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 8613A8002A for ; Fri, 26 Apr 2024 04:01:33 +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=1714104093; cv=none; b=FvUeDjh4YxPaFEutQlzpDyT/hSfPblZoyFiN5pLA19pPgjnqECZ6T6BgffFnAL2FGsoEe/FLLVhn9gLBQe8Vpuoz/uqn73yQBg2O5e7pt61T6fRpF+d9QC9aQ9ejTBnmtA5SB6lVWcM0jBWNsXmE/A1eYP7Zx3e77rDyxYOhSRo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714104093; c=relaxed/simple; bh=4Lpbk4s7UMMNqzr7bRvMXqfAqitbUtC9eRocNR4wIeI=; h=Date:To:From:Subject:Message-Id; b=KxF4jWR9tIeflca7C95zPrQxH/WrCDrxl1NrbEoACZcbBj/TWU7KwfMjVkLrW5vnMYICjXG0wHP8M0fw/pA/Mu/aOzYUJz4lD79qVEvMWGekKZVJXsski+s7QFtlzyy06z3l8LXo0umrYjGtAH7OhYWpJA8gagey2n8dlqkGDXg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=lN6nDgaM; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="lN6nDgaM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5ABECC113CD; Fri, 26 Apr 2024 04:01:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1714104093; bh=4Lpbk4s7UMMNqzr7bRvMXqfAqitbUtC9eRocNR4wIeI=; h=Date:To:From:Subject:From; b=lN6nDgaM2z27zkgYzwYfV2YqyoG5Ysw1MAWSvyUsh02XF8MdGy7xObLac75jfn4Sz pd7Vj6OBTKCKH64RFGlzZW/Zc1Y/7nun6p3wc+uVcYN0CcJtMpdKpWpJRYJz/U8V9Y k2dugz76v8sII0HCuz2coEfdFSv8XMv+CM++ru0A= Date: Thu, 25 Apr 2024 21:01:32 -0700 To: mm-commits@vger.kernel.org,tglx@linutronix.de,peterz@infradead.org,npiggin@gmail.com,naveen.n.rao@linux.ibm.com,mpe@ellerman.id.au,mingo@redhat.com,luto@kernel.org,Liam.Howlett@oracle.com,kirill.shutemov@linux.intel.com,keescook@chromium.org,James.Bottomley@HansenPartnership.com,hpa@zytor.com,guoren@kernel.org,deller@gmx.de,debug@rivosinc.com,dave.hansen@linux.intel.com,dan.j.williams@intel.com,christophe.leroy@csgroup.eu,broonie@kernel.org,bp@alien8.de,ast@kernel.org,aneesh.kumar@kernel.org,rick.p.edgecombe@intel.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-take-placement-mappings-gap-into-account.patch removed from -mm tree Message-Id: <20240426040133.5ABECC113CD@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: take placement mappings gap into account has been removed from the -mm tree. Its filename was mm-take-placement-mappings-gap-into-account.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Rick Edgecombe Subject: mm: take placement mappings gap into account Date: Mon, 25 Mar 2024 19:16:53 -0700 When memory is being placed, mmap() will take care to respect the guard gaps of certain types of memory (VM_SHADOWSTACK, VM_GROWSUP and VM_GROWSDOWN). In order to ensure guard gaps between mappings, mmap() needs to consider two things: 1. That the new mapping isn't placed in an any existing mappings guard gaps. 2. That the new mapping isn't placed such that any existing mappings are not in *its* guard gaps. The longstanding behavior of mmap() is to ensure 1, but not take any care around 2. So for example, if there is a PAGE_SIZE free area, and a mmap() with a PAGE_SIZE size, and a type that has a guard gap is being placed, mmap() may place the shadow stack in the PAGE_SIZE free area. Then the mapping that is supposed to have a guard gap will not have a gap to the adjacent VMA. For MAP_GROWSDOWN/VM_GROWSDOWN and MAP_GROWSUP/VM_GROWSUP this has not been a problem in practice because applications place these kinds of mappings very early, when there is not many mappings to find a space between. But for shadow stacks, they may be placed throughout the lifetime of the application. Use the start_gap field to find a space that includes the guard gap for the new mapping. Take care to not interfere with the alignment. Link: https://lkml.kernel.org/r/20240326021656.202649-12-rick.p.edgecombe@intel.com Signed-off-by: Rick Edgecombe Reviewed-by: Christophe Leroy Cc: Alexei Starovoitov Cc: Andy Lutomirski Cc: Aneesh Kumar K.V Cc: Borislav Petkov (AMD) Cc: Dan Williams Cc: Dave Hansen Cc: Deepak Gupta Cc: Guo Ren Cc: Helge Deller Cc: H. Peter Anvin (Intel) Cc: Ingo Molnar Cc: "James E.J. Bottomley" Cc: Kees Cook Cc: Kirill A. Shutemov Cc: Liam R. Howlett Cc: Mark Brown Cc: Michael Ellerman Cc: Naveen N. Rao Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- include/linux/mm.h | 1 + mm/mmap.c | 12 +++++++++--- 2 files changed, 10 insertions(+), 3 deletions(-) --- a/include/linux/mm.h~mm-take-placement-mappings-gap-into-account +++ a/include/linux/mm.h @@ -3468,6 +3468,7 @@ struct vm_unmapped_area_info { unsigned long high_limit; unsigned long align_mask; unsigned long align_offset; + unsigned long start_gap; }; extern unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info); --- a/mm/mmap.c~mm-take-placement-mappings-gap-into-account +++ a/mm/mmap.c @@ -1579,7 +1579,7 @@ static unsigned long unmapped_area(struc VMA_ITERATOR(vmi, current->mm, 0); /* Adjust search length to account for worst case alignment overhead */ - length = info->length + info->align_mask; + length = info->length + info->align_mask + info->start_gap; if (length < info->length) return -ENOMEM; @@ -1591,7 +1591,13 @@ retry: if (vma_iter_area_lowest(&vmi, low_limit, high_limit, length)) return -ENOMEM; - gap = vma_iter_addr(&vmi); + /* + * Adjust for the gap first so it doesn't interfere with the + * later alignment. The first step is the minimum needed to + * fulill the start gap, the next steps is the minimum to align + * that. It is the minimum needed to fulill both. + */ + gap = vma_iter_addr(&vmi) + info->start_gap; gap += (info->align_offset - gap) & info->align_mask; tmp = vma_next(&vmi); if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */ @@ -1630,7 +1636,7 @@ static unsigned long unmapped_area_topdo VMA_ITERATOR(vmi, current->mm, 0); /* Adjust search length to account for worst case alignment overhead */ - length = info->length + info->align_mask; + length = info->length + info->align_mask + info->start_gap; if (length < info->length) return -ENOMEM; _ Patches currently in -mm which might be from rick.p.edgecombe@intel.com are