Older ARC700 cores (ARC750 specifically) lack instructions to implement
atomic r-w-w. This is problematic for userspace libraries such as NPTL
which need atomic primitives. So enable them by providing kernel assist.
This is costly but really the only sane soluton (othern than tight
spinning using the otherwise availiable atomic exchange EX instruciton).
Good thing is there are only a few of these cores running Linux out in
the wild.
This only works on UP systems.
Reviewed-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Commit 97bc386fc1 "ARC: Add guard macro to uapi/asm/unistd.h"
inhibited multiple inclusion of ARCH unistd.h. This however hosed the system
since Generic syscall table generator relies on it being included twice,
and in lack-of an empty table was emitted by C preprocessor.
Fix that by allowing one exception to rule for the special case (just
like Xtensa)
Suggested-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Chen originally proposed this as "right thing to do" however I
actually ran into this when building perf tools. Some of the utils
include unistd.h as well as linux/unistd.h. Since -I includes kernel
headers too, we end up including the ARC unistd.h twice, leading to
redefinition nwarnings.
------------------>8-------------------
CC bench/sched-pipe.o
In file included from ~/kernel/arch/arc/include/uapi/asm/unistd.h:21:0,
from ~/kernel/include/uapi/linux/unistd.h:7,
from bench/sched-pipe.c:24:
~/kernel/include/uapi/asm-generic/unistd.h:889:0: error: "__NR_fcntl64"
redefined [-Werror]
#define __NR_fcntl64 __NR3264_fcntl
^
In file included from
~/gnu/arc-linux-uclibc/sys-include/sys/syscall.h:24:0,
from bench/../perf.h:112,
from bench/sched-pipe.c:13:
~/gnu/arc-linux-uclibc/include/bits/sysnum.h:761:0: note: this is the
location of the previous definition
------------------>8-------------------
Verified that make headers_install works fine with this.
Suggested-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: David Howells <dhowells@redhat.com>
1. ./genfilelist.pl arch/arc/include/asm/
2. Create arch/arc/include/uapi/asm/Kbuild as follows
+# UAPI Header export list
+include include/uapi/asm-generic/Kbuild.asm
3. ./disintegrate-one.pl arch/arc/include/{,uapi/}asm/<above-list>
4. Edit arch/arc/include/asm/Kbuild to remove ref to
asm-generic/Kbuild.asm
- To work around empty uapi/asm/setup.h added a placholder comment.
- Also a manual #ifdef __ASSEMBLY__ for a late ptrace change
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: David Howells <dhowells@redhat.com>
