linux-kernel - Re: [PATCH v2 1/7] powerpc/8xx: Fix vaddr for IMMR early remap

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-prev] [day] [month] [year] [list]

Message-ID: <792fb28c-f1fd-9242-a128-f6cfae8281e5@c-s.fr>
Date:	Tue, 17 May 2016 21:01:23 +0200
From:	christophe leroy <christophe.leroy@....fr>
To:	Scott Wood <oss@...error.net>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v2 1/7] powerpc/8xx: Fix vaddr for IMMR early remap



Le 17/05/2016 à 01:11, Scott Wood a écrit :
> On Fri, 2016-05-13 at 11:25 +0200, Christophe Leroy wrote:
>> Le 11/05/2016 à 22:38, Scott Wood a écrit :
>>> On Wed, 2016-05-11 at 17:03 +0200, Christophe Leroy wrote:
>>>> Memory: 124428K/131072K available (3748K kernel code, 188K rwdata,
>>>> 648K rodata, 508K init, 290K bss, 6644K reserved)
>>>> Kernel virtual memory layout:
>>>>     * 0xfffdf000..0xfffff000  : fixmap
>>>>     * 0xfde00000..0xfe000000  : consistent mem
>>>>     * 0xfddf6000..0xfde00000  : early ioremap
>>>>     * 0xc9000000..0xfddf6000  : vmalloc & ioremap
>>>> SLUB: HWalign=16, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
>>>>
>>>> Today, IMMR is mapped 1:1 at startup
>>>>
>>>> Mapping IMMR 1:1 is just wrong because it may overlap with another
>>>> area. On most mpc8xx boards it is OK as IMMR is set to 0xff000000
>>>> but for instance on EP88xC board, IMMR is at 0xfa200000 which
>>>> overlaps with VM ioremap area
>>>>
>>>> This patch fixes the virtual address for remapping IMMR with the fixmap
>>>> regardless of the value of IMMR.
>>>>
>>>> The size of IMMR area is 256kbytes (CPM at offset 0, security engine
>>>> at offset 128k) so a 512k page is enough
>>>>
>>>> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
>>>> ---
>>>> v2: No change
>>>>
>>>>    arch/powerpc/include/asm/fixmap.h |  7 +++++++
>>>>    arch/powerpc/kernel/asm-offsets.c |  8 ++++++++
>>>>    arch/powerpc/kernel/head_8xx.S    | 11 ++++++-----
>>>>    arch/powerpc/mm/mmu_decl.h        |  7 +++++++
>>>>    arch/powerpc/sysdev/cpm_common.c  | 15 ++++++++++++---
>>>>    5 files changed, 40 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/arch/powerpc/include/asm/fixmap.h
>>>> b/arch/powerpc/include/asm/fixmap.h
>>>> index 90f604b..4508b32 100644
>>>> --- a/arch/powerpc/include/asm/fixmap.h
>>>> +++ b/arch/powerpc/include/asm/fixmap.h
>>>> @@ -51,6 +51,13 @@ enum fixed_addresses {
>>>>    	FIX_KMAP_BEGIN,	/* reserved pte's for temporary kernel
>>>> mappings */
>>>>    	FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
>>>>    #endif
>>>> +#ifdef CONFIG_PPC_8xx
>>>> +	/* For IMMR we need an aligned 512K area */
>>>> +#define FIX_IMMR_SIZE	(512 * 1024 / PAGE_SIZE)
>>>> +	FIX_IMMR_START,
>>>> +	FIX_IMMR_BASE = __ALIGN_MASK(FIX_IMMR_START, FIX_IMMR_SIZE - 1)
>>>> - 1 +
>>>> +
>>>> +		       FIX_IMMR_SIZE,
>>>> +#endif
>>> What happens if FIX_IMMR_START is, for example, 0x100?  Then
>>> "__ALIGN_MASK(FIX_IMMR_START, FIX_IMMR_SIZE - 1) - 1" would be 0xff --
>>> you've
>>> gone backwards.  FIX_IMMR_BASE would be 0x17f, translating to an address
>>> of
>>> 0xffe80000.  IMMR would end at 0xfff00000.  The kmap range would begin at
>>> 0xffeff000 and you'd have an overlap.
>>>
>>> I think what you want is:
>>> 	FIX_IMMR_BASE = (FIX_IMMR_START & ~(FIX_IMMR_SIZE - 1)) +
>>> 			FIX_IMMR_SIZE - 1,
>>>
>> Why would the kmap range begin at 0xffeff000 ?
>> If FIX_IMMR_START is 0x100, this means FIX_KMAP_END is 0x0ff, so the
>> kmap range should begin at 0xfff00000, shouldn't it ?
> Yeah, I'm not sure what I was thinking in that reply in general.
>
>
I double checked with all possible values between 0 and FIX_IMMR_SIZE 
and didn't get any overlap. So I left it.
I submitted v3 of the patchset taking into account your other comments.

Christophe

---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
https://www.avast.com/antivirus