[LV] [PATCH] Permit 2- and 3-argument calls to open(2)

[Maciej W. Rozycki]

 All the other Linux platforms as well traditional *nix systems define the 
open(2) syscall as accepting either two or three arguments as needed.  
Make the debug argument-count verification code accept the syscall with 
either count as a special case.

Signed-off-by: Maciej W. Rozycki <macro at linux-mips.org>
---
 Please apply.

  Maciej

patch-mips-2.6.25-20080422-vax-open2-2
diff -up --recursive --new-file linux-mips-2.6.25-20080422.macro/arch/vax/kernel/syscall.c linux-mips-2.6.25-20080422/arch/vax/kernel/syscall.c
--- linux-mips-2.6.25-20080422.macro/arch/vax/kernel/syscall.c	2008-05-01 00:00:00.000000000 +0000
+++ linux-mips-2.6.25-20080422/arch/vax/kernel/syscall.c	2009-05-01 17:15:30.000000000 +0000
@@ -59,7 +59,7 @@ extern asmlinkage long sys_rt_sigaction(
 
 static struct {
 	unsigned long	*sc_func;
-	unsigned int	nr_args;
+	int		nr_args;
 } syscall[] = {
 #define SC(num, func, args)					\
 	[num] = {						\
@@ -70,7 +70,7 @@ static struct {
 	SC (__NR_fork,		sys_fork,		0),
 	SC (__NR_read,		sys_read,		3),
 	SC (__NR_write,		sys_write,		3),
-	SC (__NR_open,		sys_open,		3),
+	SC (__NR_open,		sys_open,		-1),
 	SC (__NR_close,		sys_close,		1),
 	SC (__NR_waitpid,	sys_waitpid,		3),
 	SC (__NR_creat,		sys_creat,		2),
@@ -271,7 +271,8 @@ void syscall_handler(struct pt_regs *reg
 {
 	unsigned int sc_number;
 	unsigned int *user_ap;
-	unsigned int nr_args;
+	int sc_args;
+	int nr_args;
 
 	sc_number = *(unsigned int *)(excep_info);
 
@@ -331,17 +332,26 @@ void syscall_handler(struct pt_regs *reg
 	/*
 	 * Check number of syscall arguments
 	 */
-	if (unlikely (syscall[sc_number].nr_args != nr_args)) {
-		printk (KERN_DEBUG "%s(%d): stack mismatch (should=%d, caller=%d) on syscall %d\n",
+	sc_args = syscall[sc_number].nr_args;
+	if (unlikely(sc_args != nr_args))
+		switch (sc_args) {
+		case -1:
+			/* open(2) is special and takes two or three args.  */
+			if (sc_number == __NR_open && (nr_args & ~1) == 2)
+				break;
+		/* Fall through.  */
+		default:
+			printk(KERN_DEBUG "%s(%d): stack mismatch "
+				"(should=%d, caller=%d) on syscall %d\n",
 				current->comm, current->pid,
-				syscall[sc_number].nr_args, nr_args, sc_number);
-		printk (KERN_DEBUG "Please report to "
+				sc_args, nr_args, sc_number);
+			printk(KERN_DEBUG "Please report to "
 				"<linux-vax at pergamentum.com>.\n");
 #ifdef CONFIG_DEBUG_VAX_CHECK_CHMx_ARGS_ABORT
-		regs->r0 = -EFAULT;
-		return;
+			regs->r0 = -EFAULT;
+			return;
 #endif /* CONFIG_DEBUG_VAX_CHECK_CHMx_ARGS_ABORT */
-	}
+		}
 #endif /* CONFIG_DEBUG_VAX_CHECK_CHMx_ARGS */
 
 	/*
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