mips: switch to generic sys_fork() and sys_clone()

we still need the wrappers to store callee-saved registers in
pt_regs, but once that done we can jump to kernel/fork.c variants.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/mips/Kconfig

@@ -41,6 +41,7 @@ config MIPS
 	select HAVE_MOD_ARCH_SPECIFIC
 	select MODULES_USE_ELF_REL if MODULES
 	select MODULES_USE_ELF_RELA if MODULES && 64BIT
+	select CLONE_BACKWARDS
 	select GENERIC_SIGALTSTACK
 	select GENERIC_COMPAT_RT_SIGACTION
 	select GENERIC_COMPAT_RT_SIGQUEUEINFO

arch/mips/include/asm/sim.h

@@ -20,10 +20,10 @@
 #define save_static_function(symbol)					\
 __asm__(								\
 	".text\n\t"							\
-	".globl\t" #symbol "\n\t"					\
+	".globl\t__" #symbol "\n\t"					\
 	".align\t2\n\t"							\
-	".type\t" #symbol ", @function\n\t"				\
-	".ent\t" #symbol ", 0\n"					\
+	".type\t__" #symbol ", @function\n\t"				\
+	".ent\t__" #symbol ", 0\n__"					\
 	#symbol":\n\t"							\
 	".frame\t$29, 0, $31\n\t"					\
 	"sw\t$16,"__str(PT_R16)"($29)\t\t\t# save_static_function\n\t"	\
@@ -35,9 +35,9 @@ __asm__(								\
 	"sw\t$22,"__str(PT_R22)"($29)\n\t"				\
 	"sw\t$23,"__str(PT_R23)"($29)\n\t"				\
 	"sw\t$30,"__str(PT_R30)"($29)\n\t"				\
-	"j\t_" #symbol "\n\t"						\
-	".end\t" #symbol "\n\t"						\
-	".size\t" #symbol",. - " #symbol)
+	"j\t" #symbol "\n\t"						\
+	".end\t__" #symbol "\n\t"					\
+	".size\t__" #symbol",. - __" #symbol)
 
 #define nabi_no_regargs
 
@@ -48,10 +48,10 @@ __asm__(								\
 #define save_static_function(symbol)					\
 __asm__(								\
 	".text\n\t"							\
-	".globl\t" #symbol "\n\t"					\
+	".globl\t__" #symbol "\n\t"					\
 	".align\t2\n\t"							\
-	".type\t" #symbol ", @function\n\t"				\
-	".ent\t" #symbol ", 0\n"					\
+	".type\t__" #symbol ", @function\n\t"				\
+	".ent\t__" #symbol ", 0\n__"					\
 	#symbol":\n\t"							\
 	".frame\t$29, 0, $31\n\t"					\
 	"sd\t$16,"__str(PT_R16)"($29)\t\t\t# save_static_function\n\t"	\
@@ -63,9 +63,9 @@ __asm__(								\
 	"sd\t$22,"__str(PT_R22)"($29)\n\t"				\
 	"sd\t$23,"__str(PT_R23)"($29)\n\t"				\
 	"sd\t$30,"__str(PT_R30)"($29)\n\t"				\
-	"j\t_" #symbol "\n\t"						\
-	".end\t" #symbol "\n\t"						\
-	".size\t" #symbol",. - " #symbol)
+	"j\t" #symbol "\n\t"						\
+	".end\t__" #symbol "\n\t"					\
+	".size\t__" #symbol",. - __" #symbol)
 
 #define nabi_no_regargs							\
 	unsigned long __dummy0,						\

arch/mips/include/asm/unistd.h

@@ -43,6 +43,8 @@
 # ifdef CONFIG_MIPS32_O32
 #  define __ARCH_WANT_COMPAT_SYS_TIME
 # endif
+#define __ARCH_WANT_SYS_FORK
+#define __ARCH_WANT_SYS_CLONE
 
 /* whitelists for checksyscalls */
 #define __IGNORE_select

arch/mips/kernel/linux32.c

@@ -279,25 +279,6 @@ asmlinkage long sys32_fallocate(int fd, int mode, unsigned offset_a2,
 	                     merge_64(len_a4, len_a5));
 }
 
-save_static_function(sys32_clone);
-static int noinline __used
-_sys32_clone(nabi_no_regargs struct pt_regs regs)
-{
-	unsigned long clone_flags;
-	unsigned long newsp;
-	int __user *parent_tidptr, *child_tidptr;
-
-	clone_flags = regs.regs[4];
-	newsp = regs.regs[5];
-	parent_tidptr = (int __user *) regs.regs[6];
-
-	/* Use __dummy4 instead of getting it off the stack, so that
-	   syscall() works.  */
-	child_tidptr = (int __user *) __dummy4;
-	return do_fork(clone_flags, newsp, 0,
-	               parent_tidptr, child_tidptr);
-}
-
 asmlinkage long sys32_lookup_dcookie(u32 a0, u32 a1, char __user *buf,
 	size_t len)
 {

arch/mips/kernel/scall32-o32.S

@@ -226,7 +226,7 @@ einval:	li	v0, -ENOSYS
 	.macro	syscalltable
 	sys	sys_syscall		8	/* 4000 */
 	sys	sys_exit		1
-	sys	sys_fork		0
+	sys	__sys_fork		0
 	sys	sys_read		3
 	sys	sys_write		3
 	sys	sys_open		3	/* 4005 */
@@ -344,7 +344,7 @@ einval:	li	v0, -ENOSYS
 	sys	sys_ipc			6
 	sys	sys_fsync		1
 	sys	sys_sigreturn		0
-	sys	sys_clone		0	/* 4120 */
+	sys	__sys_clone		6	/* 4120 */
 	sys	sys_setdomainname	2
 	sys	sys_newuname		1
 	sys	sys_ni_syscall		0	/* sys_modify_ldt */

arch/mips/kernel/scall64-64.S

@@ -170,8 +170,8 @@ sys_call_table:
 	PTR	sys_socketpair
 	PTR	sys_setsockopt
 	PTR	sys_getsockopt
-	PTR	sys_clone			/* 5055 */
-	PTR	sys_fork
+	PTR	__sys_clone			/* 5055 */
+	PTR	__sys_fork
 	PTR	sys_execve
 	PTR	sys_exit
 	PTR	sys_wait4

arch/mips/kernel/scall64-n32.S

@@ -159,8 +159,8 @@ EXPORT(sysn32_call_table)
 	PTR	sys_socketpair
 	PTR	compat_sys_setsockopt
 	PTR	sys_getsockopt
-	PTR	sys_clone			/* 6055 */
-	PTR	sys_fork
+	PTR	__sys_clone			/* 6055 */
+	PTR	__sys_fork
 	PTR	compat_sys_execve
 	PTR	sys_exit
 	PTR	compat_sys_wait4

arch/mips/kernel/scall64-o32.S

@@ -194,7 +194,7 @@ einval:	li	v0, -ENOSYS
 sys_call_table:
 	PTR	sys32_syscall			/* 4000 */
 	PTR	sys_exit
-	PTR	sys_fork
+	PTR	__sys_fork
 	PTR	sys_read
 	PTR	sys_write
 	PTR	compat_sys_open			/* 4005 */
@@ -312,7 +312,7 @@ sys_call_table:
 	PTR	sys_32_ipc
 	PTR	sys_fsync
 	PTR	sys32_sigreturn
-	PTR	sys32_clone			/* 4120 */
+	PTR	__sys_clone			/* 4120 */
 	PTR	sys_setdomainname
 	PTR	sys_newuname
 	PTR	sys_ni_syscall			/* sys_modify_ldt */

arch/mips/kernel/syscall.c

@@ -83,41 +83,7 @@ SYSCALL_DEFINE6(mips_mmap2, unsigned long, addr, unsigned long, len,
 }
 
 save_static_function(sys_fork);
-static int __used noinline
-_sys_fork(nabi_no_regargs struct pt_regs regs)
-{
-	return do_fork(SIGCHLD, 0, 0, NULL, NULL);
-}
-
 save_static_function(sys_clone);
-static int __used noinline
-_sys_clone(nabi_no_regargs struct pt_regs regs)
-{
-	unsigned long clone_flags;
-	unsigned long newsp;
-	int __user *parent_tidptr, *child_tidptr;
-
-	clone_flags = regs.regs[4];
-	newsp = regs.regs[5];
-	parent_tidptr = (int __user *) regs.regs[6];
-#ifdef CONFIG_32BIT
-	/* We need to fetch the fifth argument off the stack.  */
-	child_tidptr = NULL;
-	if (clone_flags & (CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID)) {
-		int __user *__user *usp = (int __user *__user *) regs.regs[29];
-		if (regs.regs[2] == __NR_syscall) {
-			if (get_user (child_tidptr, &usp[5]))
-				return -EFAULT;
-		}
-		else if (get_user (child_tidptr, &usp[4]))
-			return -EFAULT;
-	}
-#else
-	child_tidptr = (int __user *) regs.regs[8];
-#endif
-	return do_fork(clone_flags, newsp, 0,
-	               parent_tidptr, child_tidptr);
-}
 
 SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
 {