Messages in this thread Patch in this message | | | From | Will Deacon <> | Subject | [PATCH] nospec: Move array_index_nospec parameter checking into separate macro | Date | Mon, 5 Feb 2018 14:16:06 +0000 |
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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.
Cc: Dan Williams <dan.j.williams@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Will Deacon <will.deacon@arm.com> --- include/linux/nospec.h | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-)
diff --git a/include/linux/nospec.h b/include/linux/nospec.h index b99bced39ac2..fbc98e2c8228 100644 --- a/include/linux/nospec.h +++ b/include/linux/nospec.h @@ -20,20 +20,6 @@ static inline unsigned long array_index_mask_nospec(unsigned long index, 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 * thinks the mask is not needed. The compiler does not take * into account the value of @index under speculation. @@ -44,6 +30,26 @@ static inline unsigned long array_index_mask_nospec(unsigned long index, #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 * * For a code sequence like: @@ -61,7 +67,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index, ({ \ typeof(index) _i = (index); \ 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(_s) > sizeof(long)); \ -- 2.1.4
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