Re: [PATCH v3 2/5] ARM: mm: fault: Enable interrupts before invoking __do_user_fault()

["Russell King (Oracle)" <linux@armlinux.org.uk>]

On Tue, Dec 02, 2025 at 03:18:16PM +0100, Sebastian Andrzej Siewior wrote:
> On 2025-11-10 15:55:52 [+0100], To linux-arm-kernel@lists.infradead.org wrote:
> |
> |   https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=9460/1
> |
> | Moved to Discarded.
> |
> | This makes the issues with the branch predictor hardening worse if this
> | patch is merged on its own - since this adds another path where
> | interrupts are enabled before calling harden_branch_predictor() in
> | __do_user_fault(). It would be sensible to move the interrupt enable
> | into __do_user_fault().
> |
> |    *** PLEASE DO NOT REPLY TO THIS MESSAGE ***
> 
> I thought that we apply both.
> In 9462/1 I am moving harden_branch_predictor() out of __do_user_fault()
> because do_page_fault() needs the hardening before the interrupts are
> enabled. Do mean something like

If I apply 9460/1 without 9462/1 first, then it makes the problems
with the branch predictor hardening worse. I'm not prepared to do that.

However, 9462/1 is tied up in the discussions that are ongoing, and I'm
not going to short-circuit the still-ongoing discussions that touch
this area by applying this patch - which would screw up everyone's
proposals to fix the various many problems that are being discovered in
the 32-bit ARM fault handling.

This means I can't apply 9462/1 nor 9460/1.

Since 9463/1 likely requires these, I can't apply that one either.

Sorry.

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