Messages in this thread | | | Subject | Re: [PATCH 0/6] x86: 32-bit compatible C/R on x86_64 | From | Dmitry Safonov <> | Date | Wed, 1 Jun 2016 16:15:14 +0300 |
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On 06/01/2016 04:11 PM, Dmitry Safonov wrote: > This patches set is an attempt to add checkpoint/restore > for 32-bit tasks in compatibility mode on x86_64 hosts. > > Restore in CRIU starts from one root restoring process, which > reads info for all threads being restored from images files. > This information is used further to to find out which processes > share some resources. Later shared resources are restored only > by one process and all other inherit them. > After that it calls clone() and new threads restore their > properties in parallel. Those threads inherit all parent's > mappings and fetch properties from those mappings > (and do clone themself, if they have children/subthreads). [1] > Then starts restorer blob's play, it's PIE binary, which > unmaps all unneeded for restoring VMAs, maps new VMAs and > finalize restoring with sigreturn syscall. [2] > > To restore of 32-bit task we need three things to do in running > x86_64 restorer blob: > a) set code selector to __USER32_CS (to run 32-bit code); > b) remap vdso blob from 64-bit to 32-bit > This is primary needed because restore may happen on a different > kernel, which has different vDSO image than we had on dump. > c) if 32-bit vDSO differ to dumped image, move it on free place > and add jump trampolines to that place. > d) switch TIF_IA32 flag, so kernel would know that it deals with > compatible 32-bit application. > > From all this: > a) setting CS may be done from userspace, no patches needed; > b) patches 1-3 add ability to map different vDSO blobs on x86 kernel; > c) for remapping/moving 32-bit vDSO blob patches have been send earlier > and seems to be accepted [3] > d) and for swapping TIF_IA32 flag discussion with Andy ended in conclusion > that it's better to remove this flag completely. > Patches 4-6 deletes usage of TIF_IA32 from ptrace, signal and coredump > code. This is rework/resend of RFC [4] > > [1] https://criu.org/Checkpoint/Restore#Restore > [2] https://criu.org/Restorer_context > [3] https://lkml.org/lkml/2016/5/17/243 > [4] https://lkml.org/lkml/2016/4/25/650 > > Dmitry Safonov (6): > x86/vdso: unmap vdso blob on vvar mapping failure > x86/vdso: introduce do_map_vdso() and vdso_type enum > x86/arch_prctl/vdso: add ARCH_MAP_VDSO_* > x86/coredump: use core regs, rather that TIF_IA32 flag > x86/ptrace: down with test_thread_flag(TIF_IA32) > x86/signal: add SA_{X32,IA32}_ABI sa_flags
Oh, forgot to mention: this patches set is based on [3], so kernel build bot may be not happy about applying them. Anyway, I hope for the next revisions, the base-patches will be applied to linux-next and build-bot will test them just fine.
> > arch/x86/entry/vdso/vma.c | 72 +++++++++++++++++++++----------------- > arch/x86/ia32/ia32_signal.c | 2 +- > arch/x86/include/asm/compat.h | 8 ++--- > arch/x86/include/asm/fpu/signal.h | 6 ++++ > arch/x86/include/asm/vdso.h | 4 +++ > arch/x86/include/uapi/asm/prctl.h | 6 ++++ > arch/x86/include/uapi/asm/signal.h | 6 +++- > arch/x86/kernel/process_64.c | 10 ++++++ > arch/x86/kernel/ptrace.c | 2 +- > arch/x86/kernel/signal.c | 19 +++++----- > arch/x86/kernel/signal_compat.c | 30 ++++++++++++++-- > fs/binfmt_elf.c | 18 +++++----- > kernel/signal.c | 5 +++ > 13 files changed, 129 insertions(+), 59 deletions(-) >
-- Regards, Dmitry Safonov
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