d1811067ee
[ Upstream commit 5baf8b037debf4ec60108ccfeccb8636d1dbad81 ] Currently MTE is permitted in two circumstances (desiring to use MTE having been specified by the VM_MTE flag) - where MAP_ANONYMOUS is specified, as checked by arch_calc_vm_flag_bits() and actualised by setting the VM_MTE_ALLOWED flag, or if the file backing the mapping is shmem, in which case we set VM_MTE_ALLOWED in shmem_mmap() when the mmap hook is activated in mmap_region(). The function that checks that, if VM_MTE is set, VM_MTE_ALLOWED is also set is the arm64 implementation of arch_validate_flags(). Unfortunately, we intend to refactor mmap_region() to perform this check earlier, meaning that in the case of a shmem backing we will not have invoked shmem_mmap() yet, causing the mapping to fail spuriously. It is inappropriate to set this architecture-specific flag in general mm code anyway, so a sensible resolution of this issue is to instead move the check somewhere else. We resolve this by setting VM_MTE_ALLOWED much earlier in do_mmap(), via the arch_calc_vm_flag_bits() call. This is an appropriate place to do this as we already check for the MAP_ANONYMOUS case here, and the shmem file case is simply a variant of the same idea - we permit RAM-backed memory. This requires a modification to the arch_calc_vm_flag_bits() signature to pass in a pointer to the struct file associated with the mapping, however this is not too egregious as this is only used by two architectures anyway - arm64 and parisc. So this patch performs this adjustment and removes the unnecessary assignment of VM_MTE_ALLOWED in shmem_mmap(). [akpm@linux-foundation.org: fix whitespace, per Catalin] Link: https://lkml.kernel.org/r/ec251b20ba1964fb64cf1607d2ad80c47f3873df.1730224667.git.lorenzo.stoakes@oracle.com Fixes: deb0f6562884 ("mm/mmap: undo ->mmap() when arch_validate_flags() fails") Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Reported-by: Jann Horn <jannh@google.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andreas Larsson <andreas@gaisler.com> Cc: David S. Miller <davem@davemloft.net> Cc: Helge Deller <deller@gmx.de> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mark Brown <broonie@kernel.org> Cc: Peter Xu <peterx@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
91 lines
2.6 KiB
C
Executable file
91 lines
2.6 KiB
C
Executable file
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_MMAN_H__
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#define __ASM_MMAN_H__
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/shmem_fs.h>
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#include <linux/types.h>
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#include <uapi/asm/mman.h>
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static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
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unsigned long pkey __always_unused)
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{
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unsigned long ret = 0;
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if (system_supports_bti() && (prot & PROT_BTI))
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ret |= VM_ARM64_BTI;
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if (system_supports_mte() && (prot & PROT_MTE))
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ret |= VM_MTE;
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return ret;
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}
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#define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
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static inline unsigned long arch_calc_vm_flag_bits(struct file *file,
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unsigned long flags)
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{
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/*
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* Only allow MTE on anonymous mappings as these are guaranteed to be
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* backed by tags-capable memory. The vm_flags may be overridden by a
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* filesystem supporting MTE (RAM-based).
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*/
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if (system_supports_mte() &&
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((flags & MAP_ANONYMOUS) || shmem_file(file)))
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return VM_MTE_ALLOWED;
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return 0;
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}
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#define arch_calc_vm_flag_bits(file, flags) arch_calc_vm_flag_bits(file, flags)
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static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags)
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{
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pteval_t prot = 0;
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if (vm_flags & VM_ARM64_BTI)
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prot |= PTE_GP;
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/*
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* There are two conditions required for returning a Normal Tagged
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* memory type: (1) the user requested it via PROT_MTE passed to
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* mmap() or mprotect() and (2) the corresponding vma supports MTE. We
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* register (1) as VM_MTE in the vma->vm_flags and (2) as
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* VM_MTE_ALLOWED. Note that the latter can only be set during the
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* mmap() call since mprotect() does not accept MAP_* flags.
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* Checking for VM_MTE only is sufficient since arch_validate_flags()
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* does not permit (VM_MTE & !VM_MTE_ALLOWED).
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*/
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if (vm_flags & VM_MTE)
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prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED);
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return __pgprot(prot);
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}
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#define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags)
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static inline bool arch_validate_prot(unsigned long prot,
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unsigned long addr __always_unused)
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{
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unsigned long supported = PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM;
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if (system_supports_bti())
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supported |= PROT_BTI;
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if (system_supports_mte())
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supported |= PROT_MTE;
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return (prot & ~supported) == 0;
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}
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#define arch_validate_prot(prot, addr) arch_validate_prot(prot, addr)
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static inline bool arch_validate_flags(unsigned long vm_flags)
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{
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if (!system_supports_mte())
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return true;
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/* only allow VM_MTE if VM_MTE_ALLOWED has been set previously */
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return !(vm_flags & VM_MTE) || (vm_flags & VM_MTE_ALLOWED);
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}
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#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags)
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#endif /* ! __ASM_MMAN_H__ */
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