Revert "arm64: cpuinfo: print info for all CPUs"

It turns out that vendors are relying on the format of /proc/cpuinfo,
and we've even spotted out-of-tree hacks attempting to make it look
identical to the format used by arch/arm/. That means we can't afford to
churn this interface in mainline, so revert the recent reformatting of
the file for arm64 pending discussions on the list to find out what
people actually want.

This reverts commit d7a49086f2.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/setup.c

@@ -78,6 +78,7 @@ unsigned int compat_elf_hwcap2 __read_mostly;
 #endif
 
 static const char *cpu_name;
+static const char *machine_name;
 phys_addr_t __fdt_pointer __initdata;
 
 /*
@@ -309,6 +310,8 @@ static void __init setup_machine_fdt(phys_addr_t dt_phys)
 		while (true)
 			cpu_relax();
 	}
+
+	machine_name = of_flat_dt_get_machine_name();
 }
 
 /*
@@ -447,21 +450,10 @@ static int c_show(struct seq_file *m, void *v)
 {
 	int i;
 
-	/*
-	 * Dump out the common processor features in a single line. Userspace
-	 * should read the hwcaps with getauxval(AT_HWCAP) rather than
-	 * attempting to parse this.
-	 */
-	seq_puts(m, "features\t:");
-	for (i = 0; hwcap_str[i]; i++)
-		if (elf_hwcap & (1 << i))
-			seq_printf(m, " %s", hwcap_str[i]);
-	seq_puts(m, "\n\n");
+	seq_printf(m, "Processor\t: %s rev %d (%s)\n",
+		   cpu_name, read_cpuid_id() & 15, ELF_PLATFORM);
 
 	for_each_online_cpu(i) {
-		struct cpuinfo_arm64 *cpuinfo = &per_cpu(cpu_data, i);
-		u32 midr = cpuinfo->reg_midr;
-
 		/*
 		 * glibc reads /proc/cpuinfo to determine the number of
 		 * online processors, looking for lines beginning with
@@ -470,13 +462,25 @@ static int c_show(struct seq_file *m, void *v)
 #ifdef CONFIG_SMP
 		seq_printf(m, "processor\t: %d\n", i);
 #endif
-		seq_printf(m, "implementer\t: 0x%02x\n",
-			   MIDR_IMPLEMENTOR(midr));
-		seq_printf(m, "variant\t\t: 0x%x\n", MIDR_VARIANT(midr));
-		seq_printf(m, "partnum\t\t: 0x%03x\n", MIDR_PARTNUM(midr));
-		seq_printf(m, "revision\t: 0x%x\n\n", MIDR_REVISION(midr));
 	}
 
+	/* dump out the processor features */
+	seq_puts(m, "Features\t: ");
+
+	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;
 }