* Linus Torvalds <[EMAIL PROTECTED]> wrote:
> > +static int kgdb_get_mem(char *addr, unsigned char *buf, int count)
> > {
> > + if ((unsigned long)addr < TASK_SIZE)
> > + return -EFAULT;
> >
> > + return probe_kernel_read(buf, addr, count);
> > }
>
> Ok, so this is a pretty function after all the cleanups, but I
> actually don't think that "if ((unsigned long)addr < TASK_SIZE)" is
> really even asked for.
>
> Why not let kgdb look at user memory? I'd argue that in a lot of
> cases, it might be quite nice to do, to see what user arguments in
> memory are etc etc (think things like futexes, where user memory
> contents really do matter).
>
> So I'd suggest getting rid of the whole "kgdb_{get|set}_mem()"
> functions, and just using "probe_kernel_{read|write}()" directly
> instead.
ok, on a second thought: kgdb_{get|set}_mem() is _only_ used to validate
and set the software breakpoint (int3). And i think kgdb correctly
restricts that to kernel-space addresses only - you can typo an address
down into user-space and overwrite user-space memory and not know what
hit you ... [you can still explicitly touch user-space memory, but that
has to be done intentionally]
So to reduce the confusion i've removed these functions and open-coded
the probe_kernel_*() functions into kgdb_validate_break_address() and
kgdb_arch_set_breakpoint().
all other places already use probe_kernel_{read|write}. (Now, there are
a few stray TASK_SIZE checks still, i'll double check them and convert
them to access_ok() checks.)
btw., based on your previous comment about alignment, i found another
function that used weird alignment checks, kgdb_hex2mem():
if (count == 2 && ((long)mem & 1) == 0)
err = probe_kernel_write(mem, tmp_raw, 2);
else if (count == 4 && ((long)mem & 3) == 0)
err = probe_kernel_write(mem, tmp_raw, 4);
else if (count == 8 && ((long)mem & 7) == 0)
err = probe_kernel_write(mem, tmp_raw, 8);
else
err = probe_kernel_write(mem, tmp_raw, count);
return err;
}
I just converted it to:
return probe_kernel_write(mem, tmp_raw, count);
which looks _a lot_ cleaner.
Ingo
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