The following commit has been merged into the x86/entry branch of tip:
Commit-ID: 14d3b376b6c3f66d62559d457d32edf565472163
Gitweb: https://git.kernel.org/tip/14d3b376b6c3f66d62559d457d32edf565472163
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Wed, 03 Jun 2020 13:32:48 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 15 Jun 2020 14:10:09 +02:00
x86/entry, cpumask: Provide non-instrumented variant of cpu_is_offline()
vmlinux.o: warning: objtool: exc_nmi()+0x12: call to cpumask_test_cpu.constprop.0() leaves .noinstr.text section
vmlinux.o: warning: objtool: mce_check_crashing_cpu()+0x12: call to cpumask_test_cpu.constprop.0()leaves .noinstr.text section
cpumask_test_cpu()
test_bit()
instrument_atomic_read()
arch_test_bit()
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/include/asm/cpumask.h | 18 ++++++++++++++++++
arch/x86/kernel/cpu/mce/core.c | 2 +-
arch/x86/kernel/nmi.c | 2 +-
3 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/cpumask.h b/arch/x86/include/asm/cpumask.h
index 6722ffc..3afa990 100644
--- a/arch/x86/include/asm/cpumask.h
+++ b/arch/x86/include/asm/cpumask.h
@@ -11,5 +11,23 @@ extern cpumask_var_t cpu_sibling_setup_mask;
extern void setup_cpu_local_masks(void);
+/*
+ * NMI and MCE exceptions need cpu_is_offline() _really_ early,
+ * provide an arch_ special for them to avoid instrumentation.
+ */
+#if NR_CPUS > 1
+static __always_inline bool arch_cpu_online(int cpu)
+{
+ return arch_test_bit(cpu, cpumask_bits(cpu_online_mask));
+}
+#else
+static __always_inline bool arch_cpu_online(int cpu)
+{
+ return cpu == 0;
+}
+#endif
+
+#define arch_cpu_is_offline(cpu) unlikely(!arch_cpu_online(cpu))
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_CPUMASK_H */
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index ce9120c..fbe89a9 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1083,7 +1083,7 @@ static noinstr bool mce_check_crashing_cpu(void)
{
unsigned int cpu = smp_processor_id();
- if (cpu_is_offline(cpu) ||
+ if (arch_cpu_is_offline(cpu) ||
(crashing_cpu != -1 && crashing_cpu != cpu)) {
u64 mcgstatus;
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 2de365f..d7c5e44 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -478,7 +478,7 @@ static DEFINE_PER_CPU(unsigned long, nmi_dr7);
DEFINE_IDTENTRY_RAW(exc_nmi)
{
- if (IS_ENABLED(CONFIG_SMP) && cpu_is_offline(smp_processor_id()))
+ if (IS_ENABLED(CONFIG_SMP) && arch_cpu_is_offline(smp_processor_id()))
return;
if (this_cpu_read(nmi_state) != NMI_NOT_RUNNING) {
|