2023;53(4):937-970. doi: 10.1002/spe.3172
+	 *     https://doi.org/10.1002/spe.3172
+	 *
+	 * (*) The numbering of months follows rtc_time more closely and
+	 * thus, is slightly different from [1].
+	 */
+
+	u32tmp		= 4 * udays + 3;
+	century		= u32tmp / 146097;
+	day_of_century	= u32tmp % 146097 / 4;
+
+	u32tmp		= 4 * day_of_century + 3;
+	u64tmp		= 2939745ULL * u32tmp;
+	year_of_century	= upper_32_bits(u64tmp);
+	day_of_year	= lower_32_bits(u64tmp) / 2939745 / 4;
+
+	year		= 100 * century + year_of_century;
+	is_leap_year	= year_of_century != 0 ?
+		year_of_century % 4 == 0 : century % 4 == 0;
+
+	u32tmp		= 2141 * day_of_year + 132377;
+	month		= u32tmp >> 16;
+	day		= ((u16) u32tmp) / 2141;
+
+	/*
+	 * Recall that January 01 is the 306-th day of the year in the
+	 * computational (not Gregorian) calendar.
+	 */
+	is_Jan_or_Feb	= day_of_year >= 306;
+
+	/* Converts to the Gregorian calendar. */
+	year		= year + is_Jan_or_Feb;
+	month		= is_Jan_or_Feb ? month - 12 : month;
+	day		= day + 1;
+
+	day_of_year	= is_Jan_or_Feb ?
+		day_of_year - 306 : day_of_year + 31 + 28 + is_leap_year;
+
+	/* Converts to rtc_time's format. */
+	tm->tm_year	= (int) (year - 1900);
+	tm->tm_mon	= (int) month;
+	tm->tm_mday	= (int) day;
+	tm->tm_yday	= (int) day_of_year + 1;
+
+	tm->tm_hour = secs / 3600;
+	secs -= tm->tm_hour * 3600;
+	tm->tm_min = secs / 60;
+	tm->tm_sec = secs - tm->tm_min * 60;
+
+	tm->tm_isdst = 0;
+}
+EXPORT_SYMBOL(rtc_time64_to_tm);
+
+/*
+ * Does the rtc_time represent a valid date/time?
+ */
+int rtc_valid_tm(struct rtc_time *tm)
+{
+	if (tm->tm_year < 70 ||
+	    tm->tm_year > (INT_MAX - 1900) ||
+	    ((unsigned int)tm->tm_mon) >= 12 ||
+	    tm->tm_mday < 1 ||
+	    tm->tm_mday > rtc_month_days(tm->tm_mon,
+					 ((unsigned int)tm->tm_year + 1900)) ||
+	    ((unsigned int)tm->tm_hour) >= 24 ||
+	    ((unsigned int)tm->tm_min) >= 60 ||
+	    ((unsigned int)tm->tm_sec) >= 60)
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL(rtc_valid_tm);
+
+/*
+ * rtc_tm_to_time64 - Converts rtc_time to time64_t.
+ * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
+ */
+time64_t rtc_tm_to_time64(struct rtc_time *tm)
+{
+	return mktime64(((unsigned int)tm->tm_year + 1900), tm->tm_mon + 1,
+			tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+}
+EXPORT_SYMBOL(rtc_tm_to_time64);
+
+/*
+ * Convert rtc_time to ktime
+ */
+ktime_t rtc_tm_to_ktime(struct rtc_time tm)
+{
+	return ktime_set(rtc_tm_to_time64(&tm), 0);
+}
+EXPORT_SYMBOL_GPL(rtc_tm_to_ktime);
+
+/*
+ * Convert ktime to rtc_time
+ */
+struct rtc_time rtc_ktime_to_tm(ktime_t kt)
+{
+	struct timespec64 ts;
+	struct rtc_time ret;
+
+	ts = ktime_to_timespec64(kt);
+	/* Round up any ns */
+	if (ts.tv_nsec)
+		ts.tv_sec++;
+	rtc_time64_to_tm(ts.tv_sec, &ret);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rtc_ktime_to_tm);