On Thu, Oct 31, 2013 at 01:38:57PM -0500, Tom wrote:
> From: Tom Musta <tommu...@gmail.com>
>
> This patch modifies the unaligned access routines of the sstep.c
> module so that it properly reverses the bytes of storage operands
> in the little endian kernel kernel.
This has rather a lot of #ifdefs inside function definitions, and for
little-endian it does the unaligned accesses one byte at a time. You
could avoid all the #ifdefs if you define the combining function in an
endian-dependant way and make read_mem_unaligned look something like
this:
#ifdef __LITTLE_ENDIAN__
#define combine_pieces(x, b, c, nd) ((x) + ((b) << (8 * (nd))))
#else
#define combine_pieces(x, b, c, nd) (((x) << (8 * (c))) + (b))
#endif
static int __kprobes read_mem_unaligned(unsigned long *dest, unsigned long ea,
int nb, struct pt_regs *regs)
{
int err;
int nd;
unsigned long x, b, c;
/* unaligned, do this in pieces */
x = 0;
for (nd = 0; nd < nb; nd += c) {
c = max_align(ea);
if (c > nb - nd)
c = max_align(nb - nd);
err = read_mem_aligned(&b, ea, c);
if (err)
return err;
x = combine_pieces(x, b, c, nd);
ea += c;
}
*dest = x;
return 0;
}
and do something analogous for write_mem_unaligned().
Paul.
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