Messages in this thread | | | Date | Wed, 13 May 2020 20:41:48 -0400 (EDT) | From | Mathieu Desnoyers <> | Subject | Re: [patch V4 part 3 01/29] x86/traps: Mark fixup_bad_iret() noinstr |
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----- On May 12, 2020, at 9:51 PM, rostedt rostedt@goodmis.org wrote:
> On Fri, 8 May 2020 17:39:00 -0700 > Andy Lutomirski <luto@kernel.org> wrote: > >> On Tue, May 5, 2020 at 7:15 AM Thomas Gleixner <tglx@linutronix.de> wrote: >> > >> > This is called from deep entry ASM in a situation where instrumentation >> > will cause more harm than providing useful information. >> > >> >> Acked-by: Andy Lutomirski <luto@kernel.org> >> >> Maybe add to changelog: >> >> Switch from memmove() to memcpy() because memmove() can't be called >> from noinstr code. > > Yes please, because I was about to say that there was changes that > didn't seem to fit the change log. > > I would also add a comment in the code saying that we need the temp > variable to use memcpy as memmove can't be used in noinstr code.
Looking at an updated version of the tree, I see the acked-by from Andy, but not comment about switching from memmove to memcpy.
Also, I notice a significant undocumented change in this patch: it changes a this_cpu_read() (which presumes preemption is enabled) to a __this_cpu_read().
So the 100$ question: is preemption enabled or not in fixup_bad_iret() ? And of course that change should be documented in the commit message.
Thanks,
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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