From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from audible.transient.net (audible.transient.net [24.143.126.66]) by smtp.subspace.kernel.org (Postfix) with SMTP id 56CE72AD00 for ; Mon, 9 Sep 2024 07:28:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=24.143.126.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725866931; cv=none; b=QpxyQIADs5b2sizqwCt9ZwwLYVR4r5W8WYHXn6A6wofuTbaWlblHS7cO2OzapyPpo6zD3dsN0veaLuujM4dsUYUtNF0oevhY4+N6UNsuPvlBoPr0YdD8fxEe7ywG9ZBtkg5f12MyoXPUvWISkmoDF4ja30utcLQhna2Is6J8g4U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725866931; c=relaxed/simple; bh=iPIS2/A4UyMGxN239RnR5liQztzw/zwjjc9c9v2vi1I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DS/bbibxP7SvjATz2n/v0HdmnYhihvSfSseQxRAhyUYNQJoez22iKp+/4Jxxl0CQ0hdxI3bLxy+pIRazEh9KSePoaj6q7Q/OeQoAePg0+TvwJEXk0hO3vycoV9RP02XSc6eWoinlKtgSmijzL0n34RWeudJh0kf8Wv8CepxtJoE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=audible.transient.net; spf=none smtp.mailfrom=audible.transient.net; arc=none smtp.client-ip=24.143.126.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=audible.transient.net Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=audible.transient.net Received: (qmail 2206 invoked from network); 9 Sep 2024 07:28:47 -0000 Received: from cucamonga.audible.transient.net (192.168.2.5) by canarsie.audible.transient.net with QMQP; 9 Sep 2024 07:28:47 -0000 Received: (nullmailer pid 23244 invoked by uid 1000); Mon, 09 Sep 2024 07:28:46 -0000 Date: Mon, 9 Sep 2024 07:28:46 +0000 From: Jamie Heilman To: Thomas Gleixner Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, peterz@infradead.org, stable@vger.kernel.org Subject: Re: regression in 6.6.46; arch/x86/mm/pti.c Message-ID: Mail-Followup-To: Thomas Gleixner , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, peterz@infradead.org, stable@vger.kernel.org References: <87h6apcp9x.ffs@tglx> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87h6apcp9x.ffs@tglx> Thomas Gleixner wrote: > On Mon, Sep 09 2024 at 05:03, Jamie Heilman wrote: > > 3db03fb4995e ("x86/mm: Fix pti_clone_entry_text() for i386") which got > > landed in 6.6.46, has introduced two back to back warnings on boot on > > my 32bit system (found on 6.6.50): > > Right. > > > Reverting that commit removes the warnings (tested against 6.6.50). > > The follow-on commit of c48b5a4cf312 ("x86/mm: Fix PTI for i386 some > > more") doesn't apply cleanly to 6.6.50, but I did try out a build of > > 6.11-rc7 and that works fine too with no warnings on boot. > > See backport below. Yep, that tests out fine for me too. Thanks! > --- > From: Thomas Gleixner > Date: Tue Aug 6 20:48:43 2024 +0200 > Subject: [PATCH 6.6.y, 6.1.y, 5.10.y] x86/mm: Fix PTI for i386 some more > > commit c48b5a4cf3125adb679e28ef093f66ff81368d05 upstream. > > So it turns out that we have to do two passes of > pti_clone_entry_text(), once before initcalls, such that device and > late initcalls can use user-mode-helper / modprobe and once after > free_initmem() / mark_readonly(). > > Now obviously mark_readonly() can cause PMD splits, and > pti_clone_pgtable() doesn't like that much. > > Allow the late clone to split PMDs so that pagetables stay in sync. > > [peterz: Changelog and comments] > Reported-by: Guenter Roeck > Signed-off-by: Thomas Gleixner > Signed-off-by: Peter Zijlstra (Intel) > Signed-off-by: Thomas Gleixner > Tested-by: Guenter Roeck > Link: https://lkml.kernel.org/r/20240806184843.GX37996@noisy.programming.kicks-ass.net > --- > arch/x86/mm/pti.c | 45 +++++++++++++++++++++++++++++---------------- > 1 file changed, 29 insertions(+), 16 deletions(-) > > --- a/arch/x86/mm/pti.c > +++ b/arch/x86/mm/pti.c > @@ -241,7 +241,7 @@ static pmd_t *pti_user_pagetable_walk_pm > * > * Returns a pointer to a PTE on success, or NULL on failure. > */ > -static pte_t *pti_user_pagetable_walk_pte(unsigned long address) > +static pte_t *pti_user_pagetable_walk_pte(unsigned long address, bool late_text) > { > gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO); > pmd_t *pmd; > @@ -251,10 +251,15 @@ static pte_t *pti_user_pagetable_walk_pt > if (!pmd) > return NULL; > > - /* We can't do anything sensible if we hit a large mapping. */ > + /* Large PMD mapping found */ > if (pmd_large(*pmd)) { > - WARN_ON(1); > - return NULL; > + /* Clear the PMD if we hit a large mapping from the first round */ > + if (late_text) { > + set_pmd(pmd, __pmd(0)); > + } else { > + WARN_ON_ONCE(1); > + return NULL; > + } > } > > if (pmd_none(*pmd)) { > @@ -283,7 +288,7 @@ static void __init pti_setup_vsyscall(vo > if (!pte || WARN_ON(level != PG_LEVEL_4K) || pte_none(*pte)) > return; > > - target_pte = pti_user_pagetable_walk_pte(VSYSCALL_ADDR); > + target_pte = pti_user_pagetable_walk_pte(VSYSCALL_ADDR, false); > if (WARN_ON(!target_pte)) > return; > > @@ -301,7 +306,7 @@ enum pti_clone_level { > > static void > pti_clone_pgtable(unsigned long start, unsigned long end, > - enum pti_clone_level level) > + enum pti_clone_level level, bool late_text) > { > unsigned long addr; > > @@ -390,7 +395,7 @@ pti_clone_pgtable(unsigned long start, u > return; > > /* Allocate PTE in the user page-table */ > - target_pte = pti_user_pagetable_walk_pte(addr); > + target_pte = pti_user_pagetable_walk_pte(addr, late_text); > if (WARN_ON(!target_pte)) > return; > > @@ -453,7 +458,7 @@ static void __init pti_clone_user_shared > phys_addr_t pa = per_cpu_ptr_to_phys((void *)va); > pte_t *target_pte; > > - target_pte = pti_user_pagetable_walk_pte(va); > + target_pte = pti_user_pagetable_walk_pte(va, false); > if (WARN_ON(!target_pte)) > return; > > @@ -476,7 +481,7 @@ static void __init pti_clone_user_shared > start = CPU_ENTRY_AREA_BASE; > end = start + (PAGE_SIZE * CPU_ENTRY_AREA_PAGES); > > - pti_clone_pgtable(start, end, PTI_CLONE_PMD); > + pti_clone_pgtable(start, end, PTI_CLONE_PMD, false); > } > #endif /* CONFIG_X86_64 */ > > @@ -493,11 +498,11 @@ static void __init pti_setup_espfix64(vo > /* > * Clone the populated PMDs of the entry text and force it RO. > */ > -static void pti_clone_entry_text(void) > +static void pti_clone_entry_text(bool late) > { > pti_clone_pgtable((unsigned long) __entry_text_start, > (unsigned long) __entry_text_end, > - PTI_LEVEL_KERNEL_IMAGE); > + PTI_LEVEL_KERNEL_IMAGE, late); > } > > /* > @@ -572,7 +577,7 @@ static void pti_clone_kernel_text(void) > * pti_set_kernel_image_nonglobal() did to clear the > * global bit. > */ > - pti_clone_pgtable(start, end_clone, PTI_LEVEL_KERNEL_IMAGE); > + pti_clone_pgtable(start, end_clone, PTI_LEVEL_KERNEL_IMAGE, false); > > /* > * pti_clone_pgtable() will set the global bit in any PMDs > @@ -639,8 +644,15 @@ void __init pti_init(void) > > /* Undo all global bits from the init pagetables in head_64.S: */ > pti_set_kernel_image_nonglobal(); > + > /* Replace some of the global bits just for shared entry text: */ > - pti_clone_entry_text(); > + /* > + * This is very early in boot. Device and Late initcalls can do > + * modprobe before free_initmem() and mark_readonly(). This > + * pti_clone_entry_text() allows those user-mode-helpers to function, > + * but notably the text is still RW. > + */ > + pti_clone_entry_text(false); > pti_setup_espfix64(); > pti_setup_vsyscall(); > } > @@ -657,10 +669,11 @@ void pti_finalize(void) > if (!boot_cpu_has(X86_FEATURE_PTI)) > return; > /* > - * We need to clone everything (again) that maps parts of the > - * kernel image. > + * This is after free_initmem() (all initcalls are done) and we've done > + * mark_readonly(). Text is now NX which might've split some PMDs > + * relative to the early clone. > */ > - pti_clone_entry_text(); > + pti_clone_entry_text(true); > pti_clone_kernel_text(); > > debug_checkwx_user(); > -- Jamie Heilman http://audible.transient.net/~jamie/