Re: [PATCH v3 3/5] RISC-V: Improve init_resources

From: Nick Kossifidis <mick@ics.forth.gr>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Nick Kossifidis <mick@ics.forth.gr>,
	linux-riscv <linux-riscv@lists.infradead.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 3/5] RISC-V: Improve init_resources
Date: Tue, 06 Apr 2021 11:11:22 +0300	[thread overview]
Message-ID: <5a09d1f0ded4581c9e7458f546db9329@mailhost.ics.forth.gr> (raw)
In-Reply-To: <CAMuHMdWi+wo0+PCR6B1wyXVesG-kL9NQt8XFBuWhZ3SdVUaLZg@mail.gmail.com>

Hello Geert,

Στις 2021-04-06 10:19, Geert Uytterhoeven έγραψε:
> Hi Nick,
> 
> Thanks for your patch!
> 
> On Mon, Apr 5, 2021 at 10:57 AM Nick Kossifidis <mick@ics.forth.gr> 
> wrote:
>> * Kernel region is always present and we know where it is, no
>> need to look for it inside the loop, just ignore it like the
>> rest of the reserved regions within system's memory.
>> 
>> * Don't call memblock_free inside the loop, if called it'll split
>> the region of pre-allocated resources in two parts, messing things
>> up, just re-use the previous pre-allocated resource and free any
>> unused resources after both loops finish.
>> 
>> * memblock_alloc may add a region when called, so increase the
>> number of pre-allocated regions by one to be on the safe side
>> (reported and patched by Geert Uytterhoeven)
>> 
>> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> 
> Where does this SoB come from?
> 
>> Signed-off-by: Nick Kossifidis <mick@ics.forth.gr>
> 
>> --- a/arch/riscv/kernel/setup.c
>> +++ b/arch/riscv/kernel/setup.c
> 
>> @@ -129,53 +139,42 @@ static void __init init_resources(void)
>>         struct resource *res = NULL;
>>         struct resource *mem_res = NULL;
>>         size_t mem_res_sz = 0;
>> -       int ret = 0, i = 0;
>> -
>> -       code_res.start = __pa_symbol(_text);
>> -       code_res.end = __pa_symbol(_etext) - 1;
>> -       code_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> -
>> -       rodata_res.start = __pa_symbol(__start_rodata);
>> -       rodata_res.end = __pa_symbol(__end_rodata) - 1;
>> -       rodata_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> -
>> -       data_res.start = __pa_symbol(_data);
>> -       data_res.end = __pa_symbol(_edata) - 1;
>> -       data_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> +       int num_resources = 0, res_idx = 0;
>> +       int ret = 0;
>> 
>> -       bss_res.start = __pa_symbol(__bss_start);
>> -       bss_res.end = __pa_symbol(__bss_stop) - 1;
>> -       bss_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> +       /* + 1 as memblock_alloc() might increase 
>> memblock.reserved.cnt */
>> +       num_resources = memblock.memory.cnt + memblock.reserved.cnt + 
>> 1;
>> +       res_idx = num_resources - 1;
>> 
>> -       mem_res_sz = (memblock.memory.cnt + memblock.reserved.cnt) * 
>> sizeof(*mem_res);
> 
> Oh, you incorporated my commit ce989f1472ae350e ("RISC-V: Fix 
> out-of-bounds
> accesses in init_resources()") (from v5.12-rc4) into your patch.
> Why? This means your patch does not apply against upstream.
> 

Sorry if this looks awkward, I'm under the impression that new features 
go on for-next instead of fixes and your patch hasn't been merged on 
for-next yet. I thought it would be cleaner to have one patch to merge 
for init_resources instead of two, and simpler for people to test the 
series. I can rebase this on top of fixes if that works better for you 
or Palmer.

Regards,
Nick