linux-kernel - Re: [PATCH v3 5/5] rust: Add warn_on and warn_on

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Message-Id: <20250305.141307.586794213367343251.fujita.tomonori@gmail.com>
Date: Wed, 05 Mar 2025 14:13:07 +0900 (JST)
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: aliceryhl@...gle.com
Cc: fujita.tomonori@...il.com, linux-kernel@...r.kernel.org,
 rust-for-linux@...r.kernel.org, x86@...nel.org,
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Subject: Re: [PATCH v3 5/5] rust: Add warn_on and warn_on_once

On Mon, 3 Mar 2025 14:33:39 +0100
Alice Ryhl <aliceryhl@...gle.com> wrote:

>> +#[macro_export]
>> +#[doc(hidden)]
>> +#[cfg(all(CONFIG_BUG, not(CONFIG_UML)))]
>> +macro_rules! warn_flags {
>> +    ($flags:expr) => {
>> +        const FLAGS: u32 = $crate::bindings::BUGFLAG_WARNING | $flags;
>> +        // SAFETY: Just an FFI call.
>> +        #[cfg(CONFIG_DEBUG_BUGVERBOSE)]
>> +        unsafe {
>> +            $crate::asm!(concat!(
>> +                "/* {size} */",
>> +                ".pushsection .rodata.str1.1, \"aMS\",@progbits, 1\n",
>> +                "111:\t .string ", "\"", file!(), "\"\n",
>> +                ".popsection\n",
> 
> It looks like you're doing this so that you can reference the filename
> with "111b", but could you do this instead:
> 
> const _FILE: &[u8] = file!().as_bytes();
> // Plus one for nul-terminator.
> static FILE: [u8; 1 + _FILE.len()] = {
>     let mut bytes = [0; 1 + _FILE.len()];
>     let mut i = 0;
>     while i < _FILE.len() {
>         bytes[i] = _FILE[i];
>         i += 1;
>     }
>     bytes
> };

Neat! I will use this in the next version.

> and then use
> 
> asm!(
>     concat!(
>         "/* {size} */",
>         include!(concat!(env!("OBJTREE"),
> "/rust/kernel/generated_arch_warn_asm.rs")),
>         include!(concat!(env!("OBJTREE"),
> "/rust/kernel/generated_arch_reachable_asm.rs")));
>     file = sym FILE,
>     line = const line!(),
>     ...
> );
> 
> with
> ::kernel::concat_literals!(ARCH_WARN_ASM("{file}", "{line}",
> "{flags}", "{size}")),
> 
> That would be a lot simpler to understand than what you are doing.

Indeed.

Thanks a lot!