linux-kernel - Re: [PATCH v2 4/6] RISC-V: Detect unaligned vector accesses supported.

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Message-ID: <acb7a467-fc0e-4f32-8410-cd7aafce8bae@rivosinc.com>
Date: Fri, 14 Jun 2024 10:28:17 -0400
From: Jesse Taube <jesse@...osinc.com>
To: Conor Dooley <conor.dooley@...rochip.com>
Cc: linux-riscv@...ts.infradead.org, Jonathan Corbet <corbet@....net>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Conor Dooley <conor@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Clément Léger
 <cleger@...osinc.com>, Evan Green <evan@...osinc.com>,
 Andrew Jones <ajones@...tanamicro.com>,
 Charlie Jenkins <charlie@...osinc.com>, Xiao Wang <xiao.w.wang@...el.com>,
 Andy Chiu <andy.chiu@...ive.com>, Eric Biggers <ebiggers@...gle.com>,
 Greentime Hu <greentime.hu@...ive.com>, Björn Töpel
 <bjorn@...osinc.com>, Heiko Stuebner <heiko@...ech.de>,
 Costa Shulyupin <costa.shul@...hat.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Baoquan He <bhe@...hat.com>,
 Anup Patel <apatel@...tanamicro.com>, Zong Li <zong.li@...ive.com>,
 Sami Tolvanen <samitolvanen@...gle.com>,
 Ben Dooks <ben.dooks@...ethink.co.uk>,
 Alexandre Ghiti <alexghiti@...osinc.com>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>,
 Erick Archer <erick.archer@....com>, Joel Granados <j.granados@...sung.com>,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org
Subject: Re: [PATCH v2 4/6] RISC-V: Detect unaligned vector accesses
 supported.

On 6/14/24 04:40, Conor Dooley wrote:
> On Fri, Jun 14, 2024 at 09:36:55AM +0100, Conor Dooley wrote:
>> On Thu, Jun 13, 2024 at 03:16:13PM -0400, Jesse Taube wrote:
>>> --- a/arch/riscv/kernel/unaligned_access_speed.c
>>> +++ b/arch/riscv/kernel/unaligned_access_speed.c
>>> @@ -19,7 +19,8 @@
>>>   #define MISALIGNED_BUFFER_ORDER get_order(MISALIGNED_BUFFER_SIZE)
>>>   #define MISALIGNED_COPY_SIZE ((MISALIGNED_BUFFER_SIZE / 2) - 0x80)
>>>   
>>> -DEFINE_PER_CPU(long, misaligned_access_speed);
>>> +DEFINE_PER_CPU(long, misaligned_access_speed) = RISCV_HWPROBE_MISALIGNED_UNKNOWN;
>>> +DEFINE_PER_CPU(long, vector_misaligned_access) = RISCV_HWPROBE_VEC_MISALIGNED_UNSUPPORTED;
>>>   
>>>   #ifdef CONFIG_RISCV_PROBE_UNALIGNED_ACCESS
>>>   static cpumask_t fast_misaligned_access;
>>> @@ -268,12 +269,18 @@ static int check_unaligned_access_all_cpus(void)
>>>   
>>>   	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_ZICCLSM)) {
>>>   		for_each_online_cpu(cpu) {
>>> +#ifdef CONFIG_RISCV_VECTOR_MISALIGNED
>>> +			per_cpu(vector_misaligned_access, cpu) = RISCV_HWPROBE_VEC_MISALIGNED_FAST;
>>> +#endif
>>> +#ifdef CONFIG_RISCV_MISALIGNED
>>>   			per_cpu(misaligned_access_speed, cpu) = RISCV_HWPROBE_MISALIGNED_FAST;
>>> +#endif
>>
>> Can you IS_ENABLED()-ify these two as well please?
> 
> Ah, you can't cos the variable doesn't exist in the other case.

Yeah kinda just dealing with how it was originally written ideally we 
would use IS_ENABLED. I don't really want to have a 500+ diff patch
IS_ENABLED()-ifying the original code as well. I can do that if 
necessary though.

Thank,
Jesse Taube