linux-kernel - [PATCH 4.4 68/75] ARM: split out processor lookup

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Date:   Fri,  8 Nov 2019 19:50:25 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linus.walleij@...aro.org, rmk+kernel@...linux.org.uk, Ard Biesheuvel" 
        <ardb@...nel.org>, Julien Thierry <julien.thierry@....com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        "David A. Long" <dave.long@...aro.org>,
        Sasha Levin <sashal@...nel.org>,
        Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH 4.4 68/75] ARM: split out processor lookup

From: Russell King <rmk+kernel@...linux.org.uk>

Commit 65987a8553061515b5851b472081aedb9837a391 upstream.

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@....com>
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: David A. Long <dave.long@...aro.org>
Reviewed-by: Julien Thierry <julien.thierry@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/arm/include/asm/cputype.h |    1 +
 arch/arm/kernel/setup.c        |   31 +++++++++++++++++++------------
 2 files changed, 20 insertions(+), 12 deletions(-)

--- a/arch/arm/include/asm/cputype.h
+++ b/arch/arm/include/asm/cputype.h
@@ -93,6 +93,7 @@
 #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)							\
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -599,22 +599,29 @@ static void __init smp_build_mpidr_hash(
 }
 #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();
 
@@ -632,7 +639,7 @@ 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",