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authorAlexey Brodkin <Alexey.Brodkin@synopsys.com>2019-10-22 17:04:11 +0300
committerVineet Gupta <vgupta@synopsys.com>2019-10-22 09:59:43 -0700
commit5effc09c4907901f0e71e68e5f2e14211d9a203f (patch)
tree03d7a09206f29a86a758f6200160f233e90a4702 /arch/arc
parentab563bf54a4d08cb59e7d7bcd419f7e8558a4964 (diff)
downloadlinux-5effc09c4907901f0e71e68e5f2e14211d9a203f.tar.bz2
ARC: perf: Accommodate big-endian CPU
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>
Diffstat (limited to 'arch/arc')
-rw-r--r--arch/arc/kernel/perf_event.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arc/kernel/perf_event.c b/arch/arc/kernel/perf_event.c
index 861a8aea51f9..661fd842ea97 100644
--- a/arch/arc/kernel/perf_event.c
+++ b/arch/arc/kernel/perf_event.c
@@ -614,8 +614,8 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
/* loop thru all available h/w condition indexes */
for (i = 0; i < cc_bcr.c; i++) {
write_aux_reg(ARC_REG_CC_INDEX, i);
- cc_name.indiv.word0 = read_aux_reg(ARC_REG_CC_NAME0);
- cc_name.indiv.word1 = read_aux_reg(ARC_REG_CC_NAME1);
+ cc_name.indiv.word0 = le32_to_cpu(read_aux_reg(ARC_REG_CC_NAME0));
+ cc_name.indiv.word1 = le32_to_cpu(read_aux_reg(ARC_REG_CC_NAME1));
arc_pmu_map_hw_event(i, cc_name.str);
arc_pmu_add_raw_event_attr(i, cc_name.str);