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Filename Latest commit message Latest commit date
Will Deacon df0062b27e perf/core: Avoid freeing static PMU contexts when PMU is unregistered
Since commit:

  1fd7e41699 ("perf/core: Remove perf_cpu_context::unique_pmu")

... when a PMU is unregistered then its associated ->pmu_cpu_context is
unconditionally freed. Whilst this is fine for dynamically allocated
context types (i.e. those registered using perf_invalid_context), this
causes a problem for sharing of static contexts such as
perf_{sw,hw}_context, which are used by multiple built-in PMUs and
effectively have a global lifetime.

Whilst testing the ARM SPE driver, which must use perf_sw_context to
support per-task AUX tracing, unregistering the driver as a result of a
module unload resulted in:

 Unable to handle kernel NULL pointer dereference at virtual address 00000038
 Internal error: Oops: 96000004 [#1] PREEMPT SMP
 Modules linked in: [last unloaded: arm_spe_pmu]
 PC is at ctx_resched+0x38/0xe8
 LR is at perf_event_exec+0x20c/0x278
 [...]
 ctx_resched+0x38/0xe8
 perf_event_exec+0x20c/0x278
 setup_new_exec+0x88/0x118
 load_elf_binary+0x26c/0x109c
 search_binary_handler+0x90/0x298
 do_execveat_common.isra.14+0x540/0x618
 SyS_execve+0x38/0x48

since the software context has been freed and the ctx.pmu->pmu_disable_count
field has been set to NULL.

This patch fixes the problem by avoiding the freeing of static PMU contexts
altogether. Whilst the sharing of dynamic contexts is questionable, this
actually requires the caller to share their context pointer explicitly
and so the burden is on them to manage the object lifetime.

Reported-by: Kim Phillips <kim.phillips@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 1fd7e41699 ("perf/core: Remove perf_cpu_context::unique_pmu")
Link: http://lkml.kernel.org/r/1507040450-7730-1-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-10 10:06:54 +02:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-05 08:40:09 -07:00
block block: fix a crash caused by wrong API 2017-09-25 08:56:05 -06:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto crypto: af_alg - update correct dst SGL entry 2017-09-20 17:42:42 +08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-05 08:40:09 -07:00
drivers Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2017-10-05 10:28:12 -07:00
firmware firmware: Restore support for built-in firmware 2017-09-16 10:58:48 -07:00
fs Merge branch 'akpm' (patches from Andrew) 2017-10-04 09:30:50 -07:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-05 08:40:09 -07:00
init Merge branch 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-09-14 18:54:01 -07:00
ipc fix a typo in put_compat_shm_info() 2017-09-25 20:41:46 -04:00
kernel perf/core: Avoid freeing static PMU contexts when PMU is unregistered 2017-10-10 10:06:54 +02:00
lib lib/ratelimit.c: use deferred printk() version 2017-10-03 17:54:26 -07:00
mm mm/memory_hotplug: define find_{smallest|biggest}_section_pfn as unsigned long 2017-10-03 17:54:26 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-10-05 08:40:09 -07:00
samples media updates for v4.14-rc1 2017-09-07 12:53:14 -07:00
scripts checkpatch: fix ignoring cover-letter logic 2017-10-03 17:54:26 -07:00
security lsm: fix smack_inode_removexattr and xattr_getsecurity memleak 2017-10-04 18:03:15 +11:00
sound vfs: constify path argument to kernel_read_file_from_path 2017-09-14 20:18:45 -07:00
tools perf/urgent fix: 2017-10-05 20:07:08 +02:00
usr
virt Revert "KVM: Don't accept obviously wrong gsi values via KVM_IRQFD" 2017-09-19 08:37:17 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap Update James Hogan's email address 2017-10-04 17:11:53 -07:00
COPYING
CREDITS selinux/stable-4.14 PR 20170831 2017-09-12 13:21:00 -07:00
Kbuild
Kconfig
MAINTAINERS ARM: SoC fixes for 4.14-rc 2017-10-04 17:16:05 -07:00
Makefile Linux 4.14-rc3 2017-10-01 14:54:54 -07:00
README

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.