linux-kernel - Re: [PATCH v2 4/6] arm64: Utilize phys_initrd_start/phys_initrd

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]

Date:   Wed, 31 Oct 2018 10:33:08 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Mike Rapoport <rppt@...ux.ibm.com>
Cc:     linux-kernel@...r.kernel.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Robin Murphy <robin.murphy@....com>,
        Laura Abbott <labbott@...hat.com>,
        Stefan Agner <stefan@...er.ch>,
        Johannes Weiner <hannes@...xchg.org>,
        Greg Hackmann <ghackmann@...roid.com>,
        Kristina Martsenko <kristina.martsenko@....com>,
        CHANDAN VN <chandan.vn@...sung.com>,
        "moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
        <devicetree@...r.kernel.org>, linux@...linux.org.uk,
        green.hu@...il.com, deanbo422@...il.com, gxt@....edu.cn,
        ard.biesheuvel@...aro.org, linux-snps-arc@...ts.infradead.org,
        vgupta@...opsys.com
Subject: Re: [PATCH v2 4/6] arm64: Utilize phys_initrd_start/phys_initrd_size

On 10/31/18 12:03 AM, Mike Rapoport wrote:
> On Tue, Oct 30, 2018 at 04:07:19PM -0700, Florian Fainelli wrote:
>> ARM64 is the only architecture that re-defines
>> __early_init_dt_declare_initrd() in order for that function to populate
>> initrd_start/initrd_end with physical addresses instead of virtual
>> addresses. Instead of having an override we can leverage
>> drivers/of/fdt.c populating phys_initrd_start/phys_initrd_size to
>> populate those variables for us.
>>
>> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
>> ---
>>  arch/arm64/mm/init.c | 21 +++++++++------------
>>  1 file changed, 9 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index 3cf87341859f..e95cee656a55 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -72,8 +72,8 @@ static int __init early_initrd(char *p)
>>  	if (*endp == ',') {
>>  		size = memparse(endp + 1, NULL);
>>  
>> -		initrd_start = start;
>> -		initrd_end = start + size;
>> +		phys_initrd_start = start;
>> +		phys_initrd_size = size;
>>  	}
>>  	return 0;
>>  }
>> @@ -408,14 +408,14 @@ void __init arm64_memblock_init(void)
>>  		memblock_add(__pa_symbol(_text), (u64)(_end - _text));
>>  	}
>>  
>> -	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
>> +	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
>>  		/*
>>  		 * Add back the memory we just removed if it results in the
>>  		 * initrd to become inaccessible via the linear mapping.
>>  		 * Otherwise, this is a no-op
>>  		 */
>> -		u64 base = initrd_start & PAGE_MASK;
>> -		u64 size = PAGE_ALIGN(initrd_end) - base;
>> +		u64 base = phys_initrd_start & PAGE_MASK;
>> +		u64 size = PAGE_ALIGN(phys_initrd_size);
>>  
>>  		/*
>>  		 * We can only add back the initrd memory if we don't end up
>> @@ -460,13 +460,10 @@ void __init arm64_memblock_init(void)
>>  	 */
>>  	memblock_reserve(__pa_symbol(_text), _end - _text);
>>  #ifdef CONFIG_BLK_DEV_INITRD
>> -	if (initrd_start) {
> 
> There may be no initrd at all, so the condition here would rather become
> 
> 	if (phys_initrd_start)

Or use phys_initrd_size, which would be consistent with how other
architectures typically test for this.

> 
>> -		memblock_reserve(initrd_start, initrd_end - initrd_start);
>> -
>> -		/* the generic initrd code expects virtual addresses */
>> -		initrd_start = __phys_to_virt(initrd_start);
>> -		initrd_end = __phys_to_virt(initrd_end);
>> -	}
>> +	/* the generic initrd code expects virtual addresses */
>> +	initrd_start = __phys_to_virt(phys_initrd_start);
>> +	initrd_end = initrd_start + phys_initrd_size;
>> +	initrd_below_start_ok = 0;
>>  #endif
> 
> I also wonder what is the reason to keep memstart_addr randomization and
> initrd setup interleaved?
> 
> What we have now is roughly:
> 
> 1) set memstart_addr
> 2) enforce memory_limit
> 3) reserve initrd
> 4) randomize memstart_addr
> 5) reserve text + data
> 6) reserve initrd again and set virtual addresses of initrd_{start,end}
> 
> Maybe it's possible to merge (3) into (6) ?

That's kind of orthogonal to this patch series, but it's a valid
question, not sure I would want to tackle that just now though :)
-- 
Florian