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[PATCH v4 0/6] arm64: Support for systems without AArch32 state

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  [PATCH v4 0/6] arm64: Support for systems without AArch32 state Suzuki K Poulose <suzuki.poulose@arm.com> - 2016-04-18 11:30 +0200
    [PATCH v4 5/6] arm64: cpufeature: Track 32bit EL0 support Suzuki K Poulose <suzuki.poulose@arm.com> - 2016-04-18 11:30 +0200
    [PATCH v4 6/6] arm64: compat: Check for AArch32 state Suzuki K Poulose <suzuki.poulose@arm.com> - 2016-04-18 11:30 +0200
    [PATCH v4 3/6] arm64: Add helpers for detecting AArch32 support at EL0 Suzuki K Poulose <suzuki.poulose@arm.com> - 2016-04-18 11:30 +0200
    [PATCH v4 2/6] arm64: HWCAP: Split COMPAT HWCAP table entries Suzuki K Poulose <suzuki.poulose@arm.com> - 2016-04-18 11:30 +0200
    [PATCH v4 1/6] arm64: hwcaps: Cleanup naming Suzuki K Poulose <suzuki.poulose@arm.com> - 2016-04-18 11:40 +0200

#1381408 — [PATCH v4 0/6] arm64: Support for systems without AArch32 state

This series add checks to make sure that the AArch32 state is
supported before we process the 32bit ID registers. Also
checks the same for COMPAT binary execution.

Applies on top of 4.6-rc1. The series remains unchanged from V3, except
for :

Changes since V3:
  - s/32bit/32-bit/ for capability name
  - Fold "Add wrapper for personality() syscall" patch to final patch

Changes since V2:
  - Rebased to 4.6-rc1
  - Drop redundant KVM check introduced in V1.

Changes since V1:
  - Prevent changing the personality to PER_LINUX32 by adding
    wrapper for personality() syscall.
  - Add the check to KVM before initialising a AArch32 vcpu
  - Tested on hardware.

Btw, linux32 doesn't complain when the personality() syscall fails to change
to PER_LINUX32. You can verify the personality by running:

 $ cat /proc/cpuinfo
 which would still list the 64bit features for the CPUs.


Suzuki K Poulose (6):
  arm64: hwcaps: Cleanup naming
  arm64: HWCAP: Split COMPAT HWCAP table entries
  arm64: Add helpers for detecting AArch32 support at EL0
  arm64: cpufeature: Check availability of AArch32
  arm64: cpufeature: Track 32bit EL0 support
  arm64: compat: Check for AArch32 state

 arch/arm64/include/asm/cpufeature.h |   15 ++-
 arch/arm64/include/asm/elf.h        |    3 +-
 arch/arm64/include/asm/sysreg.h     |    1 +
 arch/arm64/kernel/cpufeature.c      |  208 ++++++++++++++++++++---------------
 arch/arm64/kernel/cpuinfo.c         |   37 ++++---
 arch/arm64/kernel/sys.c             |   10 ++
 6 files changed, 165 insertions(+), 109 deletions(-)

-- 
1.7.9.5

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#1381411 — [PATCH v4 5/6] arm64: cpufeature: Track 32bit EL0 support

Add cpu_hwcap bit for keeping track of the support for 32bit EL0.

Tested-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 arch/arm64/include/asm/cpufeature.h |    8 +++++++-
 arch/arm64/kernel/cpufeature.c      |    9 +++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 7f64285..ca8fb4b 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -35,8 +35,9 @@
 #define ARM64_ALT_PAN_NOT_UAO			10
 #define ARM64_HAS_VIRT_HOST_EXTN		11
 #define ARM64_WORKAROUND_CAVIUM_27456		12
+#define ARM64_HAS_32BIT_EL0			13
 
-#define ARM64_NCAPS				13
+#define ARM64_NCAPS				14
 
 #ifndef __ASSEMBLY__
 
@@ -192,6 +193,11 @@ static inline bool cpu_supports_mixed_endian_el0(void)
 	return id_aa64mmfr0_mixed_endian_el0(read_cpuid(ID_AA64MMFR0_EL1));
 }
 
+static inline bool system_supports_32bit_el0(void)
+{
+	return cpus_have_cap(ARM64_HAS_32BIT_EL0);
+}
+
 static inline bool system_supports_mixed_endian_el0(void)
 {
 	return id_aa64mmfr0_mixed_endian_el0(read_system_reg(SYS_ID_AA64MMFR0_EL1));
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index cfc0cfd..4cd8f23 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -733,6 +733,15 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.capability = ARM64_HAS_VIRT_HOST_EXTN,
 		.matches = runs_at_el2,
 	},
+	{
+		.desc = "32-bit EL0 Support",
+		.capability = ARM64_HAS_32BIT_EL0,
+		.matches = has_cpuid_feature,
+		.sys_reg = SYS_ID_AA64PFR0_EL1,
+		.sign = FTR_UNSIGNED,
+		.field_pos = ID_AA64PFR0_EL0_SHIFT,
+		.min_field_value = ID_AA64PFR0_EL0_32BIT_64BIT,
+	},
 	{},
 };
 
-- 
1.7.9.5

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#1381412 — [PATCH v4 6/6] arm64: compat: Check for AArch32 state

Make sure we have AArch32 state available for running COMPAT
binaries and also for switching the personality to PER_LINUX32.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
[ Added cap bit, checks for HWCAP, personality ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Yury Norov <ynorov@caviumnetworks.com>
---
 arch/arm64/include/asm/elf.h   |    3 ++-
 arch/arm64/kernel/cpufeature.c |    7 +++++--
 arch/arm64/kernel/sys.c        |   10 ++++++++++
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 24ed037..7a09c48 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -177,7 +177,8 @@ typedef compat_elf_greg_t		compat_elf_gregset_t[COMPAT_ELF_NGREG];
 
 /* AArch32 EABI. */
 #define EF_ARM_EABI_MASK		0xff000000
-#define compat_elf_check_arch(x)	(((x)->e_machine == EM_ARM) && \
+#define compat_elf_check_arch(x)	(system_supports_32bit_el0() && \
+					 ((x)->e_machine == EM_ARM) && \
 					 ((x)->e_flags & EF_ARM_EABI_MASK))
 
 #define compat_start_thread		compat_start_thread
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 4cd8f23..8c46621 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -982,7 +982,8 @@ void verify_local_cpu_capabilities(void)
 
 	verify_local_cpu_features(arm64_features);
 	verify_local_elf_hwcaps(arm64_elf_hwcaps);
-	verify_local_elf_hwcaps(compat_elf_hwcaps);
+	if (system_supports_32bit_el0())
+		verify_local_elf_hwcaps(compat_elf_hwcaps);
 }
 
 static void __init setup_feature_capabilities(void)
@@ -999,7 +1000,9 @@ void __init setup_cpu_features(void)
 	/* Set the CPU feature capabilies */
 	setup_feature_capabilities();
 	setup_elf_hwcaps(arm64_elf_hwcaps);
-	setup_elf_hwcaps(compat_elf_hwcaps);
+
+	if (system_supports_32bit_el0())
+		setup_elf_hwcaps(compat_elf_hwcaps);
 
 	/* Advertise that we have computed the system capabilities */
 	set_sys_caps_initialised();
diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
index 75151aa..26fe8ea 100644
--- a/arch/arm64/kernel/sys.c
+++ b/arch/arm64/kernel/sys.c
@@ -25,6 +25,7 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/syscalls.h>
+#include <asm/cpufeature.h>
 
 asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
 			 unsigned long prot, unsigned long flags,
@@ -36,11 +37,20 @@ asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
 	return sys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
 }
 
+SYSCALL_DEFINE1(arm64_personality, unsigned int, personality)
+{
+	if (personality(personality) == PER_LINUX32 &&
+		!system_supports_32bit_el0())
+		return -EINVAL;
+	return sys_personality(personality);
+}
+
 /*
  * Wrappers to pass the pt_regs argument.
  */
 asmlinkage long sys_rt_sigreturn_wrapper(void);
 #define sys_rt_sigreturn	sys_rt_sigreturn_wrapper
+#define sys_personality		sys_arm64_personality
 
 #undef __SYSCALL
 #define __SYSCALL(nr, sym)	[nr] = sym,
-- 
1.7.9.5

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#1381414 — [PATCH v4 3/6] arm64: Add helpers for detecting AArch32 support at EL0

Adds a helper to extract the support for AArch32 at EL0

Tested-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 arch/arm64/include/asm/cpufeature.h |    7 +++++++
 arch/arm64/include/asm/sysreg.h     |    1 +
 2 files changed, 8 insertions(+)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index b9b6494..7f64285 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -170,6 +170,13 @@ static inline bool id_aa64mmfr0_mixed_endian_el0(u64 mmfr0)
 		cpuid_feature_extract_unsigned_field(mmfr0, ID_AA64MMFR0_BIGENDEL0_SHIFT) == 0x1;
 }
 
+static inline bool id_aa64pfr0_32bit_el0(u64 pfr0)
+{
+	u32 val = cpuid_feature_extract_unsigned_field(pfr0, ID_AA64PFR0_EL0_SHIFT);
+
+	return val == ID_AA64PFR0_EL0_32BIT_64BIT;
+}
+
 void __init setup_cpu_features(void);
 
 void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 1287416..1a5f602 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -115,6 +115,7 @@
 #define ID_AA64PFR0_ASIMD_SUPPORTED	0x0
 #define ID_AA64PFR0_EL1_64BIT_ONLY	0x1
 #define ID_AA64PFR0_EL0_64BIT_ONLY	0x1
+#define ID_AA64PFR0_EL0_32BIT_64BIT	0x2
 
 /* id_aa64mmfr0 */
 #define ID_AA64MMFR0_TGRAN4_SHIFT	28
-- 
1.7.9.5

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#1381416 — [PATCH v4 2/6] arm64: HWCAP: Split COMPAT HWCAP table entries

In order to handle systems which do not support 32bit at EL0,
split the COMPAT HWCAP entries into a separate table which can
be processed, only if the support is available.

Tested-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 arch/arm64/kernel/cpufeature.c |  104 +++++++++++++++++++++-------------------
 1 file changed, 56 insertions(+), 48 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 23b0f15..a067c31 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -751,6 +751,10 @@ static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
 	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_FP_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, HWCAP_FPHP),
 	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 0, CAP_HWCAP, HWCAP_ASIMD),
 	HWCAP_CAP(SYS_ID_AA64PFR0_EL1, ID_AA64PFR0_ASIMD_SHIFT, FTR_SIGNED, 1, CAP_HWCAP, HWCAP_ASIMDHP),
+	{},
+};
+
+static const struct arm64_cpu_capabilities compat_elf_hwcaps[] = {
 #ifdef CONFIG_COMPAT
 	HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_AES_SHIFT, FTR_UNSIGNED, 2, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_PMULL),
 	HWCAP_CAP(SYS_ID_ISAR5_EL1, ID_ISAR5_AES_SHIFT, FTR_UNSIGNED, 1, CAP_COMPAT_HWCAP2, COMPAT_HWCAP2_AES),
@@ -806,28 +810,23 @@ static bool cpus_have_elf_hwcap(const struct arm64_cpu_capabilities *cap)
 	return rc;
 }
 
-static void __init setup_elf_hwcaps(void)
+static void __init setup_elf_hwcaps(const struct arm64_cpu_capabilities *hwcaps)
 {
-	int i;
-	const struct arm64_cpu_capabilities *hwcaps = arm64_elf_hwcaps;
-
-	for (i = 0; hwcaps[i].matches; i++)
-		if (hwcaps[i].matches(&hwcaps[i]))
-			cap_set_elf_hwcap(&hwcaps[i]);
+	for (; hwcaps->matches; hwcaps++)
+		if (hwcaps->matches(hwcaps))
+			cap_set_elf_hwcap(hwcaps);
 }
 
 void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
 			    const char *info)
 {
-	int i;
-
-	for (i = 0; caps[i].matches; i++) {
-		if (!caps[i].matches(&caps[i]))
+	for (; caps->matches; caps++) {
+		if (!caps->matches(caps))
 			continue;
 
-		if (!cpus_have_cap(caps[i].capability) && caps[i].desc)
-			pr_info("%s %s\n", info, caps[i].desc);
-		cpus_set_cap(caps[i].capability);
+		if (!cpus_have_cap(caps->capability) && caps->desc)
+			pr_info("%s %s\n", info, caps->desc);
+		cpus_set_cap(caps->capability);
 	}
 }
 
@@ -838,11 +837,9 @@ void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
 static void __init
 enable_cpu_capabilities(const struct arm64_cpu_capabilities *caps)
 {
-	int i;
-
-	for (i = 0; caps[i].matches; i++)
-		if (caps[i].enable && cpus_have_cap(caps[i].capability))
-			on_each_cpu(caps[i].enable, NULL, true);
+	for (; caps->matches; caps++)
+		if (caps->enable && cpus_have_cap(caps->capability))
+			on_each_cpu(caps->enable, NULL, true);
 }
 
 /*
@@ -911,6 +908,41 @@ static void check_early_cpu_features(void)
 	verify_cpu_asid_bits();
 }
 
+static void
+verify_local_elf_hwcaps(const struct arm64_cpu_capabilities *caps)
+{
+
+	for (; caps->matches; caps++) {
+		if (!cpus_have_elf_hwcap(caps))
+			continue;
+		if (!feature_matches(__raw_read_system_reg(caps->sys_reg), caps)) {
+			pr_crit("CPU%d: missing HWCAP: %s\n",
+					smp_processor_id(), caps->desc);
+			cpu_die_early();
+		}
+	}
+}
+
+static void
+verify_local_cpu_features(const struct arm64_cpu_capabilities *caps)
+{
+	for (; caps->matches; caps++) {
+		if (!cpus_have_cap(caps->capability) || !caps->sys_reg)
+			continue;
+		/*
+		 * If the new CPU misses an advertised feature, we cannot proceed
+		 * further, park the cpu.
+		 */
+		if (!feature_matches(__raw_read_system_reg(caps->sys_reg), caps)) {
+			pr_crit("CPU%d: missing feature: %s\n",
+					smp_processor_id(), caps->desc);
+			cpu_die_early();
+		}
+		if (caps->enable)
+			caps->enable(NULL);
+	}
+}
+
 /*
  * Run through the enabled system capabilities and enable() it on this CPU.
  * The capabilities were decided based on the available CPUs at the boot time.
@@ -921,8 +953,6 @@ static void check_early_cpu_features(void)
  */
 void verify_local_cpu_capabilities(void)
 {
-	int i;
-	const struct arm64_cpu_capabilities *caps;
 
 	check_early_cpu_features();
 
@@ -933,32 +963,9 @@ void verify_local_cpu_capabilities(void)
 	if (!sys_caps_initialised)
 		return;
 
-	caps = arm64_features;
-	for (i = 0; caps[i].matches; i++) {
-		if (!cpus_have_cap(caps[i].capability) || !caps[i].sys_reg)
-			continue;
-		/*
-		 * If the new CPU misses an advertised feature, we cannot proceed
-		 * further, park the cpu.
-		 */
-		if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i])) {
-			pr_crit("CPU%d: missing feature: %s\n",
-					smp_processor_id(), caps[i].desc);
-			cpu_die_early();
-		}
-		if (caps[i].enable)
-			caps[i].enable(NULL);
-	}
-
-	for (i = 0, caps = arm64_elf_hwcaps; caps[i].matches; i++) {
-		if (!cpus_have_elf_hwcap(&caps[i]))
-			continue;
-		if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i])) {
-			pr_crit("CPU%d: missing HWCAP: %s\n",
-					smp_processor_id(), caps[i].desc);
-			cpu_die_early();
-		}
-	}
+	verify_local_cpu_features(arm64_features);
+	verify_local_elf_hwcaps(arm64_elf_hwcaps);
+	verify_local_elf_hwcaps(compat_elf_hwcaps);
 }
 
 static void __init setup_feature_capabilities(void)
@@ -974,7 +981,8 @@ void __init setup_cpu_features(void)
 
 	/* Set the CPU feature capabilies */
 	setup_feature_capabilities();
-	setup_elf_hwcaps();
+	setup_elf_hwcaps(arm64_elf_hwcaps);
+	setup_elf_hwcaps(compat_elf_hwcaps);
 
 	/* Advertise that we have computed the system capabilities */
 	set_sys_caps_initialised();
-- 
1.7.9.5

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#1381421 — [PATCH v4 1/6] arm64: hwcaps: Cleanup naming

We use hwcaps for referring to ELF hwcaps capability information.
However this can be confusing with 'cpu_hwcaps' which stands for the
CPU capability bit field. This patch cleans up the names to make it
a bit more readable.

Tested-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 arch/arm64/kernel/cpufeature.c |   18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 943f514..23b0f15 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -740,7 +740,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.hwcap = cap,					\
 	}
 
-static const struct arm64_cpu_capabilities arm64_hwcaps[] = {
+static const struct arm64_cpu_capabilities arm64_elf_hwcaps[] = {
 	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_AES_SHIFT, FTR_UNSIGNED, 2, CAP_HWCAP, HWCAP_PMULL),
 	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_AES_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_AES),
 	HWCAP_CAP(SYS_ID_AA64ISAR0_EL1, ID_AA64ISAR0_SHA1_SHIFT, FTR_UNSIGNED, 1, CAP_HWCAP, HWCAP_SHA1),
@@ -761,7 +761,7 @@ static const struct arm64_cpu_capabilities arm64_hwcaps[] = {
 	{},
 };
 
-static void __init cap_set_hwcap(const struct arm64_cpu_capabilities *cap)
+static void __init cap_set_elf_hwcap(const struct arm64_cpu_capabilities *cap)
 {
 	switch (cap->hwcap_type) {
 	case CAP_HWCAP:
@@ -782,7 +782,7 @@ static void __init cap_set_hwcap(const struct arm64_cpu_capabilities *cap)
 }
 
 /* Check if we have a particular HWCAP enabled */
-static bool __maybe_unused cpus_have_hwcap(const struct arm64_cpu_capabilities *cap)
+static bool cpus_have_elf_hwcap(const struct arm64_cpu_capabilities *cap)
 {
 	bool rc;
 
@@ -806,14 +806,14 @@ static bool __maybe_unused cpus_have_hwcap(const struct arm64_cpu_capabilities *
 	return rc;
 }
 
-static void __init setup_cpu_hwcaps(void)
+static void __init setup_elf_hwcaps(void)
 {
 	int i;
-	const struct arm64_cpu_capabilities *hwcaps = arm64_hwcaps;
+	const struct arm64_cpu_capabilities *hwcaps = arm64_elf_hwcaps;
 
 	for (i = 0; hwcaps[i].matches; i++)
 		if (hwcaps[i].matches(&hwcaps[i]))
-			cap_set_hwcap(&hwcaps[i]);
+			cap_set_elf_hwcap(&hwcaps[i]);
 }
 
 void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
@@ -950,8 +950,8 @@ void verify_local_cpu_capabilities(void)
 			caps[i].enable(NULL);
 	}
 
-	for (i = 0, caps = arm64_hwcaps; caps[i].matches; i++) {
-		if (!cpus_have_hwcap(&caps[i]))
+	for (i = 0, caps = arm64_elf_hwcaps; caps[i].matches; i++) {
+		if (!cpus_have_elf_hwcap(&caps[i]))
 			continue;
 		if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i])) {
 			pr_crit("CPU%d: missing HWCAP: %s\n",
@@ -974,7 +974,7 @@ void __init setup_cpu_features(void)
 
 	/* Set the CPU feature capabilies */
 	setup_feature_capabilities();
-	setup_cpu_hwcaps();
+	setup_elf_hwcaps();
 
 	/* Advertise that we have computed the system capabilities */
 	set_sys_caps_initialised();
-- 
1.7.9.5

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