From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 1 Jun 2012 02:22:52 +0000 (-0400)
Subject: alpha: introduce ret_from_kernel_execve(), switch to generic kernel_execve()
X-Git-Tag: next-20120910~4^2~31
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=386e1c739c80490c756820e24414ed25621c8f6f;p=karo-tx-linux.git

alpha: introduce ret_from_kernel_execve(), switch to generic kernel_execve()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/arch/alpha/include/asm/unistd.h b/arch/alpha/include/asm/unistd.h
index 7826e227e4d0..3cb6c1188984 100644
--- a/arch/alpha/include/asm/unistd.h
+++ b/arch/alpha/include/asm/unistd.h
@@ -482,6 +482,7 @@
 #define __ARCH_WANT_SYS_SIGPENDING
 #define __ARCH_WANT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_SYS_EXECVE
+#define __ARCH_WANT_KERNEL_EXECVE
 
 /* "Conditional" syscalls.  What we want is
 
diff --git a/arch/alpha/kernel/entry.S b/arch/alpha/kernel/entry.S
index 61ff145cab6e..c89dff82375e 100644
--- a/arch/alpha/kernel/entry.S
+++ b/arch/alpha/kernel/entry.S
@@ -663,6 +663,31 @@ kernel_thread:
 	br	ret_to_kernel
 .end kernel_thread
 
+	.globl	ret_from_kernel_execve
+	.align	4
+	.ent	ret_from_kernel_execve
+ret_from_kernel_execve:
+	/*
+	 * copy regs to normal position and off to userland we go...
+	 * note that we are not guaranteed that we are deep enough
+	 * in stack for current_pt_regs() not to overlap our stack
+	 * frame; memcpy() would not be safe and we _must_ do
+	 * everything starting from that memmove() in assembler.
+	 * And we can't mangle $sp until after the call of memmove()
+	 * either...
+	 */
+	lda	$18, SIZEOF_PT_REGS
+	bsr	$26, memmove            !samegp
+
+	/* Take that over as our new stack frame and visit userland!  */
+	mov	$0, $sp
+	/* Avoid the HAE being gratuitously wrong, to avoid restoring it.  */
+	ldq	$2, alpha_mv+HAE_CACHE
+	stq	$2, 152($sp)		/* HAE */
+	br	$31, ret_to_user
+
+.end	ret_from_kernel_execve
+
 
 /*
  * Special system calls.  Most of these are special in that they either
diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index 145473909199..948094543b8a 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -434,22 +434,3 @@ get_wchan(struct task_struct *p)
 	}
 	return pc;
 }
-
-int kernel_execve(const char *path, const char *const argv[], const char *const envp[])
-{
-	/* Avoid the HAE being gratuitously wrong, which would cause us
-	   to do the whole turn off interrupts thing and restore it.  */
-	struct pt_regs regs = {.hae = alpha_mv.hae_cache};
-	int err = do_execve(path, argv, envp, &regs);
-	if (!err) {
-		struct pt_regs *p = current_pt_regs();
-		/* copy regs to normal position and off to userland we go... */
-		*p = regs;
-		__asm__ __volatile__ (
-			"mov	%0, $sp;"
-			"br	$31, ret_from_sys_call"
-			: : "r"(p));
-	}
-	return err;
-}
-EXPORT_SYMBOL(kernel_execve);