[PATCHv3 3/5] arm64: cpuinfo: print info for all CPUs

[Mark Rutland]

Currently reading /proc/cpuinfo will result in information being read
out of the MIDR_EL1 of the current CPU, and the information is not
associated with any particular logical CPU number.

This is problematic for systems with heterogeneous CPUs (i.e.
big.LITTLE) where fields will vary across CPUs, and the output will
differ depending on the executing CPU.

This patch reorganises the code responsible for /proc/cpuinfo to print
information per-cpu. As hwcaps are expected to be identical across all
CPUs, this information is printed once.

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
---
 arch/arm64/kernel/setup.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index edb146d..b00b7a3 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -448,20 +448,30 @@ static const char *hwcap_str[] = {
 
 static int c_show(struct seq_file *m, void *v)
 {
-	int i;
+	int c, i;
 
-	seq_printf(m, "Processor\t: %s rev %d (%s)\n",
-		   cpu_name, read_cpuid_id() & 15, ELF_PLATFORM);
+	for_each_online_cpu(c) {
+		struct cpuinfo_arm64 *cpuinfo = &per_cpu(cpu_data, c);
+		u32 midr = cpuinfo->reg_midr;
 
-	for_each_online_cpu(i) {
 		/*
 		 * glibc reads /proc/cpuinfo to determine the number of
 		 * online processors, looking for lines beginning with
 		 * "processor".  Give glibc what it expects.
 		 */
 #ifdef CONFIG_SMP
-		seq_printf(m, "processor\t: %d\n", i);
+		seq_printf(m, "processor\t: %d\n", c);
 #endif
+		seq_printf(m, "Type\t\t: %s rev %d (%s)\n",
+			   cpu_name, MIDR_REVISION(midr), ELF_PLATFORM);
+		seq_printf(m, "CPU implementer\t: 0x%02x\n",
+			   MIDR_IMPLEMENTOR(midr));
+		seq_printf(m, "CPU architecture: AArch64\n");
+		seq_printf(m, "CPU variant\t: 0x%x\n", MIDR_VARIANT(midr));
+		seq_printf(m, "CPU part\t: 0x%03x\n", MIDR_PARTNUM(midr));
+		seq_printf(m, "CPU revision\t: %d\n", MIDR_REVISION(midr));
+
+		seq_puts(m, "\n");
 	}
 
 	/* dump out the processor features */
@@ -470,17 +480,8 @@ static int c_show(struct seq_file *m, void *v)
 	for (i = 0; hwcap_str[i]; i++)
 		if (elf_hwcap & (1 << i))
 			seq_printf(m, "%s ", hwcap_str[i]);
-
-	seq_printf(m, "\nCPU implementer\t: 0x%02x\n", read_cpuid_id() >> 24);
-	seq_printf(m, "CPU architecture: AArch64\n");
-	seq_printf(m, "CPU variant\t: 0x%x\n", (read_cpuid_id() >> 20) & 15);
-	seq_printf(m, "CPU part\t: 0x%03x\n", (read_cpuid_id() >> 4) & 0xfff);
-	seq_printf(m, "CPU revision\t: %d\n", read_cpuid_id() & 15);
-
 	seq_puts(m, "\n");
 
-	seq_printf(m, "Hardware\t: %s\n", machine_name);
-
 	return 0;
 }
 
-- 
1.9.1