linux-kernel - Re: [PATCH] loongarch: Disable FIX_EARLYCON_MEM when ARCH

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

Message-Id: <05ac2a87-7f60-4336-a323-443967a77a76@app.fastmail.com>
Date: Fri, 03 Jan 2025 09:02:33 +0000
From: "Jiaxun Yang" <jiaxun.yang@...goat.com>
To: "Huacai Chen" <chenhuacai@...nel.org>
Cc: "Xuerui Wang" <kernel@...0n.name>, loongarch@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] loongarch: Disable FIX_EARLYCON_MEM when ARCH_IOREMAP is enabled



在2025年1月3日一月 上午2:38，Huacai Chen写道：
> Hi, Jiaxun,
>
> On Thu, Jan 2, 2025 at 10:34 PM Jiaxun Yang <jiaxun.yang@...goat.com> wrote:
>>
>> When ARCH_IOREMAP is enabled, we are using always accessible DMW
>> for ioremap. It makes no sense to create a dedicated mapping for
>> earlycon given that we can access the region via DMW.
>>
>> Disable FIX_EARLYCON_MEM when ARCH_IOREMAP is selected. This can
>> ease debugging for early mapping issues.
> Fixmap has nothing to do with IOREMAP, whether you use ARCH_IOREMAP or
> GENERIC_IOREMAP, earlycon is mapped by fixmap rather than ioremap().

When you have ARCH_IOREMAP it’s not necessary to create fixed map for earlycon.

As ioremap along is sufficient to access MMIO.

I’m doing this as it can help with debugging early mapping issues.

Thanks

>
> Huacai
>
>>
>> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
>> ---
>>  arch/loongarch/Kconfig              | 2 +-
>>  arch/loongarch/include/asm/fixmap.h | 2 ++
>>  2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>> index 1c4d13aa677e2e04b9791882fba7523f93d6a69d..ad8a8cf75343799ea626be52f521fa75e7cbe07b 100644
>> --- a/arch/loongarch/Kconfig
>> +++ b/arch/loongarch/Kconfig
>> @@ -246,7 +246,7 @@ config MACH_LOONGSON64
>>         def_bool 64BIT
>>
>>  config FIX_EARLYCON_MEM
>> -       def_bool y
>> +       def_bool !ARCH_IOREMAP
>>
>>  config PGTABLE_2LEVEL
>>         bool
>> diff --git a/arch/loongarch/include/asm/fixmap.h b/arch/loongarch/include/asm/fixmap.h
>> index d2e55ae55bb9c499b9a685509bc26d663054b58e..905dc7a5f9fa52ac924fe832749f39283c28a9f8 100644
>> --- a/arch/loongarch/include/asm/fixmap.h
>> +++ b/arch/loongarch/include/asm/fixmap.h
>> @@ -12,7 +12,9 @@
>>
>>  enum fixed_addresses {
>>         FIX_HOLE,
>> +#ifdef CONFIG_FIX_EARLYCON_MEM
>>         FIX_EARLYCON_MEM_BASE,
>> +#endif
>>         __end_of_fixed_addresses
>>  };
>>
>>
>> ---
>> base-commit: 8155b4ef3466f0e289e8fcc9e6e62f3f4dceeac2
>> change-id: 20250102-la-earlycon-fixed-map-d6a48bd5b831
>>
>> Best regards,
>> --
>> Jiaxun Yang <jiaxun.yang@...goat.com>
>>

-- 
- Jiaxun