| Message ID | alpine.LFD.2.00.1104271810450.24613@xanadu.home |
|---|---|
| State | New |
| Headers | show |
* Nicolas Pitre <nicolas.pitre@linaro.org> [110428 01:12]: > On Wed, 27 Apr 2011, Tony Lindgren wrote: > > > * Tony Lindgren <tony@atomide.com> [110427 05:44]: > > > We can't overwrite the running code when relocating only a small amount, > > > say 0x100 or so. > > > > > > There's no need to relocate all the way past the compressed kernel, > > > we just need to relocate past the size of the code in head.o. > > > > > > Updated patch below using the GOT end instead of the compressed > > > image end. > > > > Oops, the mov should be movle of course. Updated patch below. > > This is wrong. You're using r12 before it is fixed up with the > proper offset. Hmm I see. I guess I was thinking it only needs to be fixed up after the relocation. > And this could simply be fixed with a big enough constant like this: > > diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S > index 8dab5e3..71fc1d9 100644 > --- a/arch/arm/boot/compressed/head.S > +++ b/arch/arm/boot/compressed/head.S > @@ -250,8 +250,11 @@ restart: adr r0, LC0 > * Because we always copy ahead, we need to do it from the end and go > * backward in case the source and destination overlap. > */ > - /* Round up to next 256-byte boundary. */ > - add r10, r10, #256 > + /* > + * Round to a 256-byte boundary on the next page. This > + * avoids overwriting ourself if the offset is small. > + */ > + add r10, r10, #4096 > bic r10, r10, #255 > > sub r9, r6, r5 @ size to copy Yeah that's what I had originally, but then we'll be potentially hitting the same bug again once more cache flushing code etc gets added. Regards, Tony
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index 8dab5e3..71fc1d9 100644 --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -250,8 +250,11 @@ restart: adr r0, LC0 * Because we always copy ahead, we need to do it from the end and go * backward in case the source and destination overlap. */ - /* Round up to next 256-byte boundary. */ - add r10, r10, #256 + /* + * Round to a 256-byte boundary on the next page. This + * avoids overwriting ourself if the offset is small. + */ + add r10, r10, #4096 bic r10, r10, #255 sub r9, r6, r5 @ size to copy