From: Alexander Lobakin <[email protected]> Date: Tue, 7 Nov 2023 17:44:00 +0100
> From: Alexander Potapenko <[email protected]> > Date: Tue, 7 Nov 2023 17:33:56 +0100 > >> On Tue, Nov 7, 2023 at 2:23 PM Alexander Lobakin >> <[email protected]> wrote: [...] > I tested it on GCC 9 using modified make.cross from lkp and it triggers > on one more file: > > drivers/thermal/intel/intel_soc_dts_iosf.c: In function 'sys_get_curr_temp': > ./include/linux/bitmap.h:601:18: error: array subscript [1, > 288230376151711744] is outside array bounds of 'long unsigned int[1]' > [-Werror=array-bounds] > >> to give the compiler some hints about the range of values passed to >> bitmap_write() rather than suppressing the optimizations. > > OPTIMIZER_HIDE_VAR() doesn't disable optimizations if I get it > correctly, rather shuts up the compiler in cases like this one. > > I've been thinking of using __member_size() from fortify-string.h, we > could probably optimize the object code even a bit more while silencing > this warning. > Adding Kees, maybe he'd like to participate in sorting this out as well. This one seems to work. At least previously mad GCC 9.3.0 now sits quietly, as if I added OPTIMIZER_HIDE_VAR() as Yury suggested. Note that ideally @map should be marked as `POS` in both cases to help Clang, but `POS` gets undefined at the end of fortify-string.h, so I decided to not do that within this draft. Thanks, Olek --- diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index e8031a157db5..efa0a0287d7c 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -589,12 +589,14 @@ static inline unsigned long bitmap_read(const unsigned long *map, size_t index = BIT_WORD(start); unsigned long offset = start % BITS_PER_LONG; unsigned long space = BITS_PER_LONG - offset; + const size_t map_size = __member_size(map); unsigned long value_low, value_high; if (unlikely(!nbits || nbits > BITS_PER_LONG)) return 0; - if (space >= nbits) + if ((__builtin_constant_p(map_size) && map_size != SIZE_MAX && + index + 1 >= map_size / sizeof(long)) || space >= nbits) return (map[index] >> offset) & BITMAP_LAST_WORD_MASK(nbits); value_low = map[index] & BITMAP_FIRST_WORD_MASK(start); @@ -620,6 +622,7 @@ static inline unsigned long bitmap_read(const unsigned long *map, static inline void bitmap_write(unsigned long *map, unsigned long value, unsigned long start, unsigned long nbits) { + const size_t map_size = __member_size(map); size_t index; unsigned long offset; unsigned long space; @@ -638,7 +641,9 @@ static inline void bitmap_write(unsigned long *map, unsigned long value, map[index] &= (fit ? (~(mask << offset)) : ~BITMAP_FIRST_WORD_MASK(start)); map[index] |= value << offset; - if (fit) + + if ((__builtin_constant_p(map_size) && map_size != SIZE_MAX && + index + 1 >= map_size / sizeof(long)) || fit) return; map[index + 1] &= BITMAP_FIRST_WORD_MASK(start + nbits);
