Messages in this thread | | | Date | Mon, 19 Feb 2018 11:54:53 +0000 | From | Will Deacon <> | Subject | Re: [PATCH] nospec: Move array_index_nospec parameter checking into separate macro |
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Hi Geert,
On Mon, Feb 19, 2018 at 12:47:08PM +0100, Geert Uytterhoeven wrote: > On Mon, Feb 5, 2018 at 3:16 PM, Will Deacon <will.deacon@arm.com> wrote: > > 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>
[...]
> > @@ -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)); \ > > This change is commit 8fa80c503b484ddc ("nospec: Move array_index_nospec() > parameter checking into separate macro") in v4.16-rc2, and triggers the > following warning with gcc-4.1.2: > > net/wireless/nl80211.c: In function ‘parse_txq_params’: > net/wireless/nl80211.c:2099: warning: comparison is always false > due to limited range of data type > > Reverting the commit gets rid of the warning.
This is all getting ripped out, so stay tuned. The check is bogus, generates crappy code and I did a poor job at macro-ising it. Apart from that, it's great.
https://git.kernel.org/tip/1d91c1d2c80cb70e2e553845e278b87a960c04da
Will
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