MIPS: Switch over to generic sys_execve and kernel_execve.

This version contains a few updates by David Daney, in particular it's
now using __builtin_frame_address() instead of asm() which depending
on personal taste, is slightly more appealing.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/ptrace.h

@@ -61,4 +61,10 @@ static inline void die_if_kernel(const char *str, struct pt_regs *regs)
 		die(str, regs);
 }
 
+#define current_pt_regs()						\
+({									\
+	unsigned long sp = (unsigned long)__builtin_frame_address(0);	\
+	(struct pt_regs *)((sp | (THREAD_SIZE - 1)) + 1 - 32) - 1;	\
+})
+
 #endif /* _ASM_PTRACE_H */

arch/mips/include/asm/unistd.h

@@ -18,8 +18,10 @@
 #ifndef __ASSEMBLY__
 
 #define __ARCH_OMIT_COMPAT_SYS_GETDENTS64
+#define __ARCH_WANT_KERNEL_EXECVE
 #define __ARCH_WANT_OLD_READDIR
 #define __ARCH_WANT_SYS_ALARM
+#define __ARCH_WANT_SYS_EXECVE
 #define __ARCH_WANT_SYS_GETHOSTNAME
 #define __ARCH_WANT_SYS_IPC
 #define __ARCH_WANT_SYS_PAUSE

arch/mips/kernel/entry.S

@@ -192,6 +192,15 @@ syscall_exit_work:
 	jal	syscall_trace_leave
 	b	resume_userspace
 
+LEAF(ret_from_kernel_execve)
+	move	sp, a0
+	ori	$28,  sp, _THREAD_SIZE - 1
+	xori	$28, $28, _THREAD_SIZE - 1
+	li	v0, 0
+	li	a3, 0
+	j	syscall_exit_partial
+	END(ret_from_kernel_execve)
+
 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_MIPS_MT)
 
 /*

arch/mips/kernel/linux32.c

@@ -3,7 +3,6 @@
  *
  * Copyright (C) 2000 Silicon Graphics, Inc.
  * Written by Ulf Carlsson (ulfc@engr.sgi.com)
- * sys32_execve from ia64/ia32 code, Feb 2000, Kanoj Sarcar (kanoj@sgi.com)
  */
 #include <linux/compiler.h>
 #include <linux/mm.h>
@@ -77,26 +76,6 @@ out:
 	return error;
 }
 
-/*
- * sys_execve() executes a new program.
- */
-asmlinkage int sys32_execve(nabi_no_regargs struct pt_regs regs)
-{
-	int error;
-	struct filename *filename;
-
-	filename = getname(compat_ptr(regs.regs[4]));
-	error = PTR_ERR(filename);
-	if (IS_ERR(filename))
-		goto out;
-	error = compat_do_execve(filename->name, compat_ptr(regs.regs[5]),
-				 compat_ptr(regs.regs[6]), &regs);
-	putname(filename);
-
-out:
-	return error;
-}
-
 #define RLIM_INFINITY32	0x7fffffff
 #define RESOURCE32(x) ((x > RLIM_INFINITY32) ? RLIM_INFINITY32 : x)
 

arch/mips/kernel/scall64-n32.S

@@ -167,7 +167,7 @@ EXPORT(sysn32_call_table)
 	PTR	sys_getsockopt
 	PTR	sys_clone			/* 6055 */
 	PTR	sys_fork
-	PTR	sys32_execve
+	PTR	compat_sys_execve
 	PTR	sys_exit
 	PTR	compat_sys_wait4
 	PTR	sys_kill			/* 6060 */

arch/mips/kernel/scall64-o32.S

@@ -203,7 +203,7 @@ sys_call_table:
 	PTR	sys_creat
 	PTR	sys_link
 	PTR	sys_unlink			/* 4010 */
-	PTR	sys32_execve
+	PTR	compat_sys_execve
 	PTR	sys_chdir
 	PTR	compat_sys_time
 	PTR	sys_mknod

arch/mips/kernel/syscall.c

@@ -127,28 +127,6 @@ _sys_clone(nabi_no_regargs struct pt_regs regs)
 	               parent_tidptr, child_tidptr);
 }
 
-/*
- * sys_execve() executes a new program.
- */
-asmlinkage int sys_execve(nabi_no_regargs struct pt_regs regs)
-{
-	int error;
-	struct filename *filename;
-
-	filename = getname((const char __user *) (long)regs.regs[4]);
-	error = PTR_ERR(filename);
-	if (IS_ERR(filename))
-		goto out;
-	error = do_execve(filename->name,
-			  (const char __user *const __user *) (long)regs.regs[5],
-	                  (const char __user *const __user *) (long)regs.regs[6],
-			  &regs);
-	putname(filename);
-
-out:
-	return error;
-}
-
 SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
 {
 	struct thread_info *ti = task_thread_info(current);
@@ -313,34 +291,3 @@ asmlinkage void bad_stack(void)
 {
 	do_exit(SIGSEGV);
 }
-
-/*
- * Do a system call from kernel instead of calling sys_execve so we
- * end up with proper pt_regs.
- */
-int kernel_execve(const char *filename,
-		  const char *const argv[],
-		  const char *const envp[])
-{
-	register unsigned long __a0 asm("$4") = (unsigned long) filename;
-	register unsigned long __a1 asm("$5") = (unsigned long) argv;
-	register unsigned long __a2 asm("$6") = (unsigned long) envp;
-	register unsigned long __a3 asm("$7");
-	unsigned long __v0;
-
-	__asm__ volatile ("					\n"
-	"	.set	noreorder				\n"
-	"	li	$2, %5		# __NR_execve		\n"
-	"	syscall						\n"
-	"	move	%0, $2					\n"
-	"	.set	reorder					\n"
-	: "=&r" (__v0), "=r" (__a3)
-	: "r" (__a0), "r" (__a1), "r" (__a2), "i" (__NR_execve)
-	: "$2", "$8", "$9", "$10", "$11", "$12", "$13", "$14", "$15", "$24",
-	  "memory");
-
-	if (__a3 == 0)
-		return __v0;
-
-	return -__v0;
-}