linux-kernel - RE: [????] [PATCH v2] x86/math64: handle #DE in mul_u64_u64_div

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Message-ID: <013ffed7ba224294a69befe91cb3ceec@baidu.com>
Date: Wed, 30 Jul 2025 02:30:04 +0000
From: "Li,Rongqing" <lirongqing@...du.com>
To: Oleg Nesterov <oleg@...hat.com>, David Laight
	<david.laight.linux@...il.com>, "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar
	<mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>
CC: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
	"Dave Hansen" <dave.hansen@...ux.intel.com>, Steven Rostedt
	<rostedt@...dmis.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "x86@...nel.org" <x86@...nel.org>
Subject: RE: [????] [PATCH v2] x86/math64: handle #DE in mul_u64_u64_div_u64()



> Change mul_u64_u64_div_u64() to return ULONG_MAX if the result doesn't fit
> into u64 or div == 0. The former matches the generic implementation in
> lib/math/div64.c, the latter doesn't. Perhaps we will add a WARN() into the
> fixup_exception() paths later.
> 
> No need to use _ASM_EXTABLE_TYPE_REG(), we know that the target register
> is pt_regs->ax with offset == 0, so a simple EX_DATA_REG(0) should work just
> fine.
> 
> Reported-by: Li RongQing <lirongqing@...du.com>
> Link:
> https://lore.kernel.org/all/78a0d7bb20504c0884d474868eccd858@baidu.com/
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---

Tested-by: Li RongQing <lirongqing@...du.com>

Thanks for fixing

Br