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Alex Sverdlin bccb1568ba ARM: 8950/1: ftrace/recordmcount: filter relocation types
commit 927d780ee3 upstream.

Scenario 1, ARMv7
=================

If code in arch/arm/kernel/ftrace.c would operate on mcount() pointer
the following may be generated:

00000230 <prealloc_fixed_plts>:
 230:   b5f8            push    {r3, r4, r5, r6, r7, lr}
 232:   b500            push    {lr}
 234:   f7ff fffe       bl      0 <__gnu_mcount_nc>
                        234: R_ARM_THM_CALL     __gnu_mcount_nc
 238:   f240 0600       movw    r6, #0
                        238: R_ARM_THM_MOVW_ABS_NC      __gnu_mcount_nc
 23c:   f8d0 1180       ldr.w   r1, [r0, #384]  ; 0x180

FTRACE currently is not able to deal with it:

WARNING: CPU: 0 PID: 0 at .../kernel/trace/ftrace.c:1979 ftrace_bug+0x1ad/0x230()
...
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.116-... #1
...
[<c0314e3d>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14)
[<c03115e9>] (show_stack) from [<c051a7f1>] (dump_stack+0x81/0xa8)
[<c051a7f1>] (dump_stack) from [<c0321c5d>] (warn_slowpath_common+0x69/0x90)
[<c0321c5d>] (warn_slowpath_common) from [<c0321cf3>] (warn_slowpath_null+0x17/0x1c)
[<c0321cf3>] (warn_slowpath_null) from [<c038ee9d>] (ftrace_bug+0x1ad/0x230)
[<c038ee9d>] (ftrace_bug) from [<c038f1f9>] (ftrace_process_locs+0x27d/0x444)
[<c038f1f9>] (ftrace_process_locs) from [<c08915bd>] (ftrace_init+0x91/0xe8)
[<c08915bd>] (ftrace_init) from [<c0885a67>] (start_kernel+0x34b/0x358)
[<c0885a67>] (start_kernel) from [<00308095>] (0x308095)
---[ end trace cb88537fdc8fa200 ]---
ftrace failed to modify [<c031266c>] prealloc_fixed_plts+0x8/0x60
 actual: 44:f2:e1:36
ftrace record flags: 0
 (0)   expected tramp: c03143e9

Scenario 2, ARMv4T
==================

ftrace: allocating 14435 entries in 43 pages
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2029 ftrace_bug+0x204/0x310
CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.5 #1
Hardware name: Cirrus Logic EDB9302 Evaluation Board
[<c0010a24>] (unwind_backtrace) from [<c000ecb0>] (show_stack+0x20/0x2c)
[<c000ecb0>] (show_stack) from [<c03c72e8>] (dump_stack+0x20/0x30)
[<c03c72e8>] (dump_stack) from [<c0021c18>] (__warn+0xdc/0x104)
[<c0021c18>] (__warn) from [<c0021d7c>] (warn_slowpath_null+0x4c/0x5c)
[<c0021d7c>] (warn_slowpath_null) from [<c0095360>] (ftrace_bug+0x204/0x310)
[<c0095360>] (ftrace_bug) from [<c04dabac>] (ftrace_init+0x3b4/0x4d4)
[<c04dabac>] (ftrace_init) from [<c04cef4c>] (start_kernel+0x20c/0x410)
[<c04cef4c>] (start_kernel) from [<00000000>] (  (null))
---[ end trace 0506a2f5dae6b341 ]---
ftrace failed to modify
[<c000c350>] perf_trace_sys_exit+0x5c/0xe8
 actual:   1e:ff:2f:e1
Initializing ftrace call sites
ftrace record flags: 0
 (0)
 expected tramp: c000fb24

The analysis for this problem has been already performed previously,
refer to the link below.

Fix the above problems by allowing only selected reloc types in
__mcount_loc. The list itself comes from the legacy recordmcount.pl
script.

Link: https://lore.kernel.org/lkml/56961010.6000806@pengutronix.de/
Cc: stable@vger.kernel.org
Fixes: ed60453fa8 ("ARM: 6511/1: ftrace: add ARM support for C version of recordmcount")
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-29 16:45:27 +01:00
Documentation hwrng: omap3-rom - Fix missing clock by probing with device tree 2020-01-26 10:01:03 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch powerpc/xive: Discard ESB load value when interrupt is invalid 2020-01-29 16:45:26 +01:00
block block: fix memleak of bio integrity data 2020-01-26 10:01:09 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto crypto: algif_skcipher - Use chunksize instead of blocksize 2020-01-17 19:48:46 +01:00
drivers Revert "Input: synaptics-rmi4 - don't increment rmiaddr for SMBus transfers" 2020-01-29 16:45:27 +01:00
fs ceph: hold extra reference to r_parent over life of request 2020-01-29 16:45:24 +01:00
include net: rtnetlink: validate IFLA_MTU attribute in rtnl_create_link() 2020-01-29 16:45:21 +01:00
init mm, debug_pagealloc: don't rely on static keys too early 2020-01-23 08:22:40 +01:00
ipc ipc/sem.c: convert to use built-in RCU list checking 2019-09-25 17:51:41 -07:00
kernel tracing: Fix histogram code when expression has same var as value 2020-01-29 16:45:26 +01:00
lib XArray: Fix xas_find returning too many entries 2020-01-29 16:45:27 +01:00
mm mm/page-writeback.c: avoid potential division by zero in wb_min_max_ratio() 2020-01-23 08:22:41 +01:00
net ipv4: Detect rollover in specific fib table dump 2020-01-29 16:45:24 +01:00
samples samples/bpf: Fix broken xdp_rxq_info due to map order assumptions 2020-01-26 10:00:58 +01:00
scripts ARM: 8950/1: ftrace/recordmcount: filter relocation types 2020-01-29 16:45:27 +01:00
security tomoyo: Suppress RCU warning at list_for_each_entry_rcu(). 2020-01-17 19:49:05 +01:00
sound ALSA: usb-audio: fix sync-ep altsetting sanity check 2020-01-23 08:22:31 +01:00
tools kselftests: cgroup: Avoid the reuse of fd after it is deallocated 2020-01-26 10:01:07 +01:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-09 10:20:00 +01:00
virt KVM: arm/arm64: Properly handle faulting of device mappings 2019-12-31 16:46:24 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: Append missed file to the database 2020-01-17 19:48:28 +01:00
Makefile Linux 5.4.15 2020-01-26 10:01:09 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.