linux-toradex.git/arch/um/kernel/tlb.c, branch v6.7

um: Declare fix_range_common as a static function

2023-02-01T21:11:29+00:00

It is only used within the same file.

Signed-off-by: Benjamin Berg 
Signed-off-by: Richard Weinberger

um: protect VMA iteration

2023-02-01T21:11:27+00:00

Due to changes in the iteration, there are now lockdep
checks indicating that we're missing locking here. Add
the missing locking where it's needed.

Signed-off-by: Johannes Berg 
Acked-By: Anton Ivanov 
Signed-off-by: Richard Weinberger

um: remove vma linked list walk

2022-09-27T02:46:20+00:00

Use the VMA iterator instead.

Link: https://lkml.kernel.org/r/20220906194824.2110408-40-Liam.Howlett@oracle.com
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Liam R. Howlett 
Reviewed-by: Davidlohr Bueso 
Tested-by: Yu Zhao 
Cc: Catalin Marinas 
Cc: David Hildenbrand 
Cc: David Howells 
Cc: SeongJae Park 
Cc: Sven Schnelle 
Cc: Vlastimil Babka 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

um: remove process stub VMA

2021-02-12T20:37:38+00:00

This mostly reverts the old commit 3963333fe676 ("uml: cover stubs
with a VMA") which had added a VMA to the existing PTEs. However,
there's no real reason to have the PTEs in the first place and the
VMA cannot be 'fixed' in place, which leads to bugs that userspace
could try to unmap them and be forcefully killed, or such. Also,
there's a bit of an ugly hole in userspace's address space.

Simplify all this: just install the stub code/page at the top of
the (inner) address space, i.e. put it just above TASK_SIZE. The
pages are simply hard-coded to be mapped in the userspace process
we use to implement an mm context, and they're out of reach of the
inner mmap/munmap/mprotect etc. since they're above TASK_SIZE.

Getting rid of the VMA also makes vma_merge() no longer hit one of
the VM_WARN_ON()s there because we installed a VMA while the code
assumes the stack VMA is the first one.

It also removes a lockdep warning about mmap_sem usage since we no
longer have uml_setup_stubs() and thus no longer need to do any
manipulation that would require mmap_sem in activate_mm().

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

um: defer killing userspace on page table update failures

2021-02-12T20:32:04+00:00

In some cases we can get to fix_range_common() with mmap_sem held,
and in others we get there without it being held. For example, we
get there with it held from sys_mprotect(), and without it held
from fork_handler().

Avoid any issues in this and simply defer killing the task until
it runs the next time. Do it on the mm so that another task that
shares the same mm can't continue running afterwards.

Cc: stable@vger.kernel.org
Fixes: 468f65976a8d ("um: Fix hung task in fix_range_common()")
Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

um: mm: check more comprehensively for stub changes

2021-02-12T20:31:08+00:00

If userspace tries to change the stub, we need to kill it,
because otherwise it can escape the virtual machine. In a
few cases the stub checks weren't good, e.g. if userspace
just tries to

	mmap(0x100000 - 0x1000, 0x3000, ...)

it could succeed to get a new private/anonymous mapping
replacing the stubs. Fix this by checking everywhere, and
checking for _overlap_, not just direct changes.

Cc: stable@vger.kernel.org
Fixes: 3963333fe676 ("uml: cover stubs with a VMA")
Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

Revert "um: support some of ARCH_HAS_SET_MEMORY"

2021-01-26T21:11:38+00:00

This reverts commit 963285b0b47a ("um: support some of
ARCH_HAS_SET_MEMORY"), as it turns out that it's not only not
working (due to um never using the protection bits in the
page tables) but also corrupts the page tables if used on a
non-vmalloc page, since um never allocates proper page tables
for the 'physmem' in the first place.

Fixing all this will take more effort, so for now revert it.

Reported-by: Benjamin Berg 
Fixes: 963285b0b47a ("um: support some of ARCH_HAS_SET_MEMORY")
Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

um: support some of ARCH_HAS_SET_MEMORY

2020-12-13T21:38:06+00:00

For now, only support set_memory_ro()/rw() which we need for
the stack protection in the next patch.

Signed-off-by: Johannes Berg 
Signed-off-by: Richard Weinberger

mmap locking API: convert mmap_sem comments

2020-06-09T16:39:14+00:00

Convert comments that reference mmap_sem to reference mmap_lock instead.

[akpm@linux-foundation.org: fix up linux-next leftovers]
[akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil]
[akpm@linux-foundation.org: more linux-next fixups, per Michel]

Signed-off-by: Michel Lespinasse 
Signed-off-by: Andrew Morton 
Reviewed-by: Vlastimil Babka 
Reviewed-by: Daniel Jordan 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Hugh Dickins 
Cc: Jason Gunthorpe 
Cc: Jerome Glisse 
Cc: John Hubbard 
Cc: Laurent Dufour 
Cc: Liam Howlett 
Cc: Matthew Wilcox 
Cc: Peter Zijlstra 
Cc: Ying Han 
Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com
Signed-off-by: Linus Torvalds

mmap locking API: use coccinelle to convert mmap_sem rwsem call sites

2020-06-09T16:39:14+00:00

This change converts the existing mmap_sem rwsem calls to use the new mmap
locking API instead.

The change is generated using coccinelle with the following rule:

// spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir .

@@
expression mm;
@@
(
-init_rwsem
+mmap_init_lock
|
-down_write
+mmap_write_lock
|
-down_write_killable
+mmap_write_lock_killable
|
-down_write_trylock
+mmap_write_trylock
|
-up_write
+mmap_write_unlock
|
-downgrade_write
+mmap_write_downgrade
|
-down_read
+mmap_read_lock
|
-down_read_killable
+mmap_read_lock_killable
|
-down_read_trylock
+mmap_read_trylock
|
-up_read
+mmap_read_unlock
)
-(&mm->mmap_sem)
+(mm)

Signed-off-by: Michel Lespinasse 
Signed-off-by: Andrew Morton 
Reviewed-by: Daniel Jordan 
Reviewed-by: Laurent Dufour 
Reviewed-by: Vlastimil Babka 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Hugh Dickins 
Cc: Jason Gunthorpe 
Cc: Jerome Glisse 
Cc: John Hubbard 
Cc: Liam Howlett 
Cc: Matthew Wilcox 
Cc: Peter Zijlstra 
Cc: Ying Han 
Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com
Signed-off-by: Linus Torvalds