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Athira Rajeev 60b7ed54a4 powerpc/perf: Fix crash in perf_instruction_pointer() when ppmu is not set
On systems without any specific PMU driver support registered, running
perf record causes Oops.

The relevant portion from call trace:

  BUG: Kernel NULL pointer dereference on read at 0x00000040
  Faulting instruction address: 0xc0021f0c
  Oops: Kernel access of bad area, sig: 11 [#1]
  BE PAGE_SIZE=4K PREEMPT CMPCPRO
  SAF3000 DIE NOTIFICATION
  CPU: 0 PID: 442 Comm: null_syscall Not tainted 5.13.0-rc6-s3k-dev-01645-g7649ee3d2957 #5164
  NIP:  c0021f0c LR: c00e8ad8 CTR: c00d8a5c
  NIP perf_instruction_pointer+0x10/0x60
  LR  perf_prepare_sample+0x344/0x674
  Call Trace:
    perf_prepare_sample+0x7c/0x674 (unreliable)
    perf_event_output_forward+0x3c/0x94
    __perf_event_overflow+0x74/0x14c
    perf_swevent_hrtimer+0xf8/0x170
    __hrtimer_run_queues.constprop.0+0x160/0x318
    hrtimer_interrupt+0x148/0x3b0
    timer_interrupt+0xc4/0x22c
    Decrementer_virt+0xb8/0xbc

During perf record session, perf_instruction_pointer() is called to
capture the sample IP. This function in core-book3s accesses
ppmu->flags. If a platform specific PMU driver is not registered, ppmu
is set to NULL and accessing its members results in a crash. Fix this
crash by checking if ppmu is set.

Fixes: 2ca13a4cc5 ("powerpc/perf: Use regs->nip when SIAR is zero")
Cc: stable@vger.kernel.org # v5.11+
Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1623952506-1431-1-git-send-email-atrajeev@linux.vnet.ibm.com
2021-06-18 16:30:36 +10:00
arch powerpc/perf: Fix crash in perf_instruction_pointer() when ppmu is not set 2021-06-18 16:30:36 +10:00
block block-5.13-2021-05-14 2021-05-15 08:52:30 -07:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
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Documentation powerpc/64s/syscall: Use pt_regs.trap to distinguish syscall ABI difference between sc and scv syscalls 2021-05-21 00:58:03 +10:00
drivers Driver core fixes for 5.13-rc2 2021-05-16 10:13:14 -07:00
fs Merge branch 'akpm' (patches from Andrew) 2021-05-15 09:42:27 -07:00
include Driver core fixes for 5.13-rc2 2021-05-16 10:13:14 -07:00
init Merge branch 'akpm' (patches from Andrew) 2021-05-07 00:34:51 -07:00
ipc ipc/sem.c: spelling fix 2021-05-07 00:26:34 -07:00
kernel Two fixes for timers: 2021-05-16 09:42:13 -07:00
lib kasan: fix unit tests with CONFIG_UBSAN_LOCAL_BOUNDS enabled 2021-05-14 19:41:32 -07:00
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mm mm/ioremap: fix iomap_max_page_shift 2021-05-14 19:41:32 -07:00
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samples Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
scripts Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
security trusted-keys: match tpm_get_ops on all return paths 2021-05-12 22:36:37 +03:00
sound sound fixes for 5.13-rc1 2021-05-07 11:40:18 -07:00
tools powerpc/64s/syscall: Use pt_regs.trap to distinguish syscall ABI difference between sc and scv syscalls 2021-05-21 00:58:03 +10:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt kvm: Cap halt polling at kvm->max_halt_poll_ns 2021-05-07 06:06:22 -04:00
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.mailmap Merge drm/drm-fixes into drm-misc-fixes 2021-05-11 13:35:52 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS libnvdimm fixes for 5.13-rc2 2021-05-15 08:32:51 -07:00
Makefile Linux 5.13-rc2 2021-05-16 15:27:44 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.