Patch "powerpc/modules: If mprofile-kernel is enabled add it to vermagic" has been added to the 4.9-stable tree

Patch "powerpc/modules: If mprofile-kernel is enabled add it to vermagic" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    powerpc/modules: If mprofile-kernel is enabled add it to vermagic

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-modules-if-mprofile-kernel-is-enabled-add-it-to-vermagic.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Apr  9 17:09:24 CEST 2018
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Wed, 10 May 2017 16:57:49 +1000
Subject: powerpc/modules: If mprofile-kernel is enabled add it to vermagic

From: Michael Ellerman <mpe@ellerman.id.au>


[ Upstream commit 43e24e82f35291d4c1ca78877ce1b20d3aeb78f1 ]

On powerpc we can build the kernel with two different ABIs for mcount(), which
is used by ftrace. Kernels built with one ABI do not know how to load modules
built with the other ABI. The new style ABI is called "mprofile-kernel", for
want of a better name.

Currently if we build a module using the old style ABI, and the kernel with
mprofile-kernel, when we load the module we'll oops something like:

  # insmod autofs4-no-mprofile-kernel.ko
  ftrace-powerpc: Unexpected instruction f8810028 around bl _mcount
  ------------[ cut here ]------------
  WARNING: CPU: 6 PID: 3759 at ../kernel/trace/ftrace.c:2024 ftrace_bug+0x2b8/0x3c0
  CPU: 6 PID: 3759 Comm: insmod Not tainted 4.11.0-rc3-gcc-5.4.1-00017-g5a61ef74f269 #11
  ...
  NIP [c0000000001eaa48] ftrace_bug+0x2b8/0x3c0
  LR [c0000000001eaff8] ftrace_process_locs+0x4a8/0x590
  Call Trace:
    alloc_pages_current+0xc4/0x1d0 (unreliable)
    ftrace_process_locs+0x4a8/0x590
    load_module+0x1c8c/0x28f0
    SyS_finit_module+0x110/0x140
    system_call+0x38/0xfc
  ...
  ftrace failed to modify
  [<d000000002a31024>] 0xd000000002a31024
   actual:   35:65:00:48

We can avoid this by including in the vermagic whether the kernel/module was
built with mprofile-kernel. Which results in:

  # insmod autofs4-pg.ko
  autofs4: version magic
  '4.11.0-rc3-gcc-5.4.1-00017-g5a61ef74f269 SMP mod_unload modversions '
  should be
  '4.11.0-rc3-gcc-5.4.1-00017-g5a61ef74f269-dirty SMP mod_unload modversions mprofile-kernel'
  insmod: ERROR: could not insert module autofs4-pg.ko: Invalid module format

Fixes: 8c50b72a3b4f ("powerpc/ftrace: Add Kconfig & Make glue for mprofile-kernel")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Acked-by: Jessica Yu <jeyu@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/powerpc/include/asm/module.h |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/powerpc/include/asm/module.h
+++ b/arch/powerpc/include/asm/module.h
@@ -14,6 +14,10 @@
 #include <asm-generic/module.h>
 
 
+#ifdef CC_USING_MPROFILE_KERNEL
+#define MODULE_ARCH_VERMAGIC	"mprofile-kernel"
+#endif
+
 #ifndef __powerpc64__
 /*
  * Thanks to Paul M for explaining this.


Patches currently in stable-queue which might be from mpe@ellerman.id.au are

queue-4.9/selftests-powerpc-fix-tm-resched-dscr-test-with-some-compilers.patch
queue-4.9/powerpc-modules-if-mprofile-kernel-is-enabled-add-it-to-vermagic.patch
queue-4.9/powerpc-mm-fix-virt_addr_valid-etc.-on-64-bit-hash.patch
queue-4.9/powerpc-spufs-fix-coredump-of-spu-contexts.patch
queue-4.9/cxl-unlock-on-error-in-probe.patch
queue-4.9/signal-powerpc-document-conflicts-with-si_user-and-sigfpe-and-sigtrap.patch
queue-4.9/powerpc-don-t-clobber-tcr-when-setting-tcr.patch
queue-4.9/powerpc-8xx-fix-mpc8xx_get_irq-return-on-no-irq.patch