linux

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Thomas Gleixner 7e4a0c17a8 perf/x86: Serialize set_attr_rdpmc()

[ Upstream commit bb9bb45f746b0f9457de9c3fc4da143a6351bdc9 ]

Yue and Xingwei reported a jump label failure. It's caused by the lack of
serialization in set_attr_rdpmc():

CPU0                           CPU1

Assume: x86_pmu.attr_rdpmc == 0

if (val != x86_pmu.attr_rdpmc) {
  if (val == 0)
    ...
  else if (x86_pmu.attr_rdpmc == 0)
    static_branch_dec(&rdpmc_never_available_key);

				if (val != x86_pmu.attr_rdpmc) {
				   if (val == 0)
				      ...
				   else if (x86_pmu.attr_rdpmc == 0)
     FAIL, due to imbalance --->      static_branch_dec(&rdpmc_never_available_key);

The reported BUG() is a consequence of the above and of another bug in the
jump label core code. The core code needs a separate fix, but that cannot
prevent the imbalance problem caused by set_attr_rdpmc().

Prevent this by serializing set_attr_rdpmc() locally.

Fixes: a66734297f78 ("perf/x86: Add /sys/devices/cpu/rdpmc=2 to allow rdpmc for all tasks")
Closes: https://lore.kernel.org/r/CAEkJfYNzfW1vG=ZTMdz_Weoo=RXY1NDunbxnDaLyj8R4kEoE_w@mail.gmail.com
Reported-by: Yue Sun <samsun1006219@gmail.com>
Reported-by: Xingwei Lee <xrivendell7@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20240610124406.359476013@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>

2024-08-03 08:59:37 +02:00

alpha

mseal: wire up mseal syscall

2024-05-23 19:40:26 -07:00

arc

bpf-for-netdev

2024-05-27 16:26:30 -07:00

arm

ARM: Remove address checking for MMUless devices

2024-08-03 08:59:30 +02:00

arm64

arm64: dts: qcom: sm6350: Add missing qcom,non-secure-domain property