Fix __ASSUME_RECVMMSG issues (bug 16610).

Similar to the issues for accept4, __ASSUME_RECVMMSG is also confused
about whether it relates to function availability or socketcall
operation availability; this is now bug 16610.

Nothing actually tests __ASSUME_RECVMMSG for function availability,
but implicit in the definition in kernel-features.h is the idea that
it makes sense when the syscall is available and socketcall is not
being used.  As with accept4, there are architectures where the
syscall was added later than the socketcall operation, meaning that
assuming glibc is built with recent enough kernel headers, it does not
attempt to use socketcall for these operations and __ASSUME_RECVMMSG
gets defined for kernels >= 2.6.33 even when the syscall was only
added later.

This patch splits the macro into separate macros like those used for
accept4; having similar macro structure in both cases (and for
sendmmsg once I've dealt with that) seems likely to be less confusing
than having a different structure on the basis of nothing actually
needing to assume the recvmmsg function works.  Appropriate
definitions are added for all architectures.

Architecture-specific note: Tile's kernel-features.h says "TILE glibc
support starts with 2.6.36", which is accurate in that 2.6.36 was the
first kernel version with Tile support, and on that basis I've made
that header define __ASSUME_RECVMMSG_SYSCALL unconditionally.
However, Tile's configure.ac has arch_minimum_kernel=2.6.32.  Since
arch_minimum_kernel is meant to reflect only kernel.org kernel
versions, I think that should change to 2.6.36.  (If using glibc with
kernel versions from before a port went in kernel.org, it's your
responsibility to change arch_minimum_kernel in a local patch, and at
the same time to adjust any __ASSUME_* definitions that may not be
correct for your older kernel; for developing the official glibc it
should only ever be necessary to consider what official kernel.org
releases support.)

Tested x86_64, including that disassembly of the installed shared
libraries is unchanged by this patch.

	[BZ #16610]
	* sysdeps/unix/sysv/linux/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020621 && __ASSUME_SOCKETCALL]
	(__ASSUME_RECVMMSG_SOCKETCALL): Define.
	[(__LINUX_KERNEL_VERSION >= 0x020621 && (__i386__ || __x86_64__ ||
	__sparc__)) || (__LINUX_KERNEL_VERSION >= 0x020625 && (__powerpc__
	|| __sh__))] (__ASSUME_RECVMMSG_SYSCALL): Likewise.
	[__i386__ || __sparc__]
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	[__ASSUME_RECVMMSG_SOCKETCALL || __ASSUME_RECVMMSG_SYSCALL]
	(__ASSUME_RECVMMSG): Define instead of using previous
	[__LINUX_KERNEL_VERSION >= 0x020621] condition.
	* sysdeps/unix/sysv/linux/aarch64/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL): Define.
	* sysdeps/unix/sysv/linux/alpha/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_RECVMMSG_SYSCALL):
	Likewise.
	* sysdeps/unix/sysv/linux/arm/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_RECVMMSG_SYSCALL):
	Likewise.
	* sysdeps/unix/sysv/linux/ia64/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_RECVMMSG_SYSCALL):
	Likewise.
	* sysdeps/unix/sysv/linux/internal_recvmmsg.S [__ASSUME_SOCKETCALL
	&& !__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL &&
	!__ASSUME_RECVMMSG_SYSCALL] (__NR_recvmmsg): Undefine.
	[__ASSUME_RECVMMSG]: Change condition to
	[__ASSUME_RECVMMSG_SOCKETCALL].
	* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_RECVMMSG_SYSCALL):
	Define.
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	* sysdeps/unix/sysv/linux/mips/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_RECVMMSG_SYSCALL):
	Likewise.
	* sysdeps/unix/sysv/linux/recvmmsg.c [__ASSUME_SOCKETCALL &&
	!__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL &&
	!__ASSUME_RECVMMSG_SYSCALL] (__NR_recvmmsg): Undefine.
	[!__ASSUME_RECVMMSG]: Change condition to
	[!__ASSUME_RECVMMSG_SOCKETCALL].
	* sysdeps/unix/sysv/linux/tile/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL): Define.

	* sysdeps/unix/sysv/linux/hppa/kernel-features.h
	[__LINUX_KERNEL_VERSION >= 0x020622] (__ASSUME_RECVMMSG_SYSCALL):
	Define.

1 files changed, 11 insertions, 2 deletions

diff --git a/sysdeps/unix/sysv/linux/recvmmsg.c b/sysdeps/unix/sysv/linux/recvmmsg.c
index 04ff42ee72..57ddf3152a 100644
--- a/sysdeps/unix/sysv/linux/recvmmsg.c
+++ b/sysdeps/unix/sysv/linux/recvmmsg.c
@@ -23,6 +23,14 @@
 #include <sys/syscall.h>
 #include <kernel-features.h>
 
+/* Do not use the recvmmsg syscall on socketcall architectures unless
+   it was added at the same time as the socketcall support or can be
+   assumed to be present.  */
+#if defined __ASSUME_SOCKETCALL \
+    && !defined __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL \
+    && !defined __ASSUME_RECVMMSG_SYSCALL
+# undef __NR_recvmmsg
+#endif
 
 #ifdef __NR_recvmmsg
 int
@@ -41,7 +49,7 @@ recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
   return result;
 }
 #elif defined __NR_socketcall
-# ifndef __ASSUME_RECVMMSG
+# ifndef __ASSUME_RECVMMSG_SOCKETCALL
 extern int __internal_recvmmsg (int fd, struct mmsghdr *vmessages,
 				unsigned int vlen, int flags,
 				const struct timespec *tmo)
@@ -85,7 +93,8 @@ recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
   return -1;
 }
 # else
-/* When __ASSUME_RECVMMSG recvmmsg is defined in internal_recvmmsg.S.  */
+/* When __ASSUME_RECVMMSG_SOCKETCALL recvmmsg is defined in
+   internal_recvmmsg.S.  */
 # endif
 #else
 # include <socket/recvmmsg.c>