Messages in this thread | | | Date | Tue, 19 Sep 2017 14:30:57 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH 1/3] kcov: remove #ifdef CONFIG_RANDOMIZE_BASE |
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Hi,
On Tue, Sep 19, 2017 at 03:46:46PM +0300, Andrey Ryabinin wrote: > There is no need to surround kaslr_offset() with CONFIG_RANDOMIZE_BASE ifdef. > kaslr_offset() will just return 0 if CONFIG_RANDOMIZE_BASE isn't set. > > Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> > --- > kernel/kcov.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/kernel/kcov.c b/kernel/kcov.c > index 3f693a0f6f3e..2f0e7a7c7afc 100644 > --- a/kernel/kcov.c > +++ b/kernel/kcov.c > @@ -69,9 +69,7 @@ void notrace __sanitizer_cov_trace_pc(void) > unsigned long pos; > unsigned long ip = _RET_IP_; > > -#ifdef CONFIG_RANDOMIZE_BASE > ip -= kaslr_offset(); > -#endif
I think this is sound, but as Dmitry points out it'll mean we do some pointless work. For example on arm64 we have:
static inline unsigned long kaslr_offset(void) { return kimage_vaddr - KIMAGE_VADDR; }
... where kimage_vaddr is a global variable, and KIMAGE_VADDR is a constant (and should be identical for !CONFIG_RANDOMIZE_BASE kernels).
I think it would be reasonable to make that:
static inline unsigned long kaslr_offset(void) { if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) return 0;
return kimage_vaddr - KIMAGE_VADDR; }
... and simplify callers as above.
Thanks, Mark.
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