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Conversion of dates before 1970 is still relevant today because these
dates are reused on some hardwares to store dates bigger than the
maximal date that is representable in the device's native format.
This prominently and very soon affects the hardware covered by the
rtc-mt6397 driver that can only natively store dates in the interval
1900-01-01 up to 2027-12-31. So to store the date 2028-01-01 00:00:00
to such a device, rtc_time64_to_tm() must do the right thing for
time=-2208988800.
Signed-off-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20250428-enable-rtc-v4-1-2b2f7e3f9349@baylibre.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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The current implementation of rtc_time64_to_tm() contains unnecessary
loops, branches and look-up tables. The new one uses an arithmetic-based
algorithm appeared in [1] and is approximately 4.3 times faster (YMMV).
The drawback is that the new code isn't intuitive and contains many 'magic
numbers' (not unusual for this type of algorithm). However, [1] justifies
all those numbers and, given this function's history, the code is unlikely
to need much maintenance, if any at all.
Add a KUnit test case that checks every day in a 160,000 years interval
starting on 1970-01-01 against the expected result. Add a new config
RTC_LIB_KUNIT_TEST symbol to give the option to run this test suite.
[1] Neri, Schneider, "Euclidean Affine Functions and Applications to
Calendar Algorithms". https://arxiv.org/abs/2102.06959
Signed-off-by: Cassio Neri <cassio.neri@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210624201343.85441-1-cassio.neri@gmail.com
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When setting rtc alarm (RTC_WKALM_SET), the tm_year is not checked if it
is in suiteable range. Use INT_MAX - 1900 to check it.
UBSAN: Undefined behaviour in drivers/rtc/rtc-lib.c:119:30
signed integer overflow:
2147483647 + 1900 cannot be represented in type 'int'
CPU: 1 PID: 20994 Comm: syz-executor0 Not tainted 4.19.18-514.55.6.9.x86_64
+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1
04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
ubsan_epilogue+0xe/0x81 lib/ubsan.c:159
handle_overflow+0x193/0x1e2 lib/ubsan.c:190
rtc_tm_to_time64+0x267/0x280 drivers/rtc/rtc-lib.c:119
rtc_tm_to_ktime+0x16/0x70 drivers/rtc/rtc-lib.c:129
rtc_set_alarm+0x1a9/0x2d0 drivers/rtc/interface.c:466
rtc_dev_ioctl+0x6db/0x810 drivers/rtc/rtc-dev.c:380
vfs_ioctl fs/ioctl.c:46 [inline]
do_vfs_ioctl+0x1a5/0x10b0 fs/ioctl.c:690
ksys_ioctl+0x89/0xa0 fs/ioctl.c:705
__do_sys_ioctl fs/ioctl.c:712 [inline]
__se_sys_ioctl fs/ioctl.c:710 [inline]
__x64_sys_ioctl+0x74/0xb0 fs/ioctl.c:710
do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x462589
Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89
f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08
0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8
64 89 01 48
RSP: 002b:00007f5348896c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000072bf00 RCX: 0000000000462589
RDX: 0000000020000000 RSI: 000000004028700f RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f53488976bc
R13: 00000000004bf67e R14: 00000000006f96e0 R15: 00000000ffffffff
==========================================================================
Signed-off-by: Xuefeng Wang <wxf.wang@hisilicon.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Correct trivial checkpatch warnings, mostly whitespace issues and
unbalanced braces.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Use SPDX-License-Identifier instead of a verbose license text. Also fix the
block comment alignment.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Users may call 'ioctl' and pass a very big value on 'tm->tm_year'.
It can be overflowed in 'int' after add 1900.
In function 'rtc_month_days' and 'mktime64', also treated it as an
'unsigned' parameter.
UBSAN: Undefined behaviour in drivers/rtc/rtc-lib.c:103:59
signed integer overflow:
2147483647 + 1900 cannot be represented in type 'int'
UBSAN: Undefined behaviour in drivers/rtc/rtc-lib.c:119:30
signed integer overflow:
2147483647 + 1900 cannot be represented in type 'int'
So, covert it to 'unsigned' explicitly.
Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Rename core files so there is a clearer separation between the RTC core and
the RTC drivers.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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