Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 21 Nov 2019 09:51:03 -0800 | Subject | Re: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter |
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On Thu, Nov 21, 2019 at 9:43 AM David Laight <David.Laight@aculab.com> wrote: > > From: Ingo Molnar > > Sent: 21 November 2019 17:12 > > * Peter Zijlstra <peterz@infradead.org> wrote: > ... > > > This feature MUST be default enabled, otherwise everything will > > > be/remain broken and we'll end up in the situation where you can't use > > > it even if you wanted to. > > > > Agreed. > > Before it can be enabled by default someone needs to go through the > kernel and fix all the code that abuses the 'bit' functions by using them > on int[] instead of long[]. > > I've only seen one fix go through for one use case of one piece of code > that repeatedly uses potentially misaligned int[] arrays for bitmasks. >
Can we really not just change the lock asm to use 32-bit accesses for set_bit(), etc? Sure, it will fail if the bit index is greater than 2^32, but that seems nuts.
(Why the *hell* do the bitops use long anyway? They're *bit masks* for crying out loud. As in, users generally want to operate on fixed numbers of bits.)
--Andy
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