Patch "x86/oprofile/ppro: Do not use __this_cpu*() in preemptible context" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    x86/oprofile/ppro: Do not use __this_cpu*() in preemptible context

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:
     x86-oprofile-ppro-do-not-use-__this_cpu-in-preemptible-context.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 a743bbeef27b9176987ec0cb7f906ab0ab52d1da Mon Sep 17 00:00:00 2001
From: Borislav Petkov <bp@suse.de>
Date: Tue, 7 Nov 2017 18:53:07 +0100
Subject: x86/oprofile/ppro: Do not use __this_cpu*() in preemptible context

From: Borislav Petkov <bp@suse.de>

commit a743bbeef27b9176987ec0cb7f906ab0ab52d1da upstream.

The warning below says it all:

  BUG: using __this_cpu_read() in preemptible [00000000] code: swapper/0/1
  caller is __this_cpu_preempt_check
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.14.0-rc8 #4
  Call Trace:
   dump_stack
   check_preemption_disabled
   ? do_early_param
   __this_cpu_preempt_check
   arch_perfmon_init
   op_nmi_init
   ? alloc_pci_root_info
   oprofile_arch_init
   oprofile_init
   do_one_initcall
   ...

These accessors should not have been used in the first place: it is PPro so
no mixed silicon revisions and thus it can simply use boot_cpu_data.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Fix-creation-mandated-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Robert Richter <rric@kernel.org>
Cc: x86@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/oprofile/op_model_ppro.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/oprofile/op_model_ppro.c
+++ b/arch/x86/oprofile/op_model_ppro.c
@@ -212,8 +212,8 @@ static void arch_perfmon_setup_counters(
 	eax.full = cpuid_eax(0xa);
 
 	/* Workaround for BIOS bugs in 6/15. Taken from perfmon2 */
-	if (eax.split.version_id == 0 && __this_cpu_read(cpu_info.x86) == 6 &&
-		__this_cpu_read(cpu_info.x86_model) == 15) {
+	if (eax.split.version_id == 0 && boot_cpu_data.x86 == 6 &&
+	    boot_cpu_data.x86_model == 15) {
 		eax.split.version_id = 2;
 		eax.split.num_counters = 2;
 		eax.split.bit_width = 40;


Patches currently in stable-queue which might be from bp@suse.de are

queue-4.9/edac-amd64-add-x86cpuid-sanity-check-during-init.patch
queue-4.9/edac-amd64-save-and-return-err-code-from-probe_one_instance.patch
queue-4.9/x86-oprofile-ppro-do-not-use-__this_cpu-in-preemptible-context.patch