ARC port to uClibc

For this port, I would like to give due credit to:

- Folks from Codito technologies (Sameer, Amit, Kanika, Ramana,...)
   who did the very first port

- ARC UK from 2007-2009 (Joern, Irfan, Khurram, Phil...

- Late Brendan Kehoe (may he RIP)

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

1 files changed, 192 insertions, 0 deletions

diff --git a/libc/sysdeps/linux/arc/bits/syscalls.h b/libc/sysdeps/linux/arc/bits/syscalls.h
new file mode 100644
index 000000000..06d2cf926
--- /dev/null
+++ b/libc/sysdeps/linux/arc/bits/syscalls.h
@@ -0,0 +1,192 @@
+/*
+ * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Licensed under LGPL v2.1 or later, see the file COPYING.LIB in this tarball.
+ *
+ */
+#ifndef _BITS_SYSCALLS_H
+#define _BITS_SYSCALLS_H
+#ifndef _SYSCALL_H
+#error "Never use <bits/syscalls.h> directly; include <sys/syscall.h> instead."
+#endif
+
+#ifndef __ASSEMBLER__
+
+#include <errno.h>
+
+/*
+ * Fine tuned code for errno handling in syscall wrappers.
+ *
+ * 1. __syscall_error(raw_syscall_ret_val) is used to set the errno (vs.
+ *    the typical __set_errno). This helps elide the generated code for
+ *    GOT fetch for __errno_location pointer etc, in each wrapper.
+ *
+ * 2. The call to above is also disguised in inline asm. This elides
+ *    unconditional save/restore of a few callee regs which gcc almost
+ *    always generates if the call is exposed
+ *
+ * 3. The function can't be hidden because wrappers from librt et all also
+ *    call it. However hidden is not really needed to bypass PLT for
+ *    intra-libc calls as the branch insn w/o @plt is sufficient.
+ */
+
+#ifdef IS_IN_rtld
+/* ldso doesn't have real errno */
+#define ERRNO_ERRANDS(_sys_result)
+#else /* !IS_IN_rtld */
+extern int __syscall_error (int);
+#ifndef IS_IN_libc
+/* Inter-libc callers use PLT */
+#define CALL_ERRNO_SETTER   "bl   __syscall_error@plt    \n\t"
+#else
+/* intra-libc callers, despite PIC can bypass PLT */
+#define CALL_ERRNO_SETTER   "bl   __syscall_error    \n\t"
+#endif
+
+#define ERRNO_ERRANDS(_sys_result)          \
+        __asm__ volatile (                  \
+        "st.a blink, [sp, -4] \n\t"         \
+        CALL_ERRNO_SETTER                   \
+        "ld.ab blink, [sp, 4] \n\t"         \
+        :"+r" (_sys_result)                 \
+        :                                   \
+        :"r1","r2","r3","r4","r5","r6",     \
+         "r7","r8","r9","r10","r11","r12"   \
+        );
+
+#endif /* IS_IN_rtld */
+
+/* Invoke the syscall and return unprocessed kernel status */
+#define INTERNAL_SYSCALL(nm, err, nr, args...)		\
+	INTERNAL_SYSCALL_NCS(SYS_ify (nm), err, nr, args)
+
+/* -1 to -1023 as valid error values will suffice for some time */
+#define INTERNAL_SYSCALL_ERROR_P(val, err)		\
+	((unsigned int) (val) > (unsigned int) -1024)
+
+/*
+ * Standard sycall wrapper:
+ *  -"const" syscall number @nm, sets errno, return success/error-codes
+ */
+#define INLINE_SYSCALL(nm, nr_args, args...)				\
+({									\
+	register int __res __asm__("r0");				\
+	__res = INTERNAL_SYSCALL(nm, , nr_args, args);			\
+	if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P ((__res), ), 0))	\
+	{								\
+		ERRNO_ERRANDS(__res);					\
+	}								\
+	__res;								\
+})
+
+/* Non const syscall number @nm
+ * Ideally this could be folded within INLINE_SYSCALL with
+ * __builtin_constant_p in INTERNAL_SYSCALL but that fails for syscall.c
+ */
+#define INLINE_SYSCALL_NCS(nm, nr_args, args...)			\
+({									\
+	register int __res __asm__("r0");				\
+	__res = INTERNAL_SYSCALL_NCS(nm, , nr_args, args);		\
+	if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P ((__res), ), 0))	\
+	{								\
+		ERRNO_ERRANDS(__res);					\
+	}								\
+	__res;								\
+})
+
+#define INLINE_SYSCALL_NOERR(name, nr, args...)				   \
+  ({ unsigned int _inline_sys_result = INTERNAL_SYSCALL (name, , nr, args);\
+     (int) _inline_sys_result; })
+
+/*-------------------------------------------------------------------------
+ * Mechanics of Trap - specific to ARC700
+ *
+ * Note the memory clobber is not strictly needed for intended semantics of
+ * the inline asm. However some of the cases, such as old-style 6 arg mmap
+ * gcc was generating code for inline syscall ahead of buffer packing needed
+ * for syscall itself.
+ *-------------------------------------------------------------------------*/
+
+#define ARC_TRAP_INSN  "trap0	\n\t"
+
+#define INTERNAL_SYSCALL_NCS(nm, err, nr_args, args...)	\
+({							\
+	/* Per ABI, r0 is 1st arg and return reg */	\
+	register int __ret __asm__("r0");		\
+	register int _sys_num __asm__("r8");		\
+							\
+	LOAD_ARGS_##nr_args (nm, args)			\
+							\
+        __asm__ volatile (				\
+		ARC_TRAP_INSN				\
+		: "+r" (__ret)				\
+		: "r"(_sys_num) ASM_ARGS_##nr_args	\
+		: "memory");				\
+                                                        \
+	__ret;						\
+})
+
+/* Macros for setting up inline __asm__ input regs */
+#define ASM_ARGS_0
+#define ASM_ARGS_1	ASM_ARGS_0, "r" (__ret)
+#define ASM_ARGS_2	ASM_ARGS_1, "r" (_arg2)
+#define ASM_ARGS_3	ASM_ARGS_2, "r" (_arg3)
+#define ASM_ARGS_4	ASM_ARGS_3, "r" (_arg4)
+#define ASM_ARGS_5	ASM_ARGS_4, "r" (_arg5)
+#define ASM_ARGS_6	ASM_ARGS_5, "r" (_arg6)
+#define ASM_ARGS_7	ASM_ARGS_6, "r" (_arg7)
+
+/* Macros for converting sys-call wrapper args into sys call args */
+#define LOAD_ARGS_0(nm, arg)					\
+	_sys_num = (int) (nm);					\
+
+#define LOAD_ARGS_1(nm, arg1) 					\
+	__ret = (int) (arg1);					\
+	LOAD_ARGS_0 (nm, arg1)
+
+/*
+ * Note that the use of _tmpX might look superflous, however it is needed
+ * to ensure that register variables are not clobbered if arg happens to be
+ * a function call itself. e.g. sched_setaffinity() calling getpid() for arg2
+ *
+ * Also this specific order of recursive calling is important to segregate
+ * the tmp args evaluation (function call case described above) and assigment
+ * of register variables
+ */
+#define LOAD_ARGS_2(nm, arg1, arg2)				\
+	int _tmp2 = (int) (arg2);				\
+	LOAD_ARGS_1 (nm, arg1)					\
+	register int _arg2 __asm__ ("r1") = _tmp2;
+
+#define LOAD_ARGS_3(nm, arg1, arg2, arg3)			\
+	int _tmp3 = (int) (arg3);				\
+	LOAD_ARGS_2 (nm, arg1, arg2)				\
+	register int _arg3 __asm__ ("r2") = _tmp3;
+
+#define LOAD_ARGS_4(nm, arg1, arg2, arg3, arg4)			\
+	int _tmp4 = (int) (arg4);				\
+	LOAD_ARGS_3 (nm, arg1, arg2, arg3)			\
+	register int _arg4 __asm__ ("r3") = _tmp4;
+
+#define LOAD_ARGS_5(nm, arg1, arg2, arg3, arg4, arg5)		\
+	int _tmp5 = (int) (arg5);				\
+	LOAD_ARGS_4 (nm, arg1, arg2, arg3, arg4)		\
+	register int _arg5 __asm__ ("r4") = _tmp5;
+
+#define LOAD_ARGS_6(nm,  arg1, arg2, arg3, arg4, arg5, arg6)	\
+	int _tmp6 = (int) (arg6);				\
+	LOAD_ARGS_5 (nm, arg1, arg2, arg3, arg4, arg5)		\
+	register int _arg6 __asm__ ("r5") = _tmp6;
+
+#define LOAD_ARGS_7(nm, arg1, arg2, arg3, arg4, arg5, arg6, arg7)\
+	int _tmp7 = (int) (arg7);				\
+	LOAD_ARGS_6 (nm, arg1, arg2, arg3, arg4, arg5, arg6)	\
+	register int _arg7 __asm__ ("r6") = _tmp7;
+
+#else
+
+#define ARC_TRAP_INSN	trap0
+
+#endif /* __ASSEMBLER__ */
+
+#endif /* _BITS_SYSCALLS_H */