[RFC v3 PATCH 0/7] Ksplice: Rebootless kernel updates

From: Jeff Arnold
Date: Fri Nov 21 2008 - 22:43:57 EST

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These patches add support for Ksplice [1], a rebootless update system, to
the kernel. We now think that Ksplice is ready to be merged (ideally into
-mm), and we are sending this RFC to see whether we can shake loose any
comments or code review. If people have concerns about Ksplice, we'd like
to hear them.

[1] http://www.ksplice.com/download

I previously mentioned Ksplice to the LKML in April [2], and I submitted
RFC patches to the LKML in September [3]. The basic idea is that Ksplice
can apply an update to a running Linux kernel based only on a source code
patch and the original kernel source. The Ksplice technical overview
document [4] describes the design of Ksplice and one of the ways that
Ksplice has been evaluated.

[2] http://lkml.org/lkml/2008/4/23/330
[3] http://lkml.org/lkml/2008/9/13/6
[4] http://www.ksplice.com/doc/ksplice.pdf

Specifically, Ksplice has been used to correct every significant Linux
kernel CVE from May 2005 to May 2008 [5]. 88% of these CVEs can be fixed
without writing any new code at all; the remaining 12% of CVEs require a
minimal amount of new code (on average, roughly 20 new
semicolon-terminated lines per CVE).

[5] http://www.ksplice.com/cve-evaluation

The interface between the Ksplice kernel component and the userspace
utilities is documented in the last patch of this series. The current
implementation of the userspace utilities is available from the Ksplice
website and the Ksplice git repository [6]. The Ksplice userspace
utilities transparently support both "integrated" operation (updating a
kernel patched with this patch series) and "standalone" operation
(updating a completely unmodified kernel).

[6] http://www.ksplice.com/git/ksplice.git

Just to let you know what direction we are going in: We're currently
working on the problem of making it feasible to apply the entire stable
tree using Ksplice. Although Ksplice's original evaluation focused on
patches for CVEs, we understand the idea that "security bugs are just
'normal bugs'" [7] (i.e., tracking security bugs separately from normal
bugs can be difficult and isn't necessarily advisable). We ultimately
want to provide to long-running machines hot updates for all of the bug
fixes that go into the corresponding stable tree. We think that
long-running machines will be more secure and reliable if they can
regularly be updated to the latest stable kernel code (along with the
usual user space updates provided by distributions).

[7] http://lkml.org/lkml/2008/7/14/465

Even though work on Ksplice is ongoing, I think that merging Ksplice makes
sense at this point because (1) development on the Ksplice kernel code has
stabilized, and (2) the system, as it currently stands, can be useful in a
variety of situations.

Jeff Arnold
jbarnold@xxxxxxx

Changes since v2:
- added taint flag, as requested by Alexey Dobriyan
- various speed optimizations
- support for replacing functions mapped read-only (CONFIG_DEBUG_RODATA)
- run-pre matching extended to bug table, ex_table, exported symbol table
- added hooks for calling custom code during the update process
- struct ksplice_export eliminated (struct ksplice_patch used instead)
- minor sysfs API changes
- added support for ksplice-apply's --partial option
- improved -ffunction-sections patches and added them to this patch series
- dropped ARM support for now, for simplicity

==

Documentation/ksplice.txt | 282 ++
Documentation/mutex-design.txt | 4 +-
MAINTAINERS | 10 +
Makefile | 4 +
arch/Kconfig | 14 +
arch/alpha/kernel/head.S | 2 +-
arch/alpha/kernel/init_task.c | 2 +-
arch/alpha/kernel/vmlinux.lds.S | 14 +-
arch/arm/kernel/head-nommu.S | 3 +-
arch/arm/kernel/head.S | 3 +-
arch/arm/kernel/init_task.c | 2 +-
arch/arm/kernel/vmlinux.lds.S | 14 +-
arch/arm/mm/proc-v6.S | 2 +-
arch/arm/mm/proc-v7.S | 2 +-
arch/arm/mm/tlb-v6.S | 2 +-
arch/arm/mm/tlb-v7.S | 2 +-
arch/avr32/kernel/init_task.c | 2 +-
arch/avr32/kernel/vmlinux.lds.S | 6 +-
arch/avr32/mm/init.c | 2 +-
arch/blackfin/kernel/vmlinux.lds.S | 2 +-
arch/cris/kernel/process.c | 2 +-
arch/frv/kernel/break.S | 4 +-
arch/frv/kernel/entry.S | 2 +-
arch/frv/kernel/head-mmu-fr451.S | 2 +-
arch/frv/kernel/head-uc-fr401.S | 2 +-
arch/frv/kernel/head-uc-fr451.S | 2 +-
arch/frv/kernel/head-uc-fr555.S | 2 +-
arch/frv/kernel/head.S | 4 +-
arch/frv/kernel/init_task.c | 2 +-
arch/frv/kernel/vmlinux.lds.S | 18 +-
arch/frv/mm/tlb-miss.S | 2 +-
arch/h8300/boot/compressed/head.S | 2 +-
arch/h8300/boot/compressed/vmlinux.lds | 2 +-
arch/h8300/kernel/init_task.c | 2 +-
arch/h8300/kernel/vmlinux.lds.S | 2 +-
arch/ia64/include/asm/asmmacro.h | 12 +-
arch/ia64/include/asm/cache.h | 2 +-
arch/ia64/include/asm/percpu.h | 2 +-
arch/ia64/kernel/Makefile | 2 +-
arch/ia64/kernel/gate-data.S | 2 +-
arch/ia64/kernel/gate.S | 8 +-
arch/ia64/kernel/gate.lds.S | 10 +-
arch/ia64/kernel/head.S | 2 +-
arch/ia64/kernel/init_task.c | 4 +-
arch/ia64/kernel/ivt.S | 2 +-
arch/ia64/kernel/minstate.h | 4 +-
arch/ia64/kernel/paravirtentry.S | 12 +-
arch/ia64/kernel/vmlinux.lds.S | 48 +-
arch/ia64/kvm/vmm_ivt.S | 2 +-
arch/ia64/xen/xensetup.S | 2 +-
arch/m32r/kernel/init_task.c | 2 +-
arch/m32r/kernel/vmlinux.lds.S | 6 +-
arch/m68k/kernel/head.S | 2 +-
arch/m68k/kernel/process.c | 2 +-
arch/m68k/kernel/sun3-head.S | 2 +-
arch/m68k/kernel/vmlinux-std.lds | 6 +-
arch/m68k/kernel/vmlinux-sun3.lds | 4 +-
arch/m68knommu/kernel/init_task.c | 2 +-
arch/m68knommu/kernel/vmlinux.lds.S | 6 +-
arch/m68knommu/platform/68360/head-ram.S | 2 +-
arch/m68knommu/platform/68360/head-rom.S | 2 +-
arch/mips/kernel/init_task.c | 2 +-
arch/mips/kernel/vmlinux.lds.S | 8 +-
arch/mips/lasat/image/head.S | 2 +-
arch/mips/lasat/image/romscript.normal | 2 +-
arch/mn10300/kernel/head.S | 2 +-
arch/mn10300/kernel/init_task.c | 2 +-
arch/mn10300/kernel/vmlinux.lds.S | 18 +-
arch/parisc/include/asm/cache.h | 2 +-
arch/parisc/include/asm/system.h | 2 +-
arch/parisc/kernel/head.S | 2 +-
arch/parisc/kernel/init_task.c | 8 +-
arch/parisc/kernel/vmlinux.lds.S | 26 +-
arch/powerpc/include/asm/cache.h | 2 +-
arch/powerpc/include/asm/page_64.h | 2 +-
arch/powerpc/include/asm/ppc_asm.h | 4 +-
arch/powerpc/kernel/head_32.S | 2 +-
arch/powerpc/kernel/head_40x.S | 2 +-
arch/powerpc/kernel/head_44x.S | 2 +-
arch/powerpc/kernel/head_8xx.S | 2 +-
arch/powerpc/kernel/head_fsl_booke.S | 2 +-
arch/powerpc/kernel/init_task.c | 2 +-
arch/powerpc/kernel/machine_kexec_64.c | 2 +-
arch/powerpc/kernel/vdso.c | 2 +-
arch/powerpc/kernel/vdso32/vdso32_wrapper.S | 2 +-
arch/powerpc/kernel/vdso64/vdso64_wrapper.S | 2 +-
arch/powerpc/kernel/vmlinux.lds.S | 28 +-
arch/s390/include/asm/cache.h | 2 +-
arch/s390/kernel/head.S | 2 +-
arch/s390/kernel/init_task.c | 2 +-
arch/s390/kernel/vmlinux.lds.S | 20 +-
arch/sh/include/asm/cache.h | 2 +-
arch/sh/kernel/cpu/sh5/entry.S | 4 +-
arch/sh/kernel/head_32.S | 2 +-
arch/sh/kernel/head_64.S | 2 +-
arch/sh/kernel/init_task.c | 2 +-
arch/sh/kernel/irq.c | 4 +-
arch/sh/kernel/vmlinux_32.lds.S | 14 +-
arch/sh/kernel/vmlinux_64.lds.S | 14 +-
arch/sparc/boot/btfixupprep.c | 4 +-
arch/sparc/include/asm/cache.h | 2 +-
arch/sparc/kernel/head.S | 2 +-
arch/sparc/kernel/vmlinux.lds.S | 8 +-
arch/sparc64/kernel/head.S | 2 +-
arch/sparc64/kernel/vmlinux.lds.S | 8 +-
arch/um/include/asm/common.lds.S | 4 +-
arch/um/kernel/dyn.lds.S | 4 +-
arch/um/kernel/init_task.c | 4 +-
arch/um/kernel/uml.lds.S | 4 +-
arch/x86/Kconfig | 1 +
arch/x86/boot/compressed/head_32.S | 2 +-
arch/x86/boot/compressed/head_64.S | 2 +-
arch/x86/boot/compressed/vmlinux.scr | 2 +-
arch/x86/boot/compressed/vmlinux_32.lds | 14 +-
arch/x86/boot/compressed/vmlinux_64.lds | 10 +-
arch/x86/include/asm/cache.h | 4 +-
arch/x86/kernel/acpi/wakeup_32.S | 2 +-
arch/x86/kernel/head_32.S | 6 +-
arch/x86/kernel/head_64.S | 4 +-
arch/x86/kernel/init_task.c | 6 +-
arch/x86/kernel/ksplice-arch.c | 125 +
arch/x86/kernel/traps.c | 2 +-
arch/x86/kernel/vmlinux_32.lds.S | 37 +-
arch/x86/kernel/vmlinux_64.lds.S | 27 +-
arch/xtensa/kernel/head.S | 2 +-
arch/xtensa/kernel/init_task.c | 2 +-
arch/xtensa/kernel/vmlinux.lds.S | 6 +-
include/asm-frv/init.h | 8 +-
include/asm-generic/vmlinux.lds.h | 16 +-
include/linux/cache.h | 2 +-
include/linux/init.h | 8 +-
include/linux/kallsyms.h | 13 +
include/linux/kernel.h | 1 +
include/linux/ksplice.h | 212 ++
include/linux/linkage.h | 4 +-
include/linux/module.h | 42 +
include/linux/percpu.h | 12 +-
include/linux/spinlock.h | 2 +-
kernel/Makefile | 3 +
kernel/extable.c | 3 +
kernel/kallsyms.c | 19 +
kernel/ksplice.c | 2716 +++++++++++++++++
kernel/module.c | 164 +-
kernel/panic.c | 1 +
kernel/sched.c | 1 +
lib/Kconfig.debug | 9 +
lib/bug.c | 1 +
scripts/Makefile.modpost | 1 +
scripts/mod/modpost.c | 22 +-
scripts/recordmcount.pl | 6 +-
150 files changed, 3929 insertions(+), 409 deletions(-)
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Next message: Jeff Arnold: "[RFC v3 PATCH 1/7] Make section names compatible with -ffunction-sections -fdata-sections"
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