Messages in this thread | | | Date | Tue, 18 Feb 2014 12:02:07 -0800 | Subject | Re: [PATCH 12/14] staging: binder: Fix ABI for 64bit Android | From | John Stultz <> |
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On Tue, Feb 18, 2014 at 11:49 AM, Greg KH <gregkh@linuxfoundation.org> wrote: > On Tue, Feb 18, 2014 at 11:30:26AM -0800, John Stultz wrote: >> On Tue, Feb 18, 2014 at 11:08 AM, Greg KH <gregkh@linuxfoundation.org> wrote: >> > On Mon, Feb 17, 2014 at 01:58:40PM -0800, John Stultz wrote: >> >> From: Serban Constantinescu <serban.constantinescu@arm.com> >> >> >> >> This patch fixes the ABI for 64bit Android userspace. >> >> BC_REQUEST_DEATH_NOTIFICATION and BC_CLEAR_DEATH_NOTIFICATION claim >> >> to be using struct binder_ptr_cookie, but they are using a 32bit handle >> >> and a pointer. >> >> >> >> On 32bit systems the payload size is the same as the size of struct >> >> binder_ptr_cookie, however for 64bit systems this will differ. This >> >> patch adds struct binder_handle_cookie that fixes this issue for 64bit >> >> Android. >> >> >> >> Since there are no 64bit users of this interface that we know of this >> >> change should not affect any existing systems. >> > >> > But you are changing the ioctl structures here, what is that going to >> > cause with old programs? >> >> So I'd be glad for Serban or Arve to clarify, but my understanding >> (and as is described in the commit message) is that the assumption is >> there are no 64bit binder users at this point, and the ioctl structure >> changes are made such that existing 32bit applications are unaffected. > > How does changing the structure size, and contents, not affect any > applications or the kernel code? What am I missing here?
On 32bit pointers and ints are the same size? (Years ago I sat through your presentation on this, so I'm worried I'm missing something here :)
struct binder_ptr_cookie { void *ptr; void *cookie; };
struct binder_handle_cookie { __u32 handle; void *cookie; } __attribute__((packed));
On 32bit systems these are the same size. Now on 64bit systems, this changes things, and would break users, but the assumption here is there are no pre-existing 64bit binder users.
>> >> Cc: Colin Cross <ccross@android.com> >> >> Cc: Arve Hjønnevåg <arve@android.com> >> >> Cc: Serban Constantinescu <serban.constantinescu@arm.com> >> >> Cc: Android Kernel Team <kernel-team@android.com> >> > >> > I am going to require Acks from someone on the Android team to accept >> > this, or any other 64bit binder patch, given all the back-and-forth that >> > has happened with the different patch sets here over the past year or >> > so. >> >> Certainly reasonable given the earlier back and forth. For extra >> context, these have been merged into the 3.10 AOSP by Arve: >> https://android-review.googlesource.com/#/c/79228/ > > That's good to see, and a good reason to get them merged, but better > descriptions and acks would be nice to have :) > > How about sending these as a separate series when all worked out, as > lots of people seem interested in them?
Yep. Will do.
thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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