[PATCH 1/4] ARM: kprobes: Fix probing of conditionally executed instructions

[Tixy]

On Mon, 2011-04-04 at 17:00 -0400, Nicolas Pitre wrote:
> On Mon, 4 Apr 2011, Tixy wrote:
> 
> > diff --git a/arch/arm/kernel/kprobes-decode.c b/arch/arm/kernel/kprobes-decode.c
> > index 8f6ed43..c88c8d2 100644
> > --- a/arch/arm/kernel/kprobes-decode.c
> > +++ b/arch/arm/kernel/kprobes-decode.c
> > @@ -63,6 +63,7 @@
> >  
> >  #include <linux/kernel.h>
> >  #include <linux/kprobes.h>
> > +#include "kprobes-decode.h"
> >  
> >  #define sign_extend(x, signbit) ((x) | (0 - ((x) & (1 << (signbit)))))
> >  
> > @@ -1384,6 +1385,13 @@ space_cccc_111x(kprobe_opcode_t insn, struct arch_specific_insn *asi)
> >  	return INSN_GOOD;
> >  }
> >  
> > +static kprobe_check_cc* const condition_checks[16] = {
> > +	&__check_eq, &__check_ne, &__check_cs, &__check_cc,
> > +	&__check_mi, &__check_pl, &__check_vs, &__check_vc,
> > +	&__check_hi, &__check_ls, &__check_ge, &__check_lt,
> > +	&__check_gt, &__check_le, &__check_al, &__check_al
> > +};
> 
> Here you create an array of function pointers.
> 
> > diff --git a/arch/arm/kernel/kprobes-decode.h b/arch/arm/kernel/kprobes-decode.h
> > new file mode 100644
> > index 0000000..d6b4337
> > --- /dev/null
> > +++ b/arch/arm/kernel/kprobes-decode.h
> > @@ -0,0 +1,98 @@
> > +/*
> > + * arch/arm/kernel/kprobes-decode.h
> > + *
> > + * Copyright (C) 2011 Jon Medhurst <tixy at yxit.co.uk>.
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +static inline unsigned long __kprobes __check_eq(unsigned long cpsr)
> > +{
> > +	return cpsr & PSR_Z_BIT;
> > +}
> 
> And those functions are declared static inline in a header file.
> 
> Because the array needs pointers to those functions, there is no way the 
> compiler will be able to make them inline.  Better put them right before 
> the array.

Those functions will also be needed in future for use in a switch
statement for thumb handling code. I wanted to avoid cut'n'paste of the
tests.

If you want, I can put them in the C file now, and move them to a header
when the thumb code gets released. I guess I should have done that
anyway, the thumb code could evolve.

I'm still getting use to juggling patches and branches now the ARM fixes
have interrupted the thumb work.

-- 
Tixy