linux-kernel - Re: [PATCH v2 00/10] x86/module: rework ROX cache to avoid writable copy

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Message-ID: <20250122095101.GK8385@noisy.programming.kicks-ass.net>
Date: Wed, 22 Jan 2025 10:51:01 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Mike Rapoport <rppt@...nel.org>
Cc: x86@...nel.org, Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Anton Ivanov <anton.ivanov@...bridgegreys.com>,
	Borislav Petkov <bp@...en8.de>,
	Brendan Higgins <brendan.higgins@...ux.dev>,
	Daniel Gomez <da.gomez@...sung.com>,
	Daniel Thompson <danielt@...nel.org>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	David Gow <davidgow@...gle.com>,
	Douglas Anderson <dianders@...omium.org>,
	Ingo Molnar <mingo@...hat.com>,
	Jason Wessel <jason.wessel@...driver.com>,
	Jiri Kosina <jikos@...nel.org>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	Johannes Berg <johannes@...solutions.net>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Miroslav Benes <mbenes@...e.cz>, "H. Peter Anvin" <hpa@...or.com>,
	Petr Mladek <pmladek@...e.com>, Petr Pavlu <petr.pavlu@...e.com>,
	Rae Moar <rmoar@...gle.com>, Richard Weinberger <richard@....at>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Shuah Khan <shuah@...nel.org>, Song Liu <song@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	kgdb-bugreport@...ts.sourceforge.net, kunit-dev@...glegroups.com,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
	linux-mm@...ck.org, linux-modules@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org, linux-um@...ts.infradead.org,
	live-patching@...r.kernel.org
Subject: Re: [PATCH v2 00/10] x86/module: rework ROX cache to avoid writable
 copy

On Tue, Jan 21, 2025 at 01:36:47PM +0100, Peter Zijlstra wrote:
> On Tue, Jan 21, 2025 at 11:57:29AM +0200, Mike Rapoport wrote:
> 
> > Kirill A. Shutemov (1):
> >   x86/mm/pat: restore large ROX pages after fragmentation
> 
> The duplication between pmd and pud collapse is a bit annoying, but so
> be it.
> 
> > Mike Rapoport (Microsoft) (9):
> >   x86/mm/pat: cpa-test: fix length for CPA_ARRAY test
> >   x86/mm/pat: drop duplicate variable in cpa_flush()
> >   execmem: don't remove ROX cache from the direct map
> >   execmem: add API for temporal remapping as RW and restoring ROX afterwards
> >   module: introduce MODULE_STATE_GONE
> >   module: switch to execmem API for remapping as RW and restoring ROX
> >   Revert "x86/module: prepare module loading for ROX allocations of text"
> >   module: drop unused module_writable_address()
> >   x86: re-enable EXECMEM_ROX support
> 
> All these look good on a first reading, let me go build and test the
> various options.

I've tested:

GCC:  ibt=off
      ibt=on
LLVM: ibt-off,cfi=off
      ibt=off,cfi=kcfi
      ibt=on,cfi=off
      ibt=on,cfi=kcfi
      ibt=on,cfi=fineibt

And all of them were able to load a module, so yay!

My plan is to merge these patches into tip/x86/mm once we have -rc1.