ARM: per-CPU processor vtables

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/include/asm/proc-fns.h b/arch/arm/include/asm/proc-fns.h
index ec13f5311701e73b76789dd6cf0e45b8b569a17f..2b581b1687c54f55eadc0346cae4de41ae01c367 100644 (file)
--- a/arch/arm/include/asm/proc-fns.h
+++ b/arch/arm/include/asm/proc-fns.h
@@ -104,11 +104,25 @@ extern void cpu_do_resume(void *);
 #else
 
 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.
+ */
+extern struct processor *cpu_vtable[];
+#define PROC_VTABLE_FUNC(f)            cpu_vtable[smp_processor_id()]->f
+static inline void init_proc_vtable(const struct processor *p)
+{
+       *cpu_vtable[smp_processor_id()] = *p;
+}
+#else
 #define PROC_VTABLE_FUNC(f)            processor.f
 static inline void init_proc_vtable(const struct processor *p)
 {
        processor = *p;
 }
+#endif
 
 #define cpu_proc_init                  PROC_VTABLE_FUNC(_proc_init)
 #define cpu_check_bugs                 PROC_VTABLE_FUNC(check_bugs)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 4481227d3d98033afd6418ede5923e00cc5180c6..ff3d388efda6392b7d4b0c4ec86d26c124fc36df 100644 (file)
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -115,6 +115,11 @@ EXPORT_SYMBOL(elf_hwcap2);
 
 #ifdef MULTI_CPU
 struct processor processor __ro_after_init;
+#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
+struct processor *cpu_vtable[NR_CPUS] = {
+       [0] = &processor,
+};
+#endif
 #endif
 #ifdef MULTI_TLB
 struct cpu_tlb_fns cpu_tlb __ro_after_init;

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 0978282d5fc27a7c4a5e6b0e274da8bfc4c14c8d..4490c0a8f2be8b45dcc9a4f489bf70653ac32e0f 100644 (file)
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -42,6 +42,7 @@
 #include <asm/mmu_context.h>
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
+#include <asm/procinfo.h>
 #include <asm/processor.h>
 #include <asm/sections.h>
 #include <asm/tlbflush.h>
@@ -102,6 +103,21 @@ static unsigned long get_arch_pgd(pgd_t *pgd)
 #endif
 }
 
+#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
+static int secondary_biglittle_prepare(unsigned int cpu)
+{
+       if (!cpu_vtable[cpu])
+               cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
+
+       return cpu_vtable[cpu] ? 0 : -ENOMEM;
+}
+
+static void secondary_biglittle_init(void)
+{
+       init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
+}
+#endif
+
 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 {
        int ret;
@@ -109,6 +125,12 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
        if (!smp_ops.smp_boot_secondary)
                return -ENOSYS;
 
+#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
+       ret = secondary_biglittle_prepare(cpu);
+       if (ret)
+               return ret;
+#endif
+
        /*
         * We need to tell the secondary core where to find
         * its stack and the page tables.
@@ -359,6 +381,10 @@ asmlinkage void secondary_start_kernel(void)
        struct mm_struct *mm = &init_mm;
        unsigned int cpu;
 
+#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
+       secondary_biglittle_init();
+#endif
+
        /*
         * The identity mapping is uncached (strongly ordered), so
         * switch away from it before attempting any exclusive accesses.

diff --git a/arch/arm/mm/proc-v7-bugs.c b/arch/arm/mm/proc-v7-bugs.c
index 7dca6b4d3bd41d48483164df2a9de117db83b167..9a07916af8dd27dd021781c06451340ce6d03032 100644 (file)
--- a/arch/arm/mm/proc-v7-bugs.c
+++ b/arch/arm/mm/proc-v7-bugs.c
@@ -52,8 +52,6 @@ static void cpu_v7_spectre_init(void)
        case ARM_CPU_PART_CORTEX_A17:
        case ARM_CPU_PART_CORTEX_A73:
        case ARM_CPU_PART_CORTEX_A75:
-               if (cpu_do_switch_mm != cpu_v7_bpiall_switch_mm)
-                       goto bl_error;
                per_cpu(harden_branch_predictor_fn, cpu) =
                        harden_branch_predictor_bpiall;
                spectre_v2_method = "BPIALL";
@@ -61,8 +59,6 @@ static void cpu_v7_spectre_init(void)
 
        case ARM_CPU_PART_CORTEX_A15:
        case ARM_CPU_PART_BRAHMA_B15:
-               if (cpu_do_switch_mm != cpu_v7_iciallu_switch_mm)
-                       goto bl_error;
                per_cpu(harden_branch_predictor_fn, cpu) =
                        harden_branch_predictor_iciallu;
                spectre_v2_method = "ICIALLU";
@@ -88,8 +84,6 @@ static void cpu_v7_spectre_init(void)
                                          ARM_SMCCC_ARCH_WORKAROUND_1, &res);
                        if ((int)res.a0 != 0)
                                break;
-                       if (cpu_do_switch_mm != cpu_v7_hvc_switch_mm && cpu)
-                               goto bl_error;
                        per_cpu(harden_branch_predictor_fn, cpu) =
                                call_hvc_arch_workaround_1;
                        cpu_do_switch_mm = cpu_v7_hvc_switch_mm;
@@ -101,8 +95,6 @@ static void cpu_v7_spectre_init(void)
                                          ARM_SMCCC_ARCH_WORKAROUND_1, &res);
                        if ((int)res.a0 != 0)
                                break;
-                       if (cpu_do_switch_mm != cpu_v7_smc_switch_mm && cpu)
-                               goto bl_error;
                        per_cpu(harden_branch_predictor_fn, cpu) =
                                call_smc_arch_workaround_1;
                        cpu_do_switch_mm = cpu_v7_smc_switch_mm;
@@ -119,11 +111,6 @@ static void cpu_v7_spectre_init(void)
        if (spectre_v2_method)
                pr_info("CPU%u: Spectre v2: using %s workaround\n",
                        smp_processor_id(), spectre_v2_method);
-       return;
-
-bl_error:
-       pr_err("CPU%u: Spectre v2: incorrect context switching function, system vulnerable\n",
-               cpu);
 }
 #else
 static void cpu_v7_spectre_init(void)