linux-kernel - generic page.h problem

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1300907573.15255.224.camel@deneb.localdomain>
Date:	Wed, 23 Mar 2011 15:12:53 -0400
From:	Mark Salter <msalter@...hat.com>
To:	arnd@...db.de
Cc:	linux-kernel@...r.kernel.org
Subject: generic page.h problem

I'm working with a new architecture port (nommu) and was wanting to use
the generic page.h but there is a problem. I'm using CONFIG_FLATMEM with
a non-zero CONFIG_KERNEL_RAM_BASE_ADDRESS. The hardware uses this same
address to access RAM from code and for DMA purposes. The generic page.h
has:

#ifdef CONFIG_KERNEL_RAM_BASE_ADDRESS
#define PAGE_OFFSET		(CONFIG_KERNEL_RAM_BASE_ADDRESS)
#else
#define PAGE_OFFSET		(0)
#endif

#ifndef __ASSEMBLY__

#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET))
#define __pa(x) ((unsigned long) (x) - PAGE_OFFSET)

The problem I have is that __va(x) and __pa(x) should do nothing on
this architecture. If I use the following, then everything seems to
work as it should.

diff --git a/include/asm-generic/page.h b/include/asm-generic/page.h
index 75fec18..4dc4a81 100644
--- a/include/asm-generic/page.h
+++ b/include/asm-generic/page.h
@@ -73,8 +73,8 @@ extern unsigned long memory_end;

 #ifndef __ASSEMBLY__

-#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET))
-#define __pa(x) ((unsigned long) (x) - PAGE_OFFSET)
+#define __va(x) ((void *)((unsigned long) (x)))
+#define __pa(x) ((unsigned long) (x))

 #define virt_to_pfn(kaddr)     (__pa(kaddr) >> PAGE_SHIFT)
 #define pfn_to_virt(pfn)       __va((pfn) << PAGE_SHIFT)

Am I missing something here? The only other arch using the generic
page.h is blackfin, but it uses a zero PAGE_OFFSET, so my patch
would have no effect there.

--Mark

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/