Messages in this thread | | | Subject | Re: [PATCH v2 00/19] Add generic vdso_base tracking | From | Christophe Leroy <> | Date | Tue, 24 Nov 2020 07:53:58 +0100 |
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Le 24/11/2020 à 01:29, Dmitry Safonov a écrit : > v2 Changes: > - Rename user_landing to vdso_base as it tracks vDSO VMA start address, > rather than the explicit address to land (Andy) > - Reword and don't use "new-execed" and "new-born" task (Andy) > - Fix failures reported by build robot > > Started from discussion [1], where was noted that currently a couple of > architectures support mremap() for vdso/sigpage, but not munmap(). > If an application maps something on the ex-place of vdso/sigpage, > later after processing signal it will land there (good luck!) > > Patches set is based on linux-next (next-20201123) and it depends on > changes in x86/cleanups (those reclaim TIF_IA32/TIF_X32) and also > on my changes in akpm (fixing several mremap() issues).
I have a series that cleans up VDSO init on powerpc and migrates powerpc to _install_special_mapping() (patch 10 of the series).
https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=204396&state=%2A&archive=both
I'm wondering how we should coordinate with your series for merging.
I guess your series will also imply removal of arch_unmap() ? see https://elixir.bootlin.com/linux/v5.10-rc4/source/arch/powerpc/include/asm/mmu_context.h#L262
> > Logically, the patches set divides on: > - patch 1: a cleanup for patches in x86/cleanups > - patches 2-11: cleanups for arch_setup_additional_pages() > - patches 12-13: x86 signal changes for unmapped vdso > - patches 14-19: provide generic vdso_base in mm_struct > > In the end, besides cleanups, it's now more predictable what happens for > applications with unmapped vdso on architectures those support .mremap() > for vdso/sigpage. > > I'm aware of only one user that unmaps vdso - Valgrind [2]. > (there possibly are more, but this one is "special", it unmaps vdso, but > not vvar, which confuses CRIU [Checkpoint Restore In Userspace], that's > why I'm aware of it) > > Patches as a .git branch: > https://github.com/0x7f454c46/linux/tree/setup_additional_pages-v2 > > v1 Link: > https://lore.kernel.org/lkml/20201108051730.2042693-1-dima@arista.com/ > > [1]: https://lore.kernel.org/linux-arch/CAJwJo6ZANqYkSHbQ+3b+Fi_VT80MtrzEV5yreQAWx-L8j8x2zA@mail.gmail.com/ > [2]: https://github.com/checkpoint-restore/criu/issues/488 >
Christophe
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