[PATCH v2 resend 0/5] arm64: advertise availability of CRC and crypto instructions

This series is a followup to the patch that was recently merged by Catalin that
allocates hwcaps bits for CRC and Crypto Extensions instructions so userland can
discover whether the current CPU has any of those capabilities.

Patch #1 enables ARM support for the ELF_HWCAP2/AT_HWCAP2 ELF auxv entry that
was recently added to the kernel and glibc (2.18). It extends the feature bit
space to 64 bits (on 32-bit architectures)

Patch #2 adds generic support for ELF_HWCAP2/AT_HWCAP2 to the 32-bit ELF compat
mode for 64-bit architectures.

Patch #3 adds support for ELF_HWCAP2/AT_HWCAP2 to arm64's 32-bit ELF compat mode

Patch #4 allocates the HWCAP2 bits in the arch/arm tree. This is necessary
because 32-bit ARM binaries can execute both under ARM and under arm64 kernels,
so there should be agreement about the meaning of feature bits, even if the ARM
kernel has no support yet for ARMv8 32-bit only hardware (such as ARMv8-R)

Patch #5 advertises the CRC and Crypto Extensions to 32-bit ELF binaries running
under an arm64 kernel.

v2 changes:
- omitted 2 arm64 specific patches that have already been merged by Catalin
- move ARM feature bits to HWCAP2

Ard Biesheuvel (5):
  ARM: add support for AT_HWCAP2 ELF auxv entry
  binfmt_elf: add ELF_HWCAP2 to compat auxv entries
  arm64: add AT_HWCAP2 support for 32-bit compat
  ARM: introduce HWCAP2 feature bits for ARMv8 Crypto Extensions
  arm64: advertise ARMv8 extensions to 32-bit compat ELF binaries

 arch/arm/include/asm/hwcap.h      |  3 ++-
 arch/arm/include/uapi/asm/hwcap.h |  9 +++++++++
 arch/arm/kernel/setup.c           | 16 ++++++++++++++++
 arch/arm64/include/asm/hwcap.h    |  9 ++++++++-
 arch/arm64/kernel/setup.c         | 33 +++++++++++++++++++++++++++++++++
 fs/compat_binfmt_elf.c            |  5 +++++
 6 files changed, 73 insertions(+), 2 deletions(-)

-- 
1.8.3.2

Add ELF_HWCAP2 to the set of auxv entries that is passed to
a 32-bit ELF program running in 32-bit compat mode under a
64-bit kernel.

Signed-off-by: Ard Biesheuvel <redacted>
---
 fs/compat_binfmt_elf.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c
index a81147e2e4ef..4d24d17bcfc1 100644
--- a/fs/compat_binfmt_elf.c
+++ b/fs/compat_binfmt_elf.c

@@ -88,6 +88,11 @@ static void cputime_to_compat_timeval(const cputime_t cputime,
 #define	ELF_HWCAP		COMPAT_ELF_HWCAP
 #endif
 
+#ifdef	COMPAT_ELF_HWCAP2
+#undef	ELF_HWCAP2
+#define	ELF_HWCAP2		COMPAT_ELF_HWCAP2
+#endif
+
 #ifdef	COMPAT_ARCH_DLINFO
 #undef	ARCH_DLINFO
 #define	ARCH_DLINFO		COMPAT_ARCH_DLINFO

-- 
1.8.3.2

This enables AT_HWCAP2 for ARM. The generic support for this
new ELF auxv entry was added in commit 2171364d1a9 (powerpc:
Add HWCAP2 aux entry)

Signed-off-by: Ard Biesheuvel <redacted>
---
 arch/arm/include/asm/hwcap.h      |  3 ++-
 arch/arm/include/uapi/asm/hwcap.h |  4 ++++
 arch/arm/kernel/setup.c           | 11 +++++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/hwcap.h b/arch/arm/include/asm/hwcap.h
index 6ff56eca3f1f..6e183fd269fb 100644
--- a/arch/arm/include/asm/hwcap.h
+++ b/arch/arm/include/asm/hwcap.h

@@ -9,6 +9,7 @@
  * instruction set this cpu supports.
  */
 #define ELF_HWCAP	(elf_hwcap)
-extern unsigned int elf_hwcap;
+#define ELF_HWCAP2	(elf_hwcap2)
+extern unsigned int elf_hwcap, elf_hwcap2;
 #endif
 #endif

diff --git a/arch/arm/include/uapi/asm/hwcap.h b/arch/arm/include/uapi/asm/hwcap.h
index 7dcc10d67253..87768b5cffd1 100644
--- a/arch/arm/include/uapi/asm/hwcap.h
+++ b/arch/arm/include/uapi/asm/hwcap.h

@@ -28,4 +28,8 @@
 #define HWCAP_LPAE	(1 << 20)
 #define HWCAP_EVTSTRM	(1 << 21)
 
+/*
+ * HWCAP2 flags - for elf_hwcap2 (in kernel) and AT_HWCAP2
+ */
+
 #endif /* _UAPI__ASMARM_HWCAP_H */

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 987a7f5bce5f..ce3049c89c18 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c

@@ -100,6 +100,9 @@ EXPORT_SYMBOL(system_serial_high);
 unsigned int elf_hwcap __read_mostly;
 EXPORT_SYMBOL(elf_hwcap);
 
+unsigned int elf_hwcap2 __read_mostly;
+EXPORT_SYMBOL(elf_hwcap2);
+
 
 #ifdef MULTI_CPU
 struct processor processor __read_mostly;

@@ -992,6 +995,10 @@ static const char *hwcap_str[] = {
 	NULL
 };
 
+static const char *hwcap2_str[] = {
+	NULL
+};
+
 static int c_show(struct seq_file *m, void *v)
 {
 	int i, j;

@@ -1015,6 +1022,10 @@ static int c_show(struct seq_file *m, void *v)
 			if (elf_hwcap & (1 << j))
 				seq_printf(m, "%s ", hwcap_str[j]);
 
+		for (j = 0; hwcap2_str[j]; j++)
+			if (elf_hwcap2 & (1 << j))
+				seq_printf(m, "%s ", hwcap2_str[j]);
+
 		seq_printf(m, "\nCPU implementer\t: 0x%02x\n", cpuid >> 24);
 		seq_printf(m, "CPU architecture: %s\n",
 			   proc_arch[cpu_architecture()]);

-- 
1.8.3.2

Add support for the ELF auxv entry AT_HWCAP2 when running 32-bit
ELF binaries in compat mode.

Signed-off-by: Ard Biesheuvel <redacted>
---
 arch/arm64/include/asm/hwcap.h | 3 ++-
 arch/arm64/kernel/setup.c      | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 6cddbb0c9f54..9a4cbd60c88e 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h

@@ -41,7 +41,8 @@
 
 #ifdef CONFIG_COMPAT
 #define COMPAT_ELF_HWCAP	(compat_elf_hwcap)
-extern unsigned int compat_elf_hwcap;
+#define COMPAT_ELF_HWCAP2	(compat_elf_hwcap2)
+extern unsigned int compat_elf_hwcap, compat_elf_hwcap2;
 #endif
 
 extern unsigned long elf_hwcap;

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index bb33fff09ba2..15f3bd207981 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c

@@ -69,6 +69,7 @@ EXPORT_SYMBOL_GPL(elf_hwcap);
 				 COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\
 				 COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV)
 unsigned int compat_elf_hwcap __read_mostly = COMPAT_ELF_HWCAP_DEFAULT;
+unsigned int compat_elf_hwcap2 __read_mostly;
 #endif
 
 static const char *cpu_name;

-- 
1.8.3.2

This adds support for advertising the presence of ARMv8 Crypto
Extensions in the Aarch32 execution state to 32-bit ELF binaries
running in 32-bit compat mode under the arm64 kernel.

Signed-off-by: Ard Biesheuvel <redacted>
---
 arch/arm64/include/asm/hwcap.h |  6 ++++++
 arch/arm64/kernel/setup.c      | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 9a4cbd60c88e..024c46183c3c 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h

@@ -32,6 +32,12 @@
 #define COMPAT_HWCAP_IDIV	(COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT)
 #define COMPAT_HWCAP_EVTSTRM	(1 << 21)
 
+#define COMPAT_HWCAP2_AES	(1 << 0)
+#define COMPAT_HWCAP2_PMULL	(1 << 1)
+#define COMPAT_HWCAP2_SHA1	(1 << 2)
+#define COMPAT_HWCAP2_SHA2	(1 << 3)
+#define COMPAT_HWCAP2_CRC32	(1 << 4)
+
 #ifndef __ASSEMBLY__
 /*
  * This yields a mask that user programs can use to figure out what

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 15f3bd207981..c36cab831932 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c

@@ -174,6 +174,38 @@ static void __init setup_processor(void)
 	block = (features >> 16) & 0xf;
 	if (block && !(block & 0x8))
 		elf_hwcap |= HWCAP_CRC32;
+
+#ifdef CONFIG_COMPAT
+	/*
+	 * ID_ISAR5_EL1 carries similar information as above, but pertaining to
+	 * the Aarch32 32-bit execution state.
+	 */
+	features = read_cpuid(ID_ISAR5_EL1);
+	block = (features >> 4) & 0xf;
+	if (!(block & 0x8)) {
+		switch (block) {
+		default:
+		case 2:
+			compat_elf_hwcap2 |= COMPAT_HWCAP2_PMULL;
+		case 1:
+			compat_elf_hwcap2 |= COMPAT_HWCAP2_AES;
+		case 0:
+			break;
+		}
+	}
+
+	block = (features >> 8) & 0xf;
+	if (block && !(block & 0x8))
+		compat_elf_hwcap2 |= COMPAT_HWCAP2_SHA1;
+
+	block = (features >> 12) & 0xf;
+	if (block && !(block & 0x8))
+		compat_elf_hwcap2 |= COMPAT_HWCAP2_SHA2;
+
+	block = (features >> 16) & 0xf;
+	if (block && !(block & 0x8))
+		compat_elf_hwcap2 |= COMPAT_HWCAP2_CRC32;
+#endif
 }
 
 static void __init setup_machine_fdt(phys_addr_t dt_phys)

-- 
1.8.3.2

This allocates feature bits 0-4 in HWCAP2 for the crypto and CRC
extensions introduced in ARMv8.

Signed-off-by: Ard Biesheuvel <redacted>
---
 arch/arm/include/uapi/asm/hwcap.h | 5 +++++
 arch/arm/kernel/setup.c           | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/arch/arm/include/uapi/asm/hwcap.h b/arch/arm/include/uapi/asm/hwcap.h
index 87768b5cffd1..20d12f230a2f 100644
--- a/arch/arm/include/uapi/asm/hwcap.h
+++ b/arch/arm/include/uapi/asm/hwcap.h

@@ -31,5 +31,10 @@
 /*
  * HWCAP2 flags - for elf_hwcap2 (in kernel) and AT_HWCAP2
  */
+#define HWCAP2_AES	(1 << 0)
+#define HWCAP2_PMULL	(1 << 1)
+#define HWCAP2_SHA1	(1 << 2)
+#define HWCAP2_SHA2	(1 << 3)
+#define HWCAP2_CRC32	(1 << 4)
 
 #endif /* _UAPI__ASMARM_HWCAP_H */

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index ce3049c89c18..ac3a7f218b7f 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c

@@ -996,6 +996,11 @@ static const char *hwcap_str[] = {
 };
 
 static const char *hwcap2_str[] = {
+	"aes",
+	"pmull",
+	"sha1",
+	"sha2",
+	"crc32",
 	NULL
 };
 

-- 
1.8.3.2

Hi Ard,

On Fri, Jan 17, 2014 at 09:23:07AM +0000, Ard Biesheuvel wrote:

This enables AT_HWCAP2 for ARM. The generic support for this
new ELF auxv entry was added in commit 2171364d1a9 (powerpc:
Add HWCAP2 aux entry)

Does this require a corresponding change in libc so that the entry is
actually used by the dynamic linker?

Will

On 17 January 2014 16:07, Will Deacon [off-list ref] wrote:

Hi Ard,

On Fri, Jan 17, 2014 at 09:23:07AM +0000, Ard Biesheuvel wrote:

quoted

This enables AT_HWCAP2 for ARM. The generic support for this
new ELF auxv entry was added in commit 2171364d1a9 (powerpc:
Add HWCAP2 aux entry)

Does this require a corresponding change in libc so that the entry is
actually used by the dynamic linker?

The auxv entry itself is already wired up [this includes getauxval()]

https://sourceware.org/git/?p=glibc.git;a=commit;h=1ae8bfe07c1a

The only thing that is lacking is a way to hook up ifunc relocation,
as the current prototype passes a single 32-bit quantity.
So either we change the prototype to (hwcap, hwcap2) or we need to
rely on getauxval() in ifunc selectors if they need to inspect hwcap2

-- 
Ard.

On Fri, Jan 17, 2014 at 09:23:06AM +0000, Ard Biesheuvel wrote:

Ard Biesheuvel (5):
  ARM: add support for AT_HWCAP2 ELF auxv entry
  binfmt_elf: add ELF_HWCAP2 to compat auxv entries
  arm64: add AT_HWCAP2 support for 32-bit compat
  ARM: introduce HWCAP2 feature bits for ARMv8 Crypto Extensions
  arm64: advertise ARMv8 extensions to 32-bit compat ELF binaries

I think I acked this series but probably after you posted the resend.
Just in case I haven't:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

On Thu, Jan 23, 2014 at 03:01:23PM +0000, Catalin Marinas wrote:

On Fri, Jan 17, 2014 at 09:23:06AM +0000, Ard Biesheuvel wrote:

quoted

Ard Biesheuvel (5):
  ARM: add support for AT_HWCAP2 ELF auxv entry
  binfmt_elf: add ELF_HWCAP2 to compat auxv entries
  arm64: add AT_HWCAP2 support for 32-bit compat
  ARM: introduce HWCAP2 feature bits for ARMv8 Crypto Extensions
  arm64: advertise ARMv8 extensions to 32-bit compat ELF binaries

I think I acked this series but probably after you posted the resend.
Just in case I haven't:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Just to get things moving on this, I suggest you get an ack on the
binfmt_elf patch from Al Viro and linux-fsdevel or get them to merge
this patch. Afterwards, if there are no further comments from Russell,
you should send the arm patches to the patch system. Only after that
I'll update the compat arm64 support. Feel free to add my ack on the
whole series.

Thanks.

-- 
Catalin

On 5 February 2014 14:37, Catalin Marinas [off-list ref] wrote:

On Thu, Jan 23, 2014 at 03:01:23PM +0000, Catalin Marinas wrote:

quoted

On Fri, Jan 17, 2014 at 09:23:06AM +0000, Ard Biesheuvel wrote:

quoted

Ard Biesheuvel (5):
  ARM: add support for AT_HWCAP2 ELF auxv entry
  binfmt_elf: add ELF_HWCAP2 to compat auxv entries
  arm64: add AT_HWCAP2 support for 32-bit compat
  ARM: introduce HWCAP2 feature bits for ARMv8 Crypto Extensions
  arm64: advertise ARMv8 extensions to 32-bit compat ELF binaries

I think I acked this series but probably after you posted the resend.
Just in case I haven't:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Just to get things moving on this, I suggest you get an ack on the
binfmt_elf patch from Al Viro and linux-fsdevel or get them to merge
this patch. Afterwards, if there are no further comments from Russell,
you should send the arm patches to the patch system. Only after that
I'll update the compat arm64 support. Feel free to add my ack on the
whole series.

ARM patches submitted to the patch system as 7981/1 and 7982/1

Regards,
Ard.