On Fri, May 21, 2021 at 03:12:10PM -0700, Yu-cheng Yu wrote:

When newer VM flags are being created, such as VM_MTE, it becomes necessary
for mmap/mprotect to verify if certain flags are being applied to an
anonymous VMA.

To solve this, one approach is adding a VM flag to track that MAP_ANONYMOUS
is specified [1], and then using the flag in arch_validate_flags().

Another approach is passing the VMA to arch_validate_flags(), and check
vma_is_anonymous().

To prepare the introduction of PROT_SHADOW_STACK, which creates a shadow
stack mapping and can be applied only to an anonymous VMA, update
arch_validate_flags() to pass in the VMA.

[1] commit 9f3419315f3c ("arm64: mte: Add PROT_MTE support to mmap() and mprotect()"),

Signed-off-by: Yu-cheng Yu <redacted>
Reviewed-by: Kirill A. Shutemov <redacted>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <redacted>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>

For arm64:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>