[PATCH AUTOSEL 4.9 10/15] ARM: split out processor lookup

Sasha Levin
2018-11-22T19:56:58Z

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

[ Upstream commit 65987a8553061515b5851b472081aedb9837a391 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/include/asm/cputype.h | 1 +
arch/arm/kernel/setup.c | 31 +++++++++++++++++++------------
2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h
index b62eaeb147aa..65db1376f09a 100644
--- a/arch/arm/include/asm/cputype.h
+++ b/arch/arm/include/asm/cputype.h
@@ -98,6 +98,7 @@
#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 f4e54503afa9..8d5c3a118abe 100644
--- 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",
--
2.17.1