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James Clark 287e82cf69 coresight: Fix crash when Perf and sysfs modes are used concurrently
Partially revert the change in commit 6148652807 ("coresight: Enable
and disable helper devices adjacent to the path") which changed the bare
call from source_ops(csdev)->enable() to coresight_enable_source() for
Perf sessions. It was missed that coresight_enable_source() is
specifically for the sysfs interface, rather than being a generic call.
This interferes with the sysfs reference counting to cause the following
crash:

  $ perf record -e cs_etm/@tmc_etr0/ -C 0 &
  $ echo 1 > /sys/bus/coresight/devices/tmc_etr0/enable_sink
  $ echo 1 > /sys/bus/coresight/devices/etm0/enable_source
  $ echo 0 > /sys/bus/coresight/devices/etm0/enable_source

  Unable to handle kernel NULL pointer dereference at virtual
  address 00000000000001d0
  Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
  ...
  Call trace:
   etm4_disable+0x54/0x150 [coresight_etm4x]
   coresight_disable_source+0x6c/0x98 [coresight]
   coresight_disable+0x74/0x1c0 [coresight]
   enable_source_store+0x88/0xa0 [coresight]
   dev_attr_store+0x20/0x40
   sysfs_kf_write+0x4c/0x68
   kernfs_fop_write_iter+0x120/0x1b8
   vfs_write+0x2dc/0x3b0
   ksys_write+0x70/0x108
   __arm64_sys_write+0x24/0x38
   invoke_syscall+0x50/0x128
   el0_svc_common.constprop.0+0x104/0x130
   do_el0_svc+0x40/0xb8
   el0_svc+0x2c/0xb8
   el0t_64_sync_handler+0xc0/0xc8
   el0t_64_sync+0x1a4/0x1a8
  Code: d53cd042 91002000 b9402a81 b8626800 (f940ead5)
  ---[ end trace 0000000000000000 ]---

This commit linked below also fixes the issue, but has unlocked updates
to the mode which could potentially race. So until we come up with a
more complete solution that takes all locking and interaction between
both modes into account, just revert back to the old behavior for Perf.

Reported-by: Junhao He <hejunhao3@huawei.com>
Closes: https://lore.kernel.org/linux-arm-kernel/20230921132904.60996-1-hejunhao3@huawei.com/
Fixes: 6148652807 ("coresight: Enable and disable helper devices adjacent to the path")
Tested-by: Junhao He <hejunhao3@huawei.com>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20231006131452.646721-1-james.clark@arm.com
2023-11-13 09:40:28 +00:00
arch parisc architecture fixes for kernel v6.7-rc1 (part 2): 2023-11-12 11:05:31 -08:00
block blk-core: use pr_warn_ratelimited() in bio_check_ro() 2023-11-07 08:15:23 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression in ahash and hides the Kconfig sub-options for the jitter RNG. 2023-11-09 17:04:58 -08:00
Documentation Probes fixes for v6.7-rc1: 2023-11-10 16:35:04 -08:00
drivers coresight: Fix crash when Perf and sysfs modes are used concurrently 2023-11-13 09:40:28 +00:00
fs Sixteen smb3/cifs client fixes 2023-11-11 17:17:22 -08:00
include Probes fixes for v6.7-rc1: 2023-11-10 16:35:04 -08:00
init As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
io_uring io_uring: do not clamp read length for multishot read 2023-11-06 13:41:58 -07:00
ipc Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
kernel Probes fixes for v6.7-rc1: 2023-11-10 16:35:04 -08:00
lib lib: test_objpool: make global variables static 2023-11-10 19:59:04 +09:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm memblock: report failures when memblock_can_resize is not set 2023-11-08 09:40:13 -08:00
net Including fixes from netfilter and bpf. 2023-11-09 17:09:35 -08:00
rust Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
samples Landlock updates for v6.7-rc1 2023-11-03 09:28:53 -10:00
scripts Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
security + Features 2023-11-03 09:48:17 -10:00
sound sound fixes for 6.7-rc1 2023-11-10 11:57:51 -08:00
tools LoongArch changes for v6.7 2023-11-12 10:58:08 -08:00
usr arch: Remove Itanium (IA-64) architecture 2023-09-11 08:13:17 +00:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: generate kernel.spec in rpmbuild/SPECS/ 2023-10-03 20:49:09 +09:00
.mailmap As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS - removed AR7 platform support 2023-11-10 09:19:46 -08:00
Makefile Linux 6.7-rc1 2023-11-12 16:19:07 -08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.