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Subject[PATCH 4.4 55/56] x86/oprofile/ppro: Do not use __this_cpu*() in preemptible context
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

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;

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