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nospec: Move array_index_nospec() parameter checking into separate macro 

For architectures providing their own implementation of
array_index_mask_nospec() in asm/barrier.h, attempting to use WARN_ONCE() to
complain about out-of-range parameters using WARN_ON() results in a mess
of mutually-dependent include files.

Rather than unpick the dependencies, simply have the core code in nospec.h
perform the checking for us.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1517840166-15399-1-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Will Deacon 2018-02-05 14:16:06 +00:00 committed by Ingo Molnar
parent be3233fbfc
commit 8fa80c503b
1 changed files with 21 additions and 15 deletions
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36
include/linux/nospec.h
View File

@ -19,20 +19,6 @@
static inline unsigned long array_index_mask_nospec(unsigned long index, static inline unsigned long array_index_mask_nospec(unsigned long index,
unsigned long size) unsigned long size)
{ {
/*
* Warn developers about inappropriate array_index_nospec() usage.
*
* Even if the CPU speculates past the WARN_ONCE branch, the
* sign bit of @index is taken into account when generating the
* mask.
*
* This warning is compiled out when the compiler can infer that
* @index and @size are less than LONG_MAX.
*/
if (WARN_ONCE(index > LONG_MAX || size > LONG_MAX,
"array_index_nospec() limited to range of [0, LONG_MAX]\n"))
return 0;
/* /*
* Always calculate and emit the mask even if the compiler * Always calculate and emit the mask even if the compiler
* thinks the mask is not needed. The compiler does not take * thinks the mask is not needed. The compiler does not take
@ -43,6 +29,26 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
} }
#endif #endif
/*
* Warn developers about inappropriate array_index_nospec() usage.
*
* Even if the CPU speculates past the WARN_ONCE branch, the
* sign bit of @index is taken into account when generating the
* mask.
*
* This warning is compiled out when the compiler can infer that
* @index and @size are less than LONG_MAX.
*/
#define array_index_mask_nospec_check(index, size) \
({ \
if (WARN_ONCE(index > LONG_MAX || size > LONG_MAX, \
"array_index_nospec() limited to range of [0, LONG_MAX]\n")) \
_mask = 0; \
else \
_mask = array_index_mask_nospec(index, size); \
_mask; \
})
/* /*
* array_index_nospec - sanitize an array index after a bounds check * array_index_nospec - sanitize an array index after a bounds check
* *
@ -61,7 +67,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
({ \ ({ \
typeof(index) _i = (index); \ typeof(index) _i = (index); \
typeof(size) _s = (size); \ typeof(size) _s = (size); \
unsigned long _mask = array_index_mask_nospec(_i, _s); \ unsigned long _mask = array_index_mask_nospec_check(_i, _s); \
\ \
BUILD_BUG_ON(sizeof(_i) > sizeof(long)); \ BUILD_BUG_ON(sizeof(_i) > sizeof(long)); \
BUILD_BUG_ON(sizeof(_s) > sizeof(long)); \ BUILD_BUG_ON(sizeof(_s) > sizeof(long)); \