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Fix __ASSUME_ACCEPT4 issues (bug 16609)
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Cc: Aurelien Jarno <aurelien at aurel32 dot net>, Richard Henderson <rth at redhat dot com>
- Date: Wed, 19 Feb 2014 22:08:10 +0000
- Subject: Fix __ASSUME_ACCEPT4 issues (bug 16609)
- Authentication-results: sourceware.org; auth=none
In <https://sourceware.org/ml/libc-alpha/2013-12/msg00008.html>,
Aurelien noted issues with the definition of __ASSUME_ACCEPT4, which I
discussed in more detail in
<https://sourceware.org/ml/libc-alpha/2013-12/msg00014.html>; these
are now bug 16609.
As previously noted, __ASSUME_ACCEPT4 is used in two ways:
* In OS-independent code, to mean "accept4 can be assumed to work
rather than fail with ENOSYS". It doesn't matter whether it's
implemented with socketcall or a separate syscall.
* In Linux-specific code, to mean "the socketcall multiplex syscall
can be assumed to handle the accept4 operation. When used in
Linux-specific code, it *never* refers to anything relating to the
accept4 syscall, only to the socketcall multiplexer.
This patch splits the macro into separate __ASSUME_ACCEPT4_SOCKETCALL,
__ASSUME_ACCEPT4_SYSCALL and __ASSUME_ACCEPT4 to clarify the different
cases involved. A macro __ASSUME_SOCKETCALL is added for convenience
in writing logic relating to all socketcall architectures. In
addition, to address the issue of architectures where socketcall
support for accept4 was added before a separate syscall was added (and
so the separate syscall should not be used unless known to be present
or fallback to socketcall is available), a fourth macro
__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL is added to indicate that the
syscall became available at the same time as socketcall support. This
is then used in the relevant places in a conditional determining
whether to undefine __NR_accept4 (the simple approach to avoiding the
syscall's presence causing problems; I didn't try to implement runtime
fallback from the syscall to socketcall).
Architecture-specific note: alpha defined __ASSUME_ACCEPT4 for 2.6.33
and later, but actually the syscall was added for alpha in 3.2, so
this patch uses the correct condition for __ASSUME_ACCEPT4_SYSCALL
there.
Tested x86_64, including that disassembly of the installed shared
libraries is unchanged by this patch.
2014-02-19 Joseph Myers <joseph@codesourcery.com>
[BZ #16609]
* sysdeps/unix/sysv/linux/kernel-features.h [__i386__ ||
__powerpc__ || __s390__ || __sh__ || __sparc__]
(__ASSUME_SOCKETCALL): Define.
[__LINUX_KERNEL_VERSION && __ASSUME_SOCKETCALL]
(__ASSUME_ACCEPT4_SOCKETCALL): Define.
[(__LINUX_KERNEL_VERSION >= 0x02061c && (__x86_64__ || __sparc__))
|| (__LINUX_KERNEL_VERSION >= 0x020625 && (__powerpc__ ||
__sh__))] (__ASSUME_ACCEPT4_SYSCALL): Define.
[__sparc__] (__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL): Define.
[__ASSUME_ACCEPT4_SOCKETCALL || __ASSUME_ACCEPT4_SYSCALL]
(__ASSUME_ACCEPT4): Define instead of using previous
[__LINUX_KERNEL_VERSION >= 0x02061c && (__i386__ || __x86_64__ ||
__powerpc__ || __sparc__ || __s390__)] condition.
* sysdeps/unix/sysv/linux/aarch64/kernel-features.h
(__ASSUME_ACCEPT4): Change to __ASSUME_ACCEPT4_SYSCALL.
* sysdeps/unix/sysv/linux/accept4.c [__ASSUME_SOCKETCALL &&
!__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL &&
!__ASSUME_ACCEPT4_SYSCALL] (__NR_accept4): Undefine.
[!__ASSUME_ACCEPT4]: Change condition to
[!__ASSUME_ACCEPT4_SOCKETCALL].
* sysdeps/unix/sysv/linux/alpha/kernel-features.h
(__ASSUME_ACCEPT4): Change to __ASSUME_ACCEPT4_SYSCALL. Correct
condition to [__LINUX_KERNEL_VERSION >= 0x030200].
* sysdeps/unix/sysv/linux/arm/kernel-features.h
[__LINUX_KERNEL_VERSION >= 0x020624] (__ASSUME_ACCEPT4): Change to
__ASSUME_ACCEPT4_SYSCALL.
* sysdeps/unix/sysv/linux/i386/accept4.S [__ASSUME_ACCEPT4]:
Change conditions to [__ASSUME_ACCEPT4_SOCKETCALL].
* sysdeps/unix/sysv/linux/ia64/kernel-features.h
[__LINUX_KERNEL_VERSION >= 0x030300] (__ASSUME_ACCEPT4): Change to
__ASSUME_ACCEPT4_SYSCALL.
* sysdeps/unix/sysv/linux/internal_accept4.S [__ASSUME_SOCKETCALL
&& !__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL &&
!__ASSUME_ACCEPT4_SYSCALL] (__NR_accept4): Undefine.
[__ASSUME_ACCEPT4]: Change condition to
[__ASSUME_ACCEPT4_SOCKETCALL].
* sysdeps/unix/sysv/linux/m68k/kernel-features.h
(__ASSUME_SOCKETCALL): Define.
[__LINUX_KERNEL_VERSION >= 0x02061c] (__ASSUME_ACCEPT4): Remove.
* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
(__ASSUME_SOCKETCALL): Define.
(__ASSUME_ACCEPT4): Remove.
[__LINUX_KERNEL_VERSION >= 0x020621] (__ASSUME_ACCEPT4_SYSCALL):
Define.
* sysdeps/unix/sysv/linux/mips/kernel-features.h
[__LINUX_KERNEL_VERSION >= 0x02061f] (__ASSUME_ACCEPT4_SYSCALL):
Define.
* sysdeps/unix/sysv/linux/tile/kernel-features.h
(__ASSUME_ACCEPT4): Change to __ASSUME_ACCEPT4_SYSCALL.
ports/ChangeLog.hppa:
2014-02-19 Joseph Myers <joseph@codesourcery.com>
[BZ #16609]
* sysdeps/unix/sysv/linux/hppa/kernel-features.h
[__LINUX_KERNEL_VERSION >= 0x020622] (__ASSUME_ACCEPT4_SYSCALL):
Define.
diff --git a/ports/sysdeps/unix/sysv/linux/hppa/kernel-features.h b/ports/sysdeps/unix/sysv/linux/hppa/kernel-features.h
index e050c27..b8abd08 100644
--- a/ports/sysdeps/unix/sysv/linux/hppa/kernel-features.h
+++ b/ports/sysdeps/unix/sysv/linux/hppa/kernel-features.h
@@ -30,4 +30,9 @@
/* PA-RISC 2.6.9 kernels had the first LWS CAS support */
#define __ASSUME_LWS_CAS 1
+/* Support for the accept4 syscall was added in 2.6.34. */
+#if __LINUX_KERNEL_VERSION >= 0x020622
+# define __ASSUME_ACCEPT4_SYSCALL 1
+#endif
+
#include_next <kernel-features.h>
diff --git a/sysdeps/unix/sysv/linux/aarch64/kernel-features.h b/sysdeps/unix/sysv/linux/aarch64/kernel-features.h
index c736eb9..222b61c 100644
--- a/sysdeps/unix/sysv/linux/aarch64/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/aarch64/kernel-features.h
@@ -24,7 +24,7 @@
/* AArch64 support starts with 3.7.0, guaranteeing many kernel
features. */
-#define __ASSUME_ACCEPT4 1
+#define __ASSUME_ACCEPT4_SYSCALL 1
#define __ASSUME_DUP3 1
#define __ASSUME_EVENTFD2 1
#define __ASSUME_IN_NONBLOCK 1
diff --git a/sysdeps/unix/sysv/linux/accept4.c b/sysdeps/unix/sysv/linux/accept4.c
index 019e96b..a017224 100644
--- a/sysdeps/unix/sysv/linux/accept4.c
+++ b/sysdeps/unix/sysv/linux/accept4.c
@@ -24,6 +24,14 @@
#include <sys/syscall.h>
#include <kernel-features.h>
+/* Do not use the accept4 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_ACCEPT4_SYSCALL_WITH_SOCKETCALL \
+ && !defined __ASSUME_ACCEPT4_SYSCALL
+# undef __NR_accept4
+#endif
#ifdef __NR_accept4
int
@@ -42,7 +50,7 @@ accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
return result;
}
#elif defined __NR_socketcall
-# ifndef __ASSUME_ACCEPT4
+# ifndef __ASSUME_ACCEPT4_SOCKETCALL
extern int __internal_accept4 (int fd, __SOCKADDR_ARG addr,
socklen_t *addr_len, int flags)
attribute_hidden;
@@ -83,7 +91,8 @@ accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
return -1;
}
# else
-/* When __ASSUME_ACCEPT4 accept4 is defined in internal_accept4.S. */
+/* When __ASSUME_ACCEPT4_SOCKETCALL accept4 is defined in
+ internal_accept4.S. */
# endif
#else
int
diff --git a/sysdeps/unix/sysv/linux/alpha/kernel-features.h b/sysdeps/unix/sysv/linux/alpha/kernel-features.h
index 7c38854..8cceb34 100644
--- a/sysdeps/unix/sysv/linux/alpha/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/alpha/kernel-features.h
@@ -42,9 +42,9 @@
# define __ASSUME_SIGNALFD4 1
#endif
-/* Support for accept4 was added for alpha after 2.6.33-rc1. */
-#if __LINUX_KERNEL_VERSION >= 0x020621
-# define __ASSUME_ACCEPT4 1
+/* Support for accept4 was added for alpha in 3.2. */
+#if __LINUX_KERNEL_VERSION >= 0x030200
+# define __ASSUME_ACCEPT4_SYSCALL 1
#endif
#include_next <kernel-features.h>
diff --git a/sysdeps/unix/sysv/linux/arm/kernel-features.h b/sysdeps/unix/sysv/linux/arm/kernel-features.h
index 9d7ef87..304f88d 100644
--- a/sysdeps/unix/sysv/linux/arm/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/arm/kernel-features.h
@@ -33,7 +33,7 @@
/* Support for the accept4 syscall was added in 2.6.36. */
#if __LINUX_KERNEL_VERSION >= 0x020624
-# define __ASSUME_ACCEPT4 1
+# define __ASSUME_ACCEPT4_SYSCALL 1
#endif
#include_next <kernel-features.h>
diff --git a/sysdeps/unix/sysv/linux/i386/accept4.S b/sysdeps/unix/sysv/linux/i386/accept4.S
index cdce27b..2021399 100644
--- a/sysdeps/unix/sysv/linux/i386/accept4.S
+++ b/sysdeps/unix/sysv/linux/i386/accept4.S
@@ -23,7 +23,7 @@
#define EINVAL 22
#define ENOSYS 38
-#ifdef __ASSUME_ACCEPT4
+#ifdef __ASSUME_ACCEPT4_SOCKETCALL
# define errlabel SYSCALL_ERROR_LABEL
#else
# define errlabel .Lerr
@@ -114,7 +114,7 @@ ENTRY (__libc_accept4)
ret
#endif
-#ifndef __ASSUME_ACCEPT4
+#ifndef __ASSUME_ACCEPT4_SOCKETCALL
/* The kernel returns -EINVAL for unknown socket operations.
We need to convert that error to an ENOSYS error. */
.Lerr: cmpl $-EINVAL, %eax
diff --git a/sysdeps/unix/sysv/linux/ia64/kernel-features.h b/sysdeps/unix/sysv/linux/ia64/kernel-features.h
index 340f679..5c7c4eb 100644
--- a/sysdeps/unix/sysv/linux/ia64/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/ia64/kernel-features.h
@@ -49,7 +49,7 @@
/* Support for the accept4 syscall was added in 3.3. */
#if __LINUX_KERNEL_VERSION >= 0x030300
-# define __ASSUME_ACCEPT4 1
+# define __ASSUME_ACCEPT4_SYSCALL 1
#endif
#include_next <kernel-features.h>
diff --git a/sysdeps/unix/sysv/linux/internal_accept4.S b/sysdeps/unix/sysv/linux/internal_accept4.S
index ffc5536..f0c61b5 100644
--- a/sysdeps/unix/sysv/linux/internal_accept4.S
+++ b/sysdeps/unix/sysv/linux/internal_accept4.S
@@ -1,8 +1,18 @@
#include <kernel-features.h>
#include <sys/syscall.h>
+
+/* Do not use the accept4 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_ACCEPT4_SYSCALL_WITH_SOCKETCALL \
+ && !defined __ASSUME_ACCEPT4_SYSCALL
+# undef __NR_accept4
+#endif
+
#if !defined __NR_accept4 && defined __NR_socketcall
# define socket accept4
-# ifdef __ASSUME_ACCEPT4
+# ifdef __ASSUME_ACCEPT4_SOCKETCALL
# define __socket accept4
# else
# define __socket __internal_accept4
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index 784f4dd..b6d7714 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -40,6 +40,18 @@
/* The sendfile syscall was introduced in 2.2.0. */
#define __ASSUME_SENDFILE 1
+/* Some architectures use the socketcall multiplexer for some or all
+ socket-related operations, via a socket.S file in glibc, instead of
+ separate syscalls. __ASSUME_SOCKETCALL is defined for such
+ architectures. */
+#if defined __i386__ \
+ || defined __powerpc__ \
+ || defined __s390__ \
+ || defined __sh__ \
+ || defined __sparc__
+# define __ASSUME_SOCKETCALL 1
+#endif
+
/* Linux 2.3.39 introduced IPC64. Except for powerpc. Linux 2.4.0 on
PPC introduced a correct IPC64. But PowerPC64 does not support a
separate 64-bit syscall, already 64-bit. */
@@ -164,10 +176,34 @@
# define __ASSUME_DUP3 1
#endif
-/* Support for the accept4 syscall was added in 2.6.28. */
-#if __LINUX_KERNEL_VERSION >= 0x02061c \
- && (defined __i386__ || defined __x86_64__ || defined __powerpc__ \
- || defined __sparc__ || defined __s390__)
+/* Support for accept4 functionality was added in 2.6.28, but for some
+ architectures using a separate syscall rather than socketcall that
+ syscall was only added later, and some architectures first had
+ socketcall support then a separate syscall. Define
+ __ASSUME_ACCEPT4_SOCKETCALL if glibc uses socketcall on this
+ architecture and accept4 is available through socketcall,
+ __ASSUME_ACCEPT4_SYSCALL if it is available through a separate
+ syscall, __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL if it became
+ available through a separate syscall at the same time as through
+ socketcall, and __ASSUME_ACCEPT4 if the accept4 function is known
+ to work. */
+#if __LINUX_KERNEL_VERSION >= 0x02061c && defined __ASSUME_SOCKETCALL
+# define __ASSUME_ACCEPT4_SOCKETCALL 1
+#endif
+
+/* The accept4 syscall was added for x86_64 and SPARC in 2.6.28, and
+ for PowerPC and SH in 2.6.37. */
+#if (__LINUX_KERNEL_VERSION >= 0x02061c \
+ && (defined __x86_64__ || defined __sparc__)) \
+ || (__LINUX_KERNEL_VERSION >= 0x020625 \
+ && (defined __powerpc__ || defined __sh__))
+# define __ASSUME_ACCEPT4_SYSCALL 1
+#endif
+#ifdef __sparc__
+# define __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL 1
+#endif
+
+#if defined __ASSUME_ACCEPT4_SOCKETCALL || defined __ASSUME_ACCEPT4_SYSCALL
# define __ASSUME_ACCEPT4 1
#endif
diff --git a/sysdeps/unix/sysv/linux/m68k/kernel-features.h b/sysdeps/unix/sysv/linux/m68k/kernel-features.h
index 3b05e96..cb8915f 100644
--- a/sysdeps/unix/sysv/linux/m68k/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/m68k/kernel-features.h
@@ -17,6 +17,9 @@
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
+/* m68k uses socketcall. */
+#define __ASSUME_SOCKETCALL 1
+
/* Many syscalls were added in 2.6.10 for m68k. */
#define __ASSUME_UTIMES 1
@@ -35,11 +38,6 @@
# define __ASSUME_DUP3 1
#endif
-/* Support for the accept4 syscall was added in 2.6.28. */
-#if __LINUX_KERNEL_VERSION >= 0x02061c
-# define __ASSUME_ACCEPT4 1
-#endif
-
#include_next <kernel-features.h>
/* These syscalls were added only in 3.0 for m68k. */
diff --git a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
index dcc0ac9..413b4a0 100644
--- a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
@@ -16,6 +16,9 @@
<http://www.gnu.org/licenses/>. */
+/* MicroBlaze uses socketcall. */
+#define __ASSUME_SOCKETCALL 1
+
/* MicroBlaze glibc support starts with 2.6.30, guaranteeing many kernel features. */
#define __ASSUME_UTIMES 1
#define __ASSUME_O_CLOEXEC 1
@@ -24,7 +27,11 @@
#define __ASSUME_PIPE2 1
#define __ASSUME_EVENTFD2 1
#define __ASSUME_SIGNALFD4 1
-#define __ASSUME_ACCEPT4 1
#define __ASSUME_DUP3 1
+/* Support for the accept4 syscall was added in 2.6.33. */
+#if __LINUX_KERNEL_VERSION >= 0x020621
+# define __ASSUME_ACCEPT4_SYSCALL 1
+#endif
+
#include_next <kernel-features.h>
diff --git a/sysdeps/unix/sysv/linux/mips/kernel-features.h b/sysdeps/unix/sysv/linux/mips/kernel-features.h
index 1c83ee5..94deaf9 100644
--- a/sysdeps/unix/sysv/linux/mips/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/mips/kernel-features.h
@@ -31,6 +31,11 @@
# define __ASSUME_SIGNALFD4 1
#endif
+/* Support for the accept4 syscall was added in 2.6.31. */
+#if __LINUX_KERNEL_VERSION >= 0x02061f
+# define __ASSUME_ACCEPT4_SYSCALL 1
+#endif
+
#include_next <kernel-features.h>
/* The n32 syscall ABI did not have a getdents64 syscall until
diff --git a/sysdeps/unix/sysv/linux/tile/kernel-features.h b/sysdeps/unix/sysv/linux/tile/kernel-features.h
index 5b81128..e339e7a 100644
--- a/sysdeps/unix/sysv/linux/tile/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/tile/kernel-features.h
@@ -25,7 +25,7 @@
#define __ASSUME_PIPE2 1
#define __ASSUME_EVENTFD2 1
#define __ASSUME_SIGNALFD4 1
-#define __ASSUME_ACCEPT4 1
+#define __ASSUME_ACCEPT4_SYSCALL 1
#define __ASSUME_DUP3 1
#include_next <kernel-features.h>
--
Joseph S. Myers
joseph@codesourcery.com