Merge branch 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm

Pull ARM spectre updates from Russell King:
 "These are the currently known final bits that resolve the Spectre
  issues. big.Little systems used to be sufficiently identical in that
  there were no differences between individual CPUs in the system that
  mattered to the kernel. With the advent of the Spectre problem, the
  CPUs now have differences in how the workaround is applied.

  As a result of previous Spectre patches, these systems ended up
  reporting quite a lot of:

     "CPUx: Spectre v2: incorrect context switching function, system vulnerable"

  messages due to the action of the big.Little switcher causing the CPUs
  to be re-initialised regularly. This series resolves that issue by
  making the CPU vtable unique to each CPU.

  However, since this is used very early, before per-cpu is setup,
  per-cpu can't be used. We also have a problem that two of the methods
  are not called from preempt-safe paths, but thankfully these remain
  identical between all CPUs in the system. To make sure, we validate
  that these are identical during boot"

* 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: spectre-v2: per-CPU vtables to work around big.Little systems
  ARM: add PROC_VTABLE and PROC_TABLE macros
  ARM: clean up per-processor check_bugs method call
  ARM: split out processor lookup
  ARM: make lookup_processor_type() non-__init

2 files changed, 50 insertions, 12 deletions

diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
index 0d289240b6ca..775cac3c02bb 100644
--- a/arch/arm/include/asm/cputype.h
+++ b/arch/arm/include/asm/cputype.h
@@ -111,6 +111,7 @@
 #include <linux/kernel.h>
 
 extern unsigned int processor_id;
+struct proc_info_list *lookup_processor(u32 midr);
 
 #ifdef CONFIG_CPU_CP15
 #define read_cpuid(reg)							\
diff --git a/arch/arm/include/asm/proc-fns.h b/arch/arm/include/asm/proc-fns.h
index e25f4392e1b2..e1b6f280ab08 100644
--- a/arch/arm/include/asm/proc-fns.h
+++ b/arch/arm/include/asm/proc-fns.h
@@ -23,7 +23,7 @@ struct mm_struct;
 /*
  * Don't change this structure - ASM code relies on it.
  */
-extern struct processor {
+struct processor {
 	/* MISC
 	 * get data abort address/flags
 	 */
@@ -79,9 +79,13 @@ extern struct processor {
 	unsigned int suspend_size;
 	void (*do_suspend)(void *);
 	void (*do_resume)(void *);
-} processor;
+};
 
 #ifndef MULTI_CPU
+static inline void init_proc_vtable(const struct processor *p)
+{
+}
+
 extern void cpu_proc_init(void);
 extern void cpu_proc_fin(void);
 extern int cpu_do_idle(void);
@@ -98,17 +102,50 @@ extern void cpu_reset(unsigned long addr, bool hvc) __attribute__((noreturn));
 extern void cpu_do_suspend(void *);
 extern void cpu_do_resume(void *);
 #else
-#define cpu_proc_init			processor._proc_init
-#define cpu_proc_fin			processor._proc_fin
-#define cpu_reset			processor.reset
-#define cpu_do_idle			processor._do_idle
-#define cpu_dcache_clean_area		processor.dcache_clean_area
-#define cpu_set_pte_ext			processor.set_pte_ext
-#define cpu_do_switch_mm		processor.switch_mm
 
-/* These three are private to arch/arm/kernel/suspend.c */
-#define cpu_do_suspend			processor.do_suspend
-#define cpu_do_resume			processor.do_resume
+extern struct processor processor;
+#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
+#include <linux/smp.h>
+/*
+ * This can't be a per-cpu variable because we need to access it before
+ * per-cpu has been initialised.  We have a couple of functions that are
+ * called in a pre-emptible context, and so can't use smp_processor_id()
+ * there, hence PROC_TABLE().  We insist in init_proc_vtable() that the
+ * function pointers for these are identical across all CPUs.
+ */
+extern struct processor *cpu_vtable[];
+#define PROC_VTABLE(f)			cpu_vtable[smp_processor_id()]->f
+#define PROC_TABLE(f)			cpu_vtable[0]->f
+static inline void init_proc_vtable(const struct processor *p)
+{
+	unsigned int cpu = smp_processor_id();
+	*cpu_vtable[cpu] = *p;
+	WARN_ON_ONCE(cpu_vtable[cpu]->dcache_clean_area !=
+		     cpu_vtable[0]->dcache_clean_area);
+	WARN_ON_ONCE(cpu_vtable[cpu]->set_pte_ext !=
+		     cpu_vtable[0]->set_pte_ext);
+}
+#else
+#define PROC_VTABLE(f)			processor.f
+#define PROC_TABLE(f)			processor.f
+static inline void init_proc_vtable(const struct processor *p)
+{
+	processor = *p;
+}
+#endif
+
+#define cpu_proc_init			PROC_VTABLE(_proc_init)
+#define cpu_check_bugs			PROC_VTABLE(check_bugs)
+#define cpu_proc_fin			PROC_VTABLE(_proc_fin)
+#define cpu_reset			PROC_VTABLE(reset)
+#define cpu_do_idle			PROC_VTABLE(_do_idle)
+#define cpu_dcache_clean_area		PROC_TABLE(dcache_clean_area)
+#define cpu_set_pte_ext			PROC_TABLE(set_pte_ext)
+#define cpu_do_switch_mm		PROC_VTABLE(switch_mm)
+
+/* These two are private to arch/arm/kernel/suspend.c */
+#define cpu_do_suspend			PROC_VTABLE(do_suspend)
+#define cpu_do_resume			PROC_VTABLE(do_resume)
 #endif
 
 extern void cpu_resume(void);