--- /dev/null
+From 44b82b7700d05a52cd983799d3ecde1a976b3bed Mon Sep 17 00:00:00 2001
+From: Mark Rutland <mark.rutland@arm.com>
+Date: Fri, 24 Oct 2014 14:56:40 +0100
+Subject: arm64: Fix up /proc/cpuinfo
+
+From: Mark Rutland <mark.rutland@arm.com>
+
+commit 44b82b7700d05a52cd983799d3ecde1a976b3bed upstream.
+
+Commit d7a49086f263164a (arm64: cpuinfo: print info for all CPUs)
+attempted to clean up /proc/cpuinfo, but due to concerns regarding
+further changes was reverted in commit 5e39977edf6500fd (Revert "arm64:
+cpuinfo: print info for all CPUs").
+
+There are two major issues with the arm64 /proc/cpuinfo format
+currently:
+
+* The "Features" line describes (only) the 64-bit hwcaps, which is
+ problematic for some 32-bit applications which attempt to parse it. As
+ the same names are used for analogous ISA features (e.g. aes) despite
+ these generally being architecturally unrelated, it is not possible to
+ simply append the 64-bit and 32-bit hwcaps in a manner that might not
+ be misleading to some applications.
+
+ Various potential solutions have appeared in vendor kernels. Typically
+ the format of the Features line varies depending on whether the task
+ is 32-bit.
+
+* Information is only printed regarding a single CPU. This does not
+ match the ARM format, and does not provide sufficient information in
+ big.LITTLE systems where CPUs are heterogeneous. The CPU information
+ printed is queried from the current CPU's registers, which is racy
+ w.r.t. cross-cpu migration.
+
+This patch attempts to solve these issues. The following changes are
+made:
+
+* When a task with a LINUX32 personality attempts to read /proc/cpuinfo,
+ the "Features" line contains the decoded 32-bit hwcaps, as with the
+ arm port. Otherwise, the decoded 64-bit hwcaps are shown. This aligns
+ with the behaviour of COMPAT_UTS_MACHINE and COMPAT_ELF_PLATFORM. In
+ the absense of compat support, the Features line is empty.
+
+ The set of hwcaps injected into a task's auxval are unaffected.
+
+* Properties are printed per-cpu, as with the ARM port. The per-cpu
+ information is queried from pre-recorded cpu information (as used by
+ the sanity checks).
+
+* As with the previous attempt at fixing up /proc/cpuinfo, the hardware
+ field is removed. The only users so far are 32-bit applications tied
+ to particular boards, so no portable applications should be affected,
+ and this should prevent future tying to particular boards.
+
+The following differences remain:
+
+* No model_name is printed, as this cannot be queried from the hardware
+ and cannot be provided in a stable fashion. Use of the CPU
+ {implementor,variant,part,revision} fields is sufficient to identify a
+ CPU and is portable across arm and arm64.
+
+* The following system-wide properties are not provided, as they are not
+ possible to provide generally. Programs relying on these are already
+ tied to particular (32-bit only) boards:
+ - Hardware
+ - Revision
+ - Serial
+
+No software has yet been identified for which these remaining
+differences are problematic.
+
+Cc: Greg Hackmann <ghackmann@google.com>
+Cc: Ian Campbell <ijc@hellion.org.uk>
+Cc: Serban Constantinescu <serban.constantinescu@arm.com>
+Cc: Will Deacon <will.deacon@arm.com>
+Cc: cross-distro@lists.linaro.org
+Cc: linux-api@vger.kernel.org
+Cc: linux-arm-kernel@lists.infradead.org
+Cc: linux-kernel@vger.kernel.org
+Acked-by: Catalin Marinas <catalin.marinas@arm.com>
+Signed-off-by: Mark Rutland <mark.rutland@arm.com>
+Signed-off-by: Will Deacon <will.deacon@arm.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/arm64/kernel/setup.c | 94 ++++++++++++++++++++++++++++++++++------------
+ 1 file changed, 71 insertions(+), 23 deletions(-)
+
+--- a/arch/arm64/kernel/setup.c
++++ b/arch/arm64/kernel/setup.c
+@@ -43,6 +43,7 @@
+ #include <linux/of_fdt.h>
+ #include <linux/of_platform.h>
+ #include <linux/efi.h>
++#include <linux/personality.h>
+
+ #include <asm/fixmap.h>
+ #include <asm/cpu.h>
+@@ -79,7 +80,6 @@ unsigned int compat_elf_hwcap2 __read_mo
+ #endif
+
+ static const char *cpu_name;
+-static const char *machine_name;
+ phys_addr_t __fdt_pointer __initdata;
+
+ /*
+@@ -311,8 +311,6 @@ static void __init setup_machine_fdt(phy
+ while (true)
+ cpu_relax();
+ }
+-
+- machine_name = of_flat_dt_get_machine_name();
+ }
+
+ /*
+@@ -449,14 +447,50 @@ static const char *hwcap_str[] = {
+ NULL
+ };
+
++#ifdef CONFIG_COMPAT
++static const char *compat_hwcap_str[] = {
++ "swp",
++ "half",
++ "thumb",
++ "26bit",
++ "fastmult",
++ "fpa",
++ "vfp",
++ "edsp",
++ "java",
++ "iwmmxt",
++ "crunch",
++ "thumbee",
++ "neon",
++ "vfpv3",
++ "vfpv3d16",
++ "tls",
++ "vfpv4",
++ "idiva",
++ "idivt",
++ "vfpd32",
++ "lpae",
++ "evtstrm"
++};
++
++static const char *compat_hwcap2_str[] = {
++ "aes",
++ "pmull",
++ "sha1",
++ "sha2",
++ "crc32",
++ NULL
++};
++#endif /* CONFIG_COMPAT */
++
+ static int c_show(struct seq_file *m, void *v)
+ {
+- int i;
+-
+- seq_printf(m, "Processor\t: %s rev %d (%s)\n",
+- cpu_name, read_cpuid_id() & 15, ELF_PLATFORM);
++ int i, j;
+
+ 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
+@@ -465,24 +499,38 @@ static int c_show(struct seq_file *m, vo
+ #ifdef CONFIG_SMP
+ seq_printf(m, "processor\t: %d\n", i);
+ #endif
+- }
+-
+- /* 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");
++ /*
++ * 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, but there's a body of
++ * software which does already (at least for 32-bit).
++ */
++ seq_puts(m, "Features\t:");
++ if (personality(current->personality) == PER_LINUX32) {
++#ifdef CONFIG_COMPAT
++ for (j = 0; compat_hwcap_str[j]; j++)
++ if (compat_elf_hwcap & (1 << j))
++ seq_printf(m, " %s", compat_hwcap_str[j]);
++
++ for (j = 0; compat_hwcap2_str[j]; j++)
++ if (compat_elf_hwcap2 & (1 << j))
++ seq_printf(m, " %s", compat_hwcap2_str[j]);
++#endif /* CONFIG_COMPAT */
++ } else {
++ for (j = 0; hwcap_str[j]; j++)
++ if (elf_hwcap & (1 << j))
++ seq_printf(m, " %s", hwcap_str[j]);
++ }
++ seq_puts(m, "\n");
+
+- seq_printf(m, "Hardware\t: %s\n", machine_name);
++ seq_printf(m, "CPU implementer\t: 0x%02x\n",
++ MIDR_IMPLEMENTOR(midr));
++ seq_printf(m, "CPU architecture: 8\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\n", MIDR_REVISION(midr));
++ }
+
+ return 0;
+ }
projects / thirdparty / kernel / stable-queue.git / commitdiff
