On Fri, Jul 24, 2020 at 11:27:46AM +0200, Ingo Molnar wrote:
>
> * Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote:
>
> > Use text_alloc() and text_free() instead of module_alloc() and
> > module_memfree() when an arch provides them.
> >
> > Cc: linux-mm@xxxxxxxxx
> > Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> > Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> > ---
> > kernel/kprobes.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> > index 4e46d96d4e16..611fcda9f6bf 100644
> > --- a/kernel/kprobes.c
> > +++ b/kernel/kprobes.c
> > @@ -40,6 +40,7 @@
> > #include <asm/cacheflush.h>
> > #include <asm/errno.h>
> > #include <linux/uaccess.h>
> > +#include <linux/vmalloc.h>
> >
> > #define KPROBE_HASH_BITS 6
> > #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
> > @@ -111,12 +112,20 @@ enum kprobe_slot_state {
> >
> > void __weak *alloc_insn_page(void)
> > {
> > +#ifdef CONFIG_ARCH_HAS_TEXT_ALLOC
> > + return text_alloc(PAGE_SIZE);
> > +#else
> > return module_alloc(PAGE_SIZE);
> > +#endif
> > }
> >
> > void __weak free_insn_page(void *page)
> > {
> > +#ifdef CONFIG_ARCH_HAS_TEXT_ALLOC
> > + text_free(page);
> > +#else
> > module_memfree(page);
> > +#endif
> > }
>
> I've read the observations in the other threads, but this #ifdef
> jungle is silly, it's a de-facto open coded text_alloc() with a
> module_alloc() fallback...
In the previous version I had:
https://lore.kernel.org/lkml/20200717030422.679972-4-jarkko.sakkinen@xxxxxxxxxxxxxxx/
and I had just calls to text_alloc() and text_free() in corresponding
snippet to the above.
I got this feedback from Mike:
https://lore.kernel.org/lkml/20200718162359.GA2919062@xxxxxxxxxx/
I'm not still sure that I fully understand this feedback as I don't see
any inherent and obvious difference to the v4. In that version fallbacks
are to module_alloc() and module_memfree() and text_alloc() and
text_memfree() can be overridden by arch.
> Thanks,
>
> Ingo
/Jarkko
