From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 973A21F5820; Mon, 23 Jun 2025 21:43:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750714987; cv=none; b=QtLMJoXHJNNMOO3SIaSeXi+/MgO6wGhoVedcw7y9hAl/vapgHdEVHIERL4Er9TrRoBxvWkXFEZd3uIOXJ73HHGwWZxmrXI2PMjyr0eHLBDw5qrs2HbVwo+66pIpcMjrcEtOCGBDQIbRCyTUGuLZ468IdCR2ayv7tCNxmYFOnBnY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750714987; c=relaxed/simple; bh=Tgon6siZGWaxaYn3WDxTR+ligFlVIZWCQDWxb13zMck=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=W+tTeBnOtRHPbZNWN9bM3Fa5trKo9MYMw1jUt36oo9HG7pZ+6hh3ExkBoerTDQozk02D5VVQ9b8lryYg/cPm76gHM6ffLNaGv59NPW8K6jbLCQVbwkdKgpN/L/OUDD9W8LgfAp9NvUNzY+c7637uPD1ce0Ju4VPubWGnzUXki4s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sk2V+p30; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sk2V+p30" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27732C4CEEA; Mon, 23 Jun 2025 21:43:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1750714987; bh=Tgon6siZGWaxaYn3WDxTR+ligFlVIZWCQDWxb13zMck=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sk2V+p30hWQvE//PVcMWoadSF43HAxfSW2NY/IT+xGlLi0DVJN/PbmDMHQIwUmyq6 pmretY88MxzkrhRvlSZhtc85GOszYbyxIBH7pH2xsrezrR6K50INDwxRWedl2NcrHp RMfT2fiXgSSS8jh+bT1RRc60gw9etd0Wycd+X9hY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Simon Schuster , Andreas Oetken , Dinh Nguyen , Sasha Levin Subject: [PATCH 5.10 245/355] nios2: force update_mmu_cache on spurious tlb-permission--related pagefaults Date: Mon, 23 Jun 2025 15:07:26 +0200 Message-ID: <20250623130634.112329816@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250623130626.716971725@linuxfoundation.org> References: <20250623130626.716971725@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Simon Schuster [ Upstream commit 2d8a3179ea035f9341b6a73e5ba4029fc67e983d ] NIOS2 uses a software-managed TLB for virtual address translation. To flush a cache line, the original mapping is replaced by one to physical address 0x0 with no permissions (rwx mapped to 0) set. This can lead to TLB-permission--related traps when such a nominally flushed entry is encountered as a mapping for an otherwise valid virtual address within a process (e.g. due to an MMU-PID-namespace rollover that previously flushed the complete TLB including entries of existing, running processes). The default ptep_set_access_flags implementation from mm/pgtable-generic.c only forces a TLB-update when the page-table entry has changed within the page table: /* * [...] We return whether the PTE actually changed, which in turn * instructs the caller to do things like update__mmu_cache. [...] */ int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address, pte_t *ptep, pte_t entry, int dirty) { int changed = !pte_same(*ptep, entry); if (changed) { set_pte_at(vma->vm_mm, address, ptep, entry); flush_tlb_fix_spurious_fault(vma, address); } return changed; } However, no cross-referencing with the TLB-state occurs, so the flushing-induced pseudo entries that are responsible for the pagefault in the first place are never pre-empted from TLB on this code path. This commit fixes this behaviour by always requesting a TLB-update in this part of the pagefault handling, fixing spurious page-faults on the way. The handling is a straightforward port of the logic from the MIPS architecture via an arch-specific ptep_set_access_flags function ported from arch/mips/include/asm/pgtable.h. Signed-off-by: Simon Schuster Signed-off-by: Andreas Oetken Signed-off-by: Dinh Nguyen Signed-off-by: Sasha Levin --- arch/nios2/include/asm/pgtable.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/nios2/include/asm/pgtable.h b/arch/nios2/include/asm/pgtable.h index 2600d76c310c4..966fef8249bbb 100644 --- a/arch/nios2/include/asm/pgtable.h +++ b/arch/nios2/include/asm/pgtable.h @@ -277,4 +277,20 @@ extern void __init mmu_init(void); extern void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *pte); +static inline int pte_same(pte_t pte_a, pte_t pte_b); + +#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS +static inline int ptep_set_access_flags(struct vm_area_struct *vma, + unsigned long address, pte_t *ptep, + pte_t entry, int dirty) +{ + if (!pte_same(*ptep, entry)) + set_ptes(vma->vm_mm, address, ptep, entry, 1); + /* + * update_mmu_cache will unconditionally execute, handling both + * the case that the PTE changed and the spurious fault case. + */ + return true; +} + #endif /* _ASM_NIOS2_PGTABLE_H */ -- 2.39.5