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linux/arch/parisc
Lorenzo Stoakes 5baf8b037d mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling
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: deb0f65628 ("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>
2024-11-05 16:49:55 -08:00
..
boot move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
configs drm/display: Make DisplayPort CEC-over-AUX Kconfig name consistent 2024-03-28 11:26:47 +01:00
include mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling 2024-11-05 16:49:55 -08:00
kernel move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
lib parisc: add u16 support to cmpxchg() 2024-04-09 22:06:00 -07:00
math-emu parisc/math-emu: Remove unused struct 'exc_reg' 2024-05-10 15:09:15 +02:00
mm ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
net parisc: fix unaligned accesses in BPF 2024-07-29 16:19:07 +02:00
video arch: Rename fbdev header and source files 2024-05-03 17:07:50 +02:00
defpalo.conf
install.sh kbuild: Abort make on install failures 2024-07-20 13:34:54 +09:00
Kbuild
Kconfig dma-mapping updates for linux 6.12 2024-09-19 11:12:49 +02:00
Kconfig.debug
Makefile arch: Select fbdev helpers with CONFIG_VIDEO 2024-05-03 17:07:50 +02:00