[PATCH 0/5] Define AT_VECTOR_SIZE_ARCH correctly

[PATCH 0/5] Define AT_VECTOR_SIZE_ARCH correctly

[James Hogan]

Several architectures define ARCH_DLINFO to [sometimes] contain
NEW_AUX_ENT entries, but don't define AT_VECTOR_SIZE_ARCH with the
corresponding maximum number of NEW_AUX_ENT entries.

In practice this doesn't cause any problems as AT_VECTOR_SIZE_BASE
includes space for AT_BASE_PLATFORM which none of these arches use, but
nevertheless lets define it now and add the comment above ARCH_DLINFO as
found in several other architectures to remind future modifiers of
ARCH_DLINFO to keep AT_VECTOR_SIZE_ARCH up to date.

Arch maintainers, please take via your own trees if you're happy to do
so.

- I haven't included an update for x86/um as it doesn't follow the same
  pattern as other architectures so it is unclear to me whether it has
  the same issue.

- Build tested on MIPS, ARM & tile.

- Tested on MIPS.

James Hogan (5):
  MIPS: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO
  ARM: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO
  arm64: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO
  s390: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO
  tile: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO

 arch/arm/include/asm/elf.h           | 1 +
 arch/arm/include/uapi/asm/auxvec.h   | 2 ++
 arch/arm64/include/asm/elf.h         | 1 +
 arch/arm64/include/uapi/asm/auxvec.h | 2 ++
 arch/mips/include/asm/elf.h          | 1 +
 arch/mips/include/uapi/asm/auxvec.h  | 2 ++
 arch/s390/include/asm/elf.h          | 1 +
 arch/s390/include/uapi/asm/auxvec.h  | 2 ++
 arch/tile/include/asm/elf.h          | 1 +
 arch/tile/include/uapi/asm/auxvec.h  | 2 ++
 10 files changed, 15 insertions(+)

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Nathan Lynch <nathan_lynch@mentor.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: linux-mips@linux-mips.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: user-mode-linux-devel@lists.sourceforge.net
-- 
2.4.10

[PATCH 4/5] s390: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO

[James Hogan]

AT_VECTOR_SIZE_ARCH should be defined with the maximum number of
NEW_AUX_ENT entries that ARCH_DLINFO can contain, but it wasn't defined
for s390 at all even though ARCH_DLINFO can contain one NEW_AUX_ENT when
VDSO is enabled.

This shouldn't be a problem as AT_VECTOR_SIZE_BASE includes space for
AT_BASE_PLATFORM which s390 doesn't use, but lets define it now and add
the comment above ARCH_DLINFO as found in several other architectures to
remind future modifiers of ARCH_DLINFO to keep AT_VECTOR_SIZE_ARCH up to
date.

Fixes: b020632e40c3 ("[S390] introduce vdso on s390")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
---
 arch/s390/include/asm/elf.h         | 1 +
 arch/s390/include/uapi/asm/auxvec.h | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h
index 563ab9f44874..1736c7d3c94c 100644
--- a/arch/s390/include/asm/elf.h
+++ b/arch/s390/include/asm/elf.h
@@ -225,6 +225,7 @@ do {								\
 #define MMAP_ALIGN_MASK	(is_compat_task() ? 0 : 0x7fUL)
 #define STACK_RND_MASK	MMAP_RND_MASK
 
+/* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
 #define ARCH_DLINFO							    \
 do {									    \
 	if (vdso_enabled)						    \
diff --git a/arch/s390/include/uapi/asm/auxvec.h b/arch/s390/include/uapi/asm/auxvec.h
index a1f153e89133..c53e08442255 100644
--- a/arch/s390/include/uapi/asm/auxvec.h
+++ b/arch/s390/include/uapi/asm/auxvec.h
@@ -3,4 +3,6 @@
 
 #define AT_SYSINFO_EHDR		33
 
+#define AT_VECTOR_SIZE_ARCH 1 /* entries in ARCH_DLINFO */
+
 #endif
-- 
2.4.10

Re: [PATCH 4/5] s390: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO

[Martin Schwidefsky]

On Mon, 25 Jul 2016 16:59:53 +0100
James Hogan <james.hogan@imgtec.com> wrote:

> AT_VECTOR_SIZE_ARCH should be defined with the maximum number of
> NEW_AUX_ENT entries that ARCH_DLINFO can contain, but it wasn't defined
> for s390 at all even though ARCH_DLINFO can contain one NEW_AUX_ENT when
> VDSO is enabled.
> 
> This shouldn't be a problem as AT_VECTOR_SIZE_BASE includes space for
> AT_BASE_PLATFORM which s390 doesn't use, but lets define it now and add
> the comment above ARCH_DLINFO as found in several other architectures to
> remind future modifiers of ARCH_DLINFO to keep AT_VECTOR_SIZE_ARCH up to
> date.
> 
> Fixes: b020632e40c3 ("[S390] introduce vdso on s390")
> Signed-off-by: James Hogan <james.hogan@imgtec.com>
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: linux-s390@vger.kernel.org

The patch makes sense. I not quite sure about the checkpoint-restore code
that clears the last two entries of the user_auxv[] without knowing how
many aux entries there really are. That seems kind of strange.

I will the patch to our repositories and we'll give it a spin. If there
is no fallout I queue it to linux-s390.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.