linux-kernel - Re: [PATCHv9 13/16] x86/traps: Handle LASS thrown #SS

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Message-ID: <a76a41bd-7c0e-494d-bf4b-ace9e2230d34@intel.com>
Date: Thu, 10 Jul 2025 18:22:32 -0700
From: Sohil Mehta <sohil.mehta@...el.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
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Subject: Re: [PATCHv9 13/16] x86/traps: Handle LASS thrown #SS

On 7/9/2025 3:38 AM, Kirill A. Shutemov wrote:
> On Tue, Jul 08, 2025 at 10:12:28PM -0700, Sohil Mehta wrote:
>> On 7/7/2025 1:03 AM, Kirill A. Shutemov wrote:
>>
>>> +	hint = get_kernel_exc_address(regs, &exc_addr);
>>> +	if (hint != EXC_NO_HINT)
>>> +		printk(SSFSTR ", %s 0x%lx", kernel_exc_hint_help[hint], exc_addr);
>>> +
>>> +	if (hint != EXC_NON_CANONICAL)
>>> +		exc_addr = 0;
>>> +
>>> +	die_addr(SSFSTR, regs, error_code, exc_addr);
>>
>> I see a slight difference between the #GP handling and the #SS handling
>> here. For the #GP case, we seem to pass the hint string to die_addr().
>>
>> However, for the #SS, the hint is printed above and only SSFSTR gets
>> passed onto die_addr(). I am curious about the reasoning.
> 
> I hate how 'desc' size is defined in #GP handler:
> 
> 	char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR;
> 
> Too much voodoo to my liking. And it will overflow if any hint string is
> going to be longer than 50.
> 
> I don't want to repeat this magic for #SS.
> 

Thanks, that makes sense.

> I would argue we need to print directly in #GP handler as I do in #SS.
> But, IMO, it is outside of the scope of this patchset.
>