Commit a074335a ("x86, um: Mark system call tables readonly") was
supposed to mark the sys_call_table in UML as RO by adding the const,
but it doesn't have the desired effect as it's nevertheless being placed
into the data section since __cacheline_aligned enforces sys_call_table
being placed into .data..cacheline_aligned instead. We need to use
the ____cacheline_aligned version instead to fix this issue.

Before:

$ nm -v arch/x86/um/sys_call_table_64.o | grep -1 "sys_call_table"
                 U sys_writev
0000000000000000 D sys_call_table
0000000000000000 D syscall_table_size

After:

$ nm -v arch/x86/um/sys_call_table_64.o | grep -1 "sys_call_table"
                 U sys_writev
0000000000000000 R sys_call_table
0000000000000000 D syscall_table_size

Fixes: a074335a ("x86, um: Mark system call tables readonly")
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NRichard Weinberger <richard@nod.at>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Conditional on CONFIG_GENERIC_SIGALTSTACK; architectures that do not
select it are completely unaffected
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

32bit wrapper is lost on that; 64bit one is *not*, since
we need to arrange for full pt_regs on stack when we call
sys_execve() and we need to load callee-saved ones from
there afterwards.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

we only use that to tell copy_thread() done by syscall from that
done by kernel_thread().  However, it's easier to do simply by
checking PF_KTHREAD in thread flags.

Merge sys_clone() guts for 32bit and 64bit, while we are at it...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

we only use that to tell copy_thread() done by syscall from that
done by kernel_thread().  However, it's easier to do simply by
checking PF_KTHREAD in thread flags.

Merge sys_clone() guts for 32bit and 64bit, while we are at it...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The latest GCC 4.8 does some more checking on type attributes that
break the build for ARCH=um -> fill them in.  Specifically, the
"asmlinkage" attributes is now tested for consistency.
Signed-off-by: NMartin Pelikan <pelikan@storkhole.cz>
Link: http://lkml.kernel.org/r/1339269731-10772-1-git-send-email-pelikan@storkhole.czAcked-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

We override sys_iopl(), not stub_iopl(); the latter is a 64-bitism
that doesn't apply to i386 in the first place.
Reported-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Mark the system call tables readonly, as they already are on native,
and the 32-bit UM version was in the previous assembly version.  The
32-bit version lost it due to copy and paste from the 64-bit version,
which was missing the const.

Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Link: http://lkml.kernel.org/r/tip-45db1c6176c8171d9ae6fa6d82e07d115a5950ca@git.kernel.orgSigned-off-by: NH. Peter Anvin <hpa@zytor.com>

Now when the native kernel uses a single style of generated system
call table, follow suite for UML and implement the same style, all in
C.  This requires __NR_syscall_max and NR_syscalls to be generated; on
native this is done in asm-headers.h but that file is common to all
UML architectures; therefore put it in user-headers.h instead which
already have accommodations for architecture-specific values.
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>