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Filename Latest commit message Latest commit date
Josh Poimboeuf 1084eee4dc x86/unwind/orc: Fix unwind_get_return_address_ptr() for inactive tasks
commit 187b96db5ca79423618dfa29a05c438c34f9e1f0 upstream.

Normally, show_trace_log_lvl() scans the stack, looking for text
addresses to print.  In parallel, it unwinds the stack with
unwind_next_frame().  If the stack address matches the pointer returned
by unwind_get_return_address_ptr() for the current frame, the text
address is printed normally without a question mark.  Otherwise it's
considered a breadcrumb (potentially from a previous call path) and it's
printed with a question mark to indicate that the address is unreliable
and typically can be ignored.

Since the following commit:

  f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks")

... for inactive tasks, show_trace_log_lvl() prints *only* unreliable
addresses (prepended with '?').

That happens because, for the first frame of an inactive task,
unwind_get_return_address_ptr() returns the wrong return address
pointer: one word *below* the task stack pointer.  show_trace_log_lvl()
starts scanning at the stack pointer itself, so it never finds the first
'reliable' address, causing only guesses to being printed.

The first frame of an inactive task isn't a normal stack frame.  It's
actually just an instance of 'struct inactive_task_frame' which is left
behind by __switch_to_asm().  Now that this inactive frame is actually
exposed to callers, fix unwind_get_return_address_ptr() to interpret it
properly.

Fixes: f1d9a2abff66 ("x86/unwind/orc: Don't skip the first frame for inactive tasks")
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200522135435.vbxs7umku5pyrdbk@treble
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-27 17:46:50 +02:00
arch x86/unwind/orc: Fix unwind_get_return_address_ptr() for inactive tasks 2020-05-27 17:46:50 +02:00
block iocost: protect iocg->abs_vdebt with iocg->waitq.lock 2020-05-14 07:58:27 +02:00
certs
crypto gcc-10: avoid shadowing standard library 'free()' in crypto 2020-05-20 08:20:29 +02:00
Documentation USB: hub: Revert commit bd0e6c9614 ("usb: hub: try old enumeration scheme first for high speed devices") 2020-04-29 16:33:14 +02:00
drivers rapidio: fix an error in get_user_pages_fast() error handling 2020-05-27 17:46:48 +02:00
fs rxrpc: Fix the excessive initial retransmission timeout 2020-05-27 17:46:48 +02:00
include rxrpc: Fix the excessive initial retransmission timeout 2020-05-27 17:46:48 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel Stop the ad-hoc games with -Wno-maybe-initialized 2020-05-20 08:20:28 +02:00
lib vsprintf: don't obfuscate NULL and error pointers 2020-05-27 17:46:43 +02:00
LICENSES
mm kasan: disable branch tracing for core runtime 2020-05-27 17:46:48 +02:00
net flow_dissector: Drop BPF flow dissector prog ref on netns cleanup 2020-05-27 17:46:49 +02:00
samples vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-29 16:33:14 +02:00
scripts kbuild: Remove debug info from kallsyms linking 2020-05-27 17:46:44 +02:00
security apparmor: Fix aa_label refcnt leak in policy_update 2020-05-27 17:46:42 +02:00
sound ALSA: hda/realtek - Add more fixup entries for Clevo machines 2020-05-27 17:46:40 +02:00
tools KVM: selftests: Fix build for evmcs.h 2020-05-27 17:46:36 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: arm: vgic: Synchronize the whole guest on GIC{D,R}_I{S,C}ACTIVER read 2020-05-20 08:20:04 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 17:22:19 +01:00
Makefile kbuild: avoid concurrency issue in parallel building dtbs and dtbs_check 2020-05-27 17:46:23 +02:00
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.