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Naveen N. Rao 80e5302e4b recordmcount: Fix spurious mcount entries on powerpc
An impending change to enable HAVE_C_RECORDMCOUNT on powerpc leads to
warnings such as the following:

  # modprobe kprobe_example
  ftrace-powerpc: Not expected bl: opcode is 3c4c0001
  WARNING: CPU: 0 PID: 227 at kernel/trace/ftrace.c:2001 ftrace_bug+0x90/0x318
  Modules linked in:
  CPU: 0 PID: 227 Comm: modprobe Not tainted 5.2.0-rc6-00678-g1c329100b942 #2
  NIP:  c000000000264318 LR: c00000000025d694 CTR: c000000000f5cd30
  REGS: c000000001f2b7b0 TRAP: 0700   Not tainted  (5.2.0-rc6-00678-g1c329100b942)
  MSR:  900000010282b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]>  CR: 28228222  XER: 00000000
  CFAR: c0000000002642fc IRQMASK: 0
  <snip>
  NIP [c000000000264318] ftrace_bug+0x90/0x318
  LR [c00000000025d694] ftrace_process_locs+0x4f4/0x5e0
  Call Trace:
  [c000000001f2ba40] [0000000000000004] 0x4 (unreliable)
  [c000000001f2bad0] [c00000000025d694] ftrace_process_locs+0x4f4/0x5e0
  [c000000001f2bb90] [c00000000020ff10] load_module+0x25b0/0x30c0
  [c000000001f2bd00] [c000000000210cb0] sys_finit_module+0xc0/0x130
  [c000000001f2be20] [c00000000000bda4] system_call+0x5c/0x70
  Instruction dump:
  419e0018 2f83ffff 419e00bc 2f83ffea 409e00cc 4800001c 0fe00000 3c62ff96
  39000001 39400000 386386d0 480000c4 <0fe00000> 3ce20003 39000001 3c62ff96
  ---[ end trace 4c438d5cebf78381 ]---
  ftrace failed to modify
  [<c0080000012a0008>] 0xc0080000012a0008
   actual:   01:00:4c:3c
  Initializing ftrace call sites
  ftrace record flags: 2000000
   (0)
   expected tramp: c00000000006af4c

Looking at the relocation records in __mcount_loc shows a few spurious
entries:

  RELOCATION RECORDS FOR [__mcount_loc]:
  OFFSET           TYPE              VALUE
  0000000000000000 R_PPC64_ADDR64    .text.unlikely+0x0000000000000008
  0000000000000008 R_PPC64_ADDR64    .text.unlikely+0x0000000000000014
  0000000000000010 R_PPC64_ADDR64    .text.unlikely+0x0000000000000060
  0000000000000018 R_PPC64_ADDR64    .text.unlikely+0x00000000000000b4
  0000000000000020 R_PPC64_ADDR64    .init.text+0x0000000000000008
  0000000000000028 R_PPC64_ADDR64    .init.text+0x0000000000000014

The first entry in each section is incorrect. Looking at the
relocation records, the spurious entries correspond to the
R_PPC64_ENTRY records:

  RELOCATION RECORDS FOR [.text.unlikely]:
  OFFSET           TYPE              VALUE
  0000000000000000 R_PPC64_REL64     .TOC.-0x0000000000000008
  0000000000000008 R_PPC64_ENTRY     *ABS*
  0000000000000014 R_PPC64_REL24     _mcount
  <snip>

The problem is that we are not validating the return value from
get_mcountsym() in sift_rel_mcount(). With this entry, mcountsym is 0,
but Elf_r_sym(relp) also ends up being 0. Fix this by ensuring
mcountsym is valid before processing the entry.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2019-07-01 16:26:54 +10:00
arch powerpc/rtas: retry when cpu offline races with suspend/migration 2019-07-01 16:26:54 +10:00
block blk-mq: fix hang caused by freeze/unfreeze sequence 2019-05-23 10:25:26 -06:00
certs treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 102 2019-05-24 17:39:00 +02:00
Documentation powerpc: Document xive=off option 2019-07-01 14:06:16 +10:00
drivers cxl: no need to check return value of debugfs_create functions 2019-06-19 20:05:08 +10:00
fs Bug fixes (including a regression fix) for ext4. 2019-05-25 15:03:12 -07:00
include ocxl: do not use C++ style comments in uapi header 2019-06-14 15:35:53 +10:00
init treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
ipc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 52 2019-05-24 17:36:42 +02:00
kernel Make the GCC 9 warning for sub struct memset go away. 2019-05-26 13:49:40 -07:00
lib for-linus-20190524 2019-05-24 16:02:14 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 98 2019-05-24 17:37:54 +02:00
net SPDX update for 5.2-rc2, round 2 2019-05-24 14:31:58 -07:00
samples treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
scripts recordmcount: Fix spurious mcount entries on powerpc 2019-07-01 16:26:54 +10:00
security SPDX update for 5.2-rc2, round 2 2019-05-24 14:31:58 -07:00
sound treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 119 2019-05-24 17:39:02 +02:00
tools Merge branch 'fixes' into next 2019-07-01 14:04:39 +10:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt The usual smattering of fixes and tunings that came in too late for the 2019-05-26 13:45:15 -07:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.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 .gitignore: exclude .get_maintainer.ignore and .gitattributes 2019-05-18 11:49:54 +09:00
.mailmap A reasonably busy cycle for docs, including: 2019-05-08 12:42:50 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Char/Misc driver patches for 5.1-rc1 2019-03-06 14:18:59 -08:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS The usual smattering of fixes and tunings that came in too late for the 2019-05-26 13:45:15 -07:00
Makefile Linux 5.2-rc2 2019-05-26 16:49:19 -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.