On Wed, 2008-05-14 at 16:12 -0700, [EMAIL PROTECTED] wrote: > From: Carl Love <[EMAIL PROTECTED]> > > Fix the 64 bit user code backtrace which currently may hang the system. > > Signed-off-by: Carl Love <[EMAIL PROTECTED]> > Cc: Maynard Johnson <[EMAIL PROTECTED]> > Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Hi Carl,
I'm a bit confused by this change ..
> diff -puN
> arch/powerpc/oprofile/backtrace.c~powerpc-fix-for-oprofile-callgraph-for-power-64-bit-user-apps
> arch/powerpc/oprofile/backtrace.c
> ---
> a/arch/powerpc/oprofile/backtrace.c~powerpc-fix-for-oprofile-callgraph-for-power-64-bit-user-apps
> +++ a/arch/powerpc/oprofile/backtrace.c
> @@ -53,19 +53,40 @@ static unsigned int user_getsp32(unsigne
> #ifdef CONFIG_PPC64
> static unsigned long user_getsp64(unsigned long sp, int is_first)
> {
> - unsigned long stack_frame[3];
> + unsigned long stk_frm_lr;
> + unsigned long stk_frm_sp;
> + unsigned long size;
> +
> + /* Issue the __copy_from_user_inatomic() third argument currently
> + * only takes sizes 1, 2, 4 or 8 bytes. Don't read more then the
> + * first 48 bytes of the stack frame. That is all that is
> + * guaranteed to exist. Reading more may cause the system to hang.
__copy_from_user_inatomic() accepts any value for n, it just has a
special case for 1, 2, 4 and 8 - but it should still work for other
values.
The old code copied 24 bytes from sp, and the new code copies 8 bytes
from sp and 8 bytes from sp + 16 - so I don't see where the 48 bytes
comes in to it?
Also the comment is a little hard to parse, I think you mean "Issue:
the ..", but I read "Issue" as a verb in that sentence. And "Don't read
more then" should be "than".
cheers
--
Michael Ellerman
OzLabs, IBM Australia Development Lab
wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)
We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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