From: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, hpa@zytor.com,
mingo@kernel.org, tglx@linutronix.de
Subject: Re: [PATCH 1/2] add helper for highmem checks
Date: Sat, 9 Feb 2013 10:41:21 +0100 [thread overview]
Message-ID: <20130209094121.GB17728@pd.tnic> (raw)
In-Reply-To: <20130208202813.62965F25@kernel.stglabs.ibm.com>
On Fri, Feb 08, 2013 at 12:28:13PM -0800, Dave Hansen wrote:
>
> Boris, could you check that this series also fixes the /dev/mem
> problem you were seeing?
>
> --
>
> We have a new debugging check on x86 that has caught a number
> of long-standing bugs. However, there is a _bit_ of collateral
> damage with things that call __pa(high_memory).
>
> We are now checking that any addresses passed to __pa() are
> *valid* and can be dereferenced.
>
> "high_memory", however, is not valid. It marks the start of
> highmem, and isn't itself a valid pointer. But, those users
> are really just asking "is this vaddr mapped"? So, give them
> a helper that does that, plus is also kind to our new
> debugging check.
>
>
> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
> ---
>
> linux-2.6.git-dave/arch/x86/mm/pat.c | 11 ++++++-----
> linux-2.6.git-dave/drivers/char/mem.c | 4 ++--
> linux-2.6.git-dave/drivers/mtd/mtdchar.c | 2 +-
> linux-2.6.git-dave/include/linux/mm.h | 13 +++++++++++++
> 4 files changed, 22 insertions(+), 8 deletions(-)
>
> diff -puN drivers/char/mem.c~clean-up-highmem-checks drivers/char/mem.c
> --- linux-2.6.git/drivers/char/mem.c~clean-up-highmem-checks 2013-02-08 08:42:37.291222110 -0800
> +++ linux-2.6.git-dave/drivers/char/mem.c 2013-02-08 12:27:27.837477867 -0800
> @@ -51,7 +51,7 @@ static inline unsigned long size_inside_
> #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
> static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
> {
> - return addr + count <= __pa(high_memory);
> + return !phys_addr_is_highmem(addr + count);
> }
>
> static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
> @@ -250,7 +250,7 @@ static int uncached_access(struct file *
> */
> if (file->f_flags & O_DSYNC)
> return 1;
> - return addr >= __pa(high_memory);
> + return phys_addr_is_highmem(addr);
> #endif
> }
> #endif
> diff -puN include/linux/mm.h~clean-up-highmem-checks include/linux/mm.h
> --- linux-2.6.git/include/linux/mm.h~clean-up-highmem-checks 2013-02-08 08:42:37.295222148 -0800
> +++ linux-2.6.git-dave/include/linux/mm.h 2013-02-08 09:01:49.758254468 -0800
> @@ -1771,5 +1771,18 @@ static inline unsigned int debug_guardpa
> static inline bool page_is_guard(struct page *page) { return false; }
> #endif /* CONFIG_DEBUG_PAGEALLOC */
>
> +static inline phys_addr_t last_lowmem_phys_addr(void)
> +{
> + /*
> + * 'high_memory' is not a pointer that can be dereferenced, so
> + * avoid calling __pa() on it directly.
> + */
> + return __pa(high_memory - 1);
> +}
> +static inline bool phys_addr_is_highmem(phys_addr_t addr)
> +{
> + return addr > last_lowmem_paddr();
I think you mean last_lowmem_phys_addr() here:
include/linux/mm.h: In function ‘phys_addr_is_highmem’:
include/linux/mm.h:1764:2: error: implicit declaration of function ‘last_lowmem_paddr’ [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1
Changed.
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
next prev parent reply other threads:[~2013-02-09 9:41 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-08 20:28 [PATCH 1/2] add helper for highmem checks Dave Hansen
2013-02-08 20:28 ` [PATCH 2/2] make /dev/kmem return error for highmem Dave Hansen
2013-02-08 20:48 ` H. Peter Anvin
2013-02-08 20:50 ` [PATCH 1/2] add helper for highmem checks H. Peter Anvin
2013-02-08 23:16 ` Dave Hansen
2013-02-09 9:41 ` Borislav Petkov [this message]
2013-02-09 10:47 ` Borislav Petkov
2013-02-11 17:32 ` Dave Hansen
2013-02-11 18:09 ` H. Peter Anvin
2013-02-11 18:28 ` Borislav Petkov
2013-02-11 19:44 ` H. Peter Anvin
2013-02-11 22:34 ` Borislav Petkov
2013-02-11 22:46 ` H. Peter Anvin
2013-02-11 23:00 ` Borislav Petkov
2013-02-11 23:02 ` H. Peter Anvin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130209094121.GB17728@pd.tnic \
--to=bp@alien8.de \
--cc=dave@linux.vnet.ibm.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mingo@kernel.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).