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 DC10F2D047 for ; Wed, 27 Mar 2024 20:11:33 +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=1711570293; cv=none; b=rV47h3iS/Gb2p8+Y1gDfurqsKaKkZ3ziOP0/85L68XN97+Fz4GFMRdpAPXdJgw1Ohg2rQJq5/IpaNLaeACKcfGAAjYP93mN0DmCB6yzoSX9rziM1niE6Mpd1LGsVhiPUarkF3xjoZ934s3MkQpZ5QIdBnLCyHmOQbuxRwNEUbLg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711570293; c=relaxed/simple; bh=Qcru4Ci9BRDqxb3xVYds9ppMZinyFNvk/VBlR9hQYsU=; h=Date:To:From:Subject:Message-Id; b=TpnsMwEEehX7EdtGmABoU2UNHi/ZFcYDjTKgaapuE/lp2uH7wDG9NgyTiCUMMUv3wFqH4+9MxlHWHqRz9/i/D/+kAdeZhKhhA42neXcY/t+vff/vrf5jUUTDFnRYS1e/w71sekX0/g3/q2TnR9hmkwc8qC3+8oYUNyMBj1gqB5Y= 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=czn6I9Ea; 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="czn6I9Ea" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A326C433F1; Wed, 27 Mar 2024 20:11:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1711570293; bh=Qcru4Ci9BRDqxb3xVYds9ppMZinyFNvk/VBlR9hQYsU=; h=Date:To:From:Subject:From; b=czn6I9EaY7jAeFxek3rqTcDqifWNrKWBcpS/csyyoWwSWRrGlNkoLzIy53n4zFh18 2IfxXbp4bbc5c2Q2Q9+LkDzFA+oQhGUQZnldasCvE4g2sIVDn7baDil2dWFR2njLsB 6CDT/XhD9ZB0cijDsYzPEUUI70OLlYbxzyWeb2Zw= Date: Wed, 27 Mar 2024 13:11:32 -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: + mm-introduce-arch_get_unmapped_area_vmflags.patch added to mm-unstable branch Message-Id: <20240327201133.4A326C433F1@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: introduce arch_get_unmapped_area_vmflags() has been added to the -mm mm-unstable branch. Its filename is mm-introduce-arch_get_unmapped_area_vmflags.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-arch_get_unmapped_area_vmflags.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: introduce arch_get_unmapped_area_vmflags() Date: Mon, 25 Mar 2024 19:16:45 -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. In order to take the start gap into account, the maple tree search needs to know the size of start gap the new mapping will need. The call chain from do_mmap() to the actual maple tree search looks like this: do_mmap(size, vm_flags, map_flags, ..) mm/mmap.c:get_unmapped_area(size, map_flags, ...) arch_get_unmapped_area(size, map_flags, ...) vm_unmapped_area(struct vm_unmapped_area_info) One option would be to add another MAP_ flag to mean a one page start gap (as is for shadow stack), but this consumes a flag unnecessarily. Another option could be to simply increase the size passed in do_mmap() by the start gap size, and adjust after the fact, but this will interfere with the alignment requirements passed in struct vm_unmapped_area_info, and unknown to mmap.c. Instead, introduce variants of arch_get_unmapped_area/_topdown() that take vm_flags. In future changes, these variants can be used in mmap.c:get_unmapped_area() to allow the vm_flags to be passed through to vm_unmapped_area(), while preserving the normal arch_get_unmapped_area/_topdown() for the existing callers. Link: https://lkml.kernel.org/r/20240326021656.202649-4-rick.p.edgecombe@intel.com Signed-off-by: Rick Edgecombe Cc: Alexei Starovoitov Cc: Andy Lutomirski Cc: Aneesh Kumar K.V Cc: Borislav Petkov (AMD) Cc: Christophe Leroy 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/sched/mm.h | 17 +++++++++++++++++ mm/mmap.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+) --- a/include/linux/sched/mm.h~mm-introduce-arch_get_unmapped_area_vmflags +++ a/include/linux/sched/mm.h @@ -192,6 +192,23 @@ unsigned long mm_get_unmapped_area(struc unsigned long pgoff, unsigned long flags); unsigned long +arch_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags, vm_flags_t vm_flags); +unsigned long +arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags, vm_flags_t); + +unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm, + struct file *filp, + unsigned long addr, + unsigned long len, + unsigned long pgoff, + unsigned long flags, + vm_flags_t vm_flags); + +unsigned long generic_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags); --- a/mm/mmap.c~mm-introduce-arch_get_unmapped_area_vmflags +++ a/mm/mmap.c @@ -1807,6 +1807,34 @@ arch_get_unmapped_area_topdown(struct fi } #endif +#ifndef HAVE_ARCH_UNMAPPED_AREA_VMFLAGS +unsigned long +arch_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags) +{ + return arch_get_unmapped_area(filp, addr, len, pgoff, flags); +} + +unsigned long +arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags, vm_flags_t vm_flags) +{ + return arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags); +} +#endif + +unsigned long mm_get_unmapped_area_vmflags(struct mm_struct *mm, struct file *filp, + unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags, + vm_flags_t vm_flags) +{ + if (test_bit(MMF_TOPDOWN, &mm->flags)) + return arch_get_unmapped_area_topdown_vmflags(filp, addr, len, pgoff, + flags, vm_flags); + return arch_get_unmapped_area_vmflags(filp, addr, len, pgoff, flags, vm_flags); +} + unsigned long get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) _ 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