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 33E261514E5 for ; Wed, 27 Mar 2024 20:11:49 +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=1711570310; cv=none; b=X9AtJUdelBIsxEKtzAZRjt8g/kqlLUHRRxGycRmq62RybCcAVi+gSGVcwVfiEGb6MrdEP0tPfEjxWjXPr3nFB0nbR8gFNgYdjTz85dz7J9iXA57dDpMmK9DOGvTQo2W3wF2vlUYrEw4e0qrEf3ZJfX6jwl5JKZrrS/S9QnkSkcA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711570310; c=relaxed/simple; bh=SoW1WFbBVK9vLMzczN4nj1CYKieGfH8e7BgJSIuHxcU=; h=Date:To:From:Subject:Message-Id; b=obdgWS01oORZ1IGaPBPTdrEU7aNKVlrJmIeoIKorSCXps/jP7D1k2BWqKaM98n63o5BxD2fDY2YVynqp54gJQAQwSulfkEMzEncByil97Eezw48lAlMx5MYt/P4g9TkHX5NaL9gAPv268FMNMkrAGvczdbnDtVLOK0jmAZ3/tDI= 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=af6GoIxe; 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="af6GoIxe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AEE06C433C7; Wed, 27 Mar 2024 20:11:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1711570309; bh=SoW1WFbBVK9vLMzczN4nj1CYKieGfH8e7BgJSIuHxcU=; h=Date:To:From:Subject:From; b=af6GoIxeG5NLjhTTu3jA5fLPVMW5AY0d4oX0h3ghWABOIOFmUAghRnEg1tARwevbF Zc2zUSEVW22P/6n/Ddj2WE+zxTKlpqMMWE3Xc/mOB1TVUx5KAxsh3z0fwrxx7J6N2E CI6OtePnus3Q1Z/oG9syxMoJpgdE/3qcNNEpS9g0= Date: Wed, 27 Mar 2024 13:11:49 -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: + mm-take-placement-mappings-gap-into-account.patch added to mm-unstable branch Message-Id: <20240327201149.AEE06C433C7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: take placement mappings gap into account has been added to the -mm mm-unstable branch. Its filename is mm-take-placement-mappings-gap-into-account.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-take-placement-mappings-gap-into-account.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ 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 @@ -3467,6 +3467,7 @@ 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 proc-refactor-pde_get_unmapped_area-as-prep.patch mm-switch-mm-get_unmapped_area-to-a-flag.patch mm-introduce-arch_get_unmapped_area_vmflags.patch mm-remove-export-for-get_unmapped_area.patch mm-use-get_unmapped_area_vmflags.patch thp-add-thp_get_unmapped_area_vmflags.patch csky-use-initializer-for-struct-vm_unmapped_area_info.patch parisc-use-initializer-for-struct-vm_unmapped_area_info.patch powerpc-use-initializer-for-struct-vm_unmapped_area_info.patch treewide-use-initializer-for-struct-vm_unmapped_area_info.patch mm-take-placement-mappings-gap-into-account.patch x86-mm-implement-have_arch_unmapped_area_vmflags.patch x86-mm-care-about-shadow-stack-guard-gap-during-placement.patch selftests-x86-add-placement-guard-gap-test-for-shstk.patch