Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v6 1/2] x86/delay: Fix the wrong asm constraint in `delay_loop()` | Date | Sun, 03 Apr 2022 19:14:34 +0200 |
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On Sun, Apr 03 2022 at 18:57, Thomas Gleixner wrote: > On Tue, Mar 29 2022 at 17:47, Ammar Faizi wrote: >> The asm constraint does not reflect that the asm statement can modify >> the value of @loops. But the asm statement in delay_loop() does modify >> the @loops. >> >> Specifiying the wrong constraint may lead to undefined behavior, it may >> clobber random stuff (e.g. local variable, important temporary value in >> regs, etc.). This is especially dangerous when the compiler decides to >> inline the function and since it doesn't know that the value gets >> modified, it might decide to use it from a register directly without >> reloading it.
Ignore me, I misread this part of the explanation.
Thanks,
tglx
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