From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 1 Jun 2012 02:22:52 +0000 (-0400)
Subject: alpha: rewrite kernel_execve in C
X-Git-Tag: next-20120724~4^2~9
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=68f596a7a0452ed96f65fecff1f714c3741e0662;p=karo-tx-linux.git

alpha: rewrite kernel_execve in C

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

diff --git a/arch/alpha/kernel/alpha_ksyms.c b/arch/alpha/kernel/alpha_ksyms.c
index d96e742d4dc2..b77b81389932 100644
--- a/arch/alpha/kernel/alpha_ksyms.c
+++ b/arch/alpha/kernel/alpha_ksyms.c
@@ -52,7 +52,6 @@ EXPORT_SYMBOL(alpha_write_fp_reg_s);
 
 /* entry.S */
 EXPORT_SYMBOL(kernel_thread);
-EXPORT_SYMBOL(kernel_execve);
 
 /* Networking helper routines. */
 EXPORT_SYMBOL(csum_tcpudp_magic);
diff --git a/arch/alpha/kernel/entry.S b/arch/alpha/kernel/entry.S
index 22b0c4d414a7..ec0da0567ab5 100644
--- a/arch/alpha/kernel/entry.S
+++ b/arch/alpha/kernel/entry.S
@@ -663,58 +663,6 @@ kernel_thread:
 	br	ret_to_kernel
 .end kernel_thread
 
-/*
- * kernel_execve(path, argv, envp)
- */
-	.align	4
-	.globl	kernel_execve
-	.ent	kernel_execve
-kernel_execve:
-	/* We can be called from a module.  */
-	ldgp	$gp, 0($27)
-	lda	$sp, -(32+SIZEOF_PT_REGS+8)($sp)
-	.frame	$sp, 32+SIZEOF_PT_REGS+8, $26, 0
-	stq	$26, 0($sp)
-	stq	$16, 8($sp)
-	stq	$17, 16($sp)
-	stq	$18, 24($sp)
-	.prologue 1
-
-	lda	$16, 32($sp)
-	lda	$17, 0
-	lda	$18, SIZEOF_PT_REGS
-	bsr	$26, memset		!samegp
-
-	/* Avoid the HAE being gratuitously wrong, which would cause us
-	   to do the whole turn off interrupts thing and restore it.  */
-	ldq	$2, alpha_mv+HAE_CACHE
-	stq	$2, 152+32($sp)
-
-	ldq	$16, 8($sp)
-	ldq	$17, 16($sp)
-	ldq	$18, 24($sp)
-	lda	$19, 32($sp)
-	bsr	$26, do_execve		!samegp
-
-	ldq	$26, 0($sp)
-	bne	$0, 1f			/* error! */
-
-	/* Move the temporary pt_regs struct from its current location
-	   to the top of the kernel stack frame.  See copy_thread for
-	   details for a normal process.  */
-	lda	$16, 0x4000 - SIZEOF_PT_REGS($8)
-	lda	$17, 32($sp)
-	lda	$18, SIZEOF_PT_REGS
-	bsr	$26, memmove		!samegp
-
-	/* Take that over as our new stack frame and visit userland!  */
-	lda	$sp, 0x4000 - SIZEOF_PT_REGS($8)
-	br	$31, ret_from_sys_call
-
-1:	lda	$sp, 32+SIZEOF_PT_REGS+8($sp)
-	ret
-.end 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 153d3fce3e8e..6251146f7fb5 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -455,3 +455,32 @@ 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) {
+		/*
+		 * 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...
+		 */
+		__asm__ __volatile__ (
+			"lda	$16, %0\n"
+			"lda	$17, %1\n"
+			"lda	$18, %2\n"
+			"bsr	$26, memmove\n"
+			"lda	$sp, %0\n"
+			"jsr	$31, ret_from_sys_call\n"
+			: : "m"(*current_pt_regs()), "m"(regs), "Ir"(sizeof(struct pt_regs)));
+	}
+	return err;
+}
+EXPORT_SYMBOL(kernel_execve);