ARM: split out processor lookup

Split out the lookup of the processor type and associated error handling
from the rest of setup_processor() - we will need to use this in the
secondary CPU bringup path for big.Little Spectre variant 2 mitigation.

Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
index 2602198..f6df4bb 100644 (file)
--- a/arch/arm/include/asm/cputype.h
+++ b/arch/arm/include/asm/cputype.h
@@ -107,6 +107,7 @@
 #define ARM_CPU_PART_SCORPION          0x510002d0
 
 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/kernel/setup.c b/arch/arm/kernel/setup.c
index fc40a2b..05a4eb6 100644 (file)
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -667,22 +667,29 @@ static void __init smp_build_mpidr_hash(void)
 }
 #endif
 
-static void __init setup_processor(void)
+/*
+ * locate processor in the list of supported processor types.  The linker
+ * builds this table for us from the entries in arch/arm/mm/proc-*.S
+ */
+struct proc_info_list *lookup_processor(u32 midr)
 {
-       struct proc_info_list *list;
+       struct proc_info_list *list = lookup_processor_type(midr);
 
-       /*
-        * locate processor in the list of supported processor
-        * types.  The linker builds this table for us from the
-        * entries in arch/arm/mm/proc-*.S
-        */
-       list = lookup_processor_type(read_cpuid_id());
        if (!list) {
-               pr_err("CPU configuration botched (ID %08x), unable to continue.\n",
-                      read_cpuid_id());
-               while (1);
+               pr_err("CPU%u: configuration botched (ID %08x), CPU halted\n",
+                      smp_processor_id(), midr);
+               while (1)
+               /* can't use cpu_relax() here as it may require MMU setup */;
        }
 
+       return list;
+}
+
+static void __init setup_processor(void)
+{
+       unsigned int midr = read_cpuid_id();
+       struct proc_info_list *list = lookup_processor(midr);
+
        cpu_name = list->cpu_name;
        __cpu_architecture = __get_cpu_architecture();
 
@@ -700,7 +707,7 @@ static void __init setup_processor(void)
 #endif
 
        pr_info("CPU: %s [%08x] revision %d (ARMv%s), cr=%08lx\n",
-               cpu_name, read_cpuid_id(), read_cpuid_id() & 15,
+               list->cpu_name, midr, midr & 15,
                proc_arch[cpu_architecture()], get_cr());
 
        snprintf(init_utsname()->machine, __NEW_UTS_LEN + 1, "%s%c",