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Commit 340a510c authored by Jan Kara's avatar Jan Kara Committed by Greg Kroah-Hartman
Browse files

mm: Handle 0 flags in _calc_vm_trans() macro 




[ Upstream commit 592e254502041f953e84d091eae2c68cba04c10b ]

_calc_vm_trans() does not handle the situation when some of the passed
flags are 0 (which can happen if these VM flags do not make sense for
the architecture). Improve the _calc_vm_trans() macro to return 0 in
such situation. Since all passed flags are constant, this does not add
any runtime overhead.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5ae69f45

include/linux/mman.h

+2 −1
Original line number Diff line number Diff line
@@ -63,8 +63,9 @@ static inline int arch_validate_prot(unsigned long prot) 
 * ("bit1" and "bit2" must be single bits)

 */

#define _calc_vm_trans(x, bit1, bit2) \

  ((!(bit1) || !(bit2)) ? 0 : \

  ((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \

   : ((x) & (bit1)) / ((bit1) / (bit2)))

   : ((x) & (bit1)) / ((bit1) / (bit2))))



/*

 * Combine the mmap "prot" argument into "vm_flags" used internally.