Alexey Brodkin 578c60fb4a ARC: perf: Accommodate big-endian CPU ... commit 5effc09c49 upstream. 8-letter strings representing ARC perf events are stores in two 32-bit registers as ASCII characters like that: "IJMP", "IALL", "IJMPTAK" etc. And the same order of bytes in the word is used regardless CPU endianness. Which means in case of big-endian CPU core we need to swap bytes to get the same order as if it was on little-endian CPU. Otherwise we're seeing the following error message on boot: ------------------------->8---------------------- ARC perf : 8 counters (32 bits), 40 conditions, [overflow IRQ support] sysfs: cannot create duplicate filename '/devices/arc_pct/events/pmji' CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.2.18 #3 Stack Trace: arc_unwind_core+0xd4/0xfc dump_stack+0x64/0x80 sysfs_warn_dup+0x46/0x58 sysfs_add_file_mode_ns+0xb2/0x168 create_files+0x70/0x2a0 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1 at kernel/events/core.c:12144 perf_event_sysfs_init+0x70/0xa0 Failed to register pmu: arc_pct, reason -17 Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.2.18 #3 Stack Trace: arc_unwind_core+0xd4/0xfc dump_stack+0x64/0x80 __warn+0x9c/0xd4 warn_slowpath_fmt+0x22/0x2c perf_event_sysfs_init+0x70/0xa0 ---[ end trace a75fb9a9837bd1ec ]--- ------------------------->8---------------------- What happens here we're trying to register more than one raw perf event with the same name "PMJI". Why? Because ARC perf events are 4 to 8 letters and encoded into two 32-bit words. In this particular case we deal with 2 events: * "IJMP____" which counts all jump & branch instructions * "IJMPC___" which counts only conditional jumps & branches Those strings are split in two 32-bit words this way "IJMP" + "____" & "IJMP" + "C___" correspondingly. Now if we read them swapped due to CPU core being big-endian then we read "PMJI" + "____" & "PMJI" + "___C". And since we interpret read array of ASCII letters as a null-terminated string on big-endian CPU we end up with 2 events of the same name "PMJI". Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> Cc: stable@vger.kernel.org Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2019-12-01 09:14:21 +01:00
..
boot	ARC: [plat-hsdk]: Add missing FIFO size entry in GMAC node	2019-06-25 11:36:51 +08:00
configs	arc: hsdk_defconfig: Enable CONFIG_BLK_DEV_RAM	2019-04-20 09:14:59 +02:00
include	ARC: fix build warnings	2019-06-25 11:36:51 +08:00
kernel	ARC: perf: Accommodate big-endian CPU	2019-12-01 09:14:21 +01:00
lib	ARCv2: lib: memcpy: fix doing prefetchw outside of buffer	2019-03-23 14:35:16 +01:00
mm	ARC: fix build warnings	2019-06-25 11:36:51 +08:00
oprofile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
plat-axs10x	ARC: [plat-axs103] Add temporary quirk to reset ethernet IP	2017-10-03 20:36:49 -07:00
plat-eznps	arc: [plat-eznps] fix printk warning in arc/plat-eznps/mtm.c	2018-09-05 09:26:31 +02:00
plat-hsdk	ARCv2: support manual regfile save on interrupts	2019-03-23 14:35:16 +01:00
plat-sim	ARC: [plat-sim] Include this platform unconditionally	2017-08-04 13:49:47 +05:30
plat-tb10x	arc: select GPIOLIB directly	2016-04-26 14:07:59 +02:00
Kbuild
Kconfig	ARCv2: support manual regfile save on interrupts	2019-03-23 14:35:16 +01:00
Kconfig.debug	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
Makefile	ARC: change defconfig defaults to ARCv2	2018-12-08 13:03:39 +01:00