linux-kernel - [PATCH] FRV: Fix kernel/user segment handling in NOMMU mode

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Message-ID: <20100324171217.11089.15339.stgit@warthog.procyon.org.uk>
Date:	Wed, 24 Mar 2010 17:12:17 +0000
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>
Subject: [PATCH] FRV: Fix kernel/user segment handling in NOMMU mode

In NOMMU mode, the FRV segment handling is broken because KERNEL_DS == USER_DS.
This causes tests of the following sort:

	/* don't pin down non-user-based iovecs */
	if (segment_eq(get_fs(), KERNEL_DS))
		return NULL;

to malfunction.

To fix this, make USER_DS the top of RAM instead of the top of the non-IO
address space, and make KERNEL_DS one more than the top of the non-IO address
space.

Also get rid of FRV's __addr_ok() as nothing uses it.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 arch/frv/include/asm/segment.h |    6 +++---
 arch/frv/include/asm/uaccess.h |    2 --
 2 files changed, 3 insertions(+), 5 deletions(-)


diff --git a/arch/frv/include/asm/segment.h b/arch/frv/include/asm/segment.h
index e3616a6..a2320a4 100644
--- a/arch/frv/include/asm/segment.h
+++ b/arch/frv/include/asm/segment.h
@@ -21,12 +21,12 @@ typedef struct {
 
 #define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
 
-#define KERNEL_DS		MAKE_MM_SEG(0xdfffffffUL)
-
 #ifdef CONFIG_MMU
 #define USER_DS			MAKE_MM_SEG(TASK_SIZE - 1)
+#define KERNEL_DS		MAKE_MM_SEG(0xdfffffffUL)
 #else
-#define USER_DS			KERNEL_DS
+#define USER_DS			MAKE_MM_SEG(memory_end)
+#define KERNEL_DS		MAKE_MM_SEG(0xe0000000UL)
 #endif
 
 #define get_ds()		(KERNEL_DS)
diff --git a/arch/frv/include/asm/uaccess.h b/arch/frv/include/asm/uaccess.h
index 53650c9..0b67ec5 100644
--- a/arch/frv/include/asm/uaccess.h
+++ b/arch/frv/include/asm/uaccess.h
@@ -27,8 +27,6 @@
 #define VERIFY_READ	0
 #define VERIFY_WRITE	1
 
-#define __addr_ok(addr) ((unsigned long)(addr) < get_addr_limit())
-
 /*
  * check that a range of addresses falls within the current address limit
  */

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