[PATCH v2 0/4] Ksplice: Rebootless kernel updates

From: Tim Abbott
Date: Tue Feb 24 2009 - 19:27:02 EST

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This is an updated version of the Ksplice patch series. It applies to
Linux 2.6.29-rc5 with Rusty Russell's patch series for the module
subsystem from February 7 [0].

[0] http://lkml.org/lkml/2009/2/7/53

This patch series differs from the previous version in a few notable
ways:

(1) The Ksplice changes to the module loader have been removed from
this patch series because versions of them are already in Rusty
Russell's tree.

(2) Some of the data structures were renamed in response to
suggestions from Rusty Russell on the previous version of the patch
series

(3) The patch changing the kernel's magic section names to support
-ffunction-sections fdata-sections patch was rewritten in a cleaner
way. I believe this new version of the patch eliminates the primary
downside associated with previous iterations of the patch (in
particular, the need to specify section flags for many sections).

A detailed changelog is available below.

==

These patches add support for Ksplice [1], a rebootless update system,
to the kernel.

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

Jeff Arnold first mentioned Ksplice to the LKML last April [2], and
submitted patches to the LKML last September [3], November [4], and
December [5]. 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 [6]
describes the design of Ksplice and some 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://lkml.org/lkml/2008/11/21/484
[5] http://lkml.org/lkml/2008/12/5/330
[6] 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 [7]. 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).

[7] 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 [8]. 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).

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

We think that merging Ksplice makes sense at this point because (1)
development on the Ksplice kernel code has stabilized and (2) the
system is useful as it currently stands.

-Tim Abbott

Changes between v1 and v2:
- rewrote the -ffunction-sections -fdata-sections patches in a cleaner way
- rebased on top of Rusty Russell's module.c patch series for 2.6.30.
- replaced starts_with with strstarts.
- replaced __module_data_address with __module_address.
- renamed some data structures, as requested by Rusty Russell
- renamed struct ksplice_pack to struct ksplice_mod_change.
- created new struct ksplice_code, containing the symbols, relocs,
and sections for an object file.
- renamed helper modules to old_code modules, and primary modules to
new_code modules.
- renamed ksplice_module_list to ksplice_modules.
- renamed ksplice_symbol->vals to candidate_vals
- created new struct ksplice_hooks to organize the Ksplice hooks.
- improved Ksplice's kobject variable names.
- merged apply_patches and reverse_patches.
- added check to prevent reversing an update that has been partially
cold-applied.
- added support for patching multi-page data structures.
- added more function-level documentation, as requested by Ted Ts'o
- bail out earlier (to give a better error message) when there are
multiple writers to an update's stage file.

Changes between RFC v3 and v1:
- removed use of init_mm, as requested by Christoph Hellwig

Changes between RFC v2 and RFC v3:
- 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

No changes between RFC v1 and RFC v2.

==

Jeff Arnold (1):
Ksplice: Support updating x86-32 and x86-64

Tim Abbott (2):
Make section names compatible with -ffunction-sections
-fdata-sections
Ksplice: Export symbols needed for Ksplice

Waseem Daher (1):
x86: Add an option to compile with -ffunction-sections
-fdata-sections

Documentation/ksplice.txt | 304 +++
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 | 2 +-
arch/arm/kernel/head.S | 2 +-
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/cris/kernel/vmlinux.lds.S | 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 | 2 +-
arch/ia64/kernel/vmlinux.lds.S | 48 +-
arch/ia64/kvm/vmm_ivt.S | 2 +-
arch/ia64/xen/xensetup.S | 2 +-
arch/m32r/kernel/head.S | 2 +-
arch/m32r/kernel/init_task.c | 2 +-
arch/m32r/kernel/vmlinux.lds.S | 8 +-
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 | 16 +-
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/vdso.c | 2 +-
arch/s390/kernel/vdso32/vdso32_wrapper.S | 2 +-
arch/s390/kernel/vdso64/vdso64_wrapper.S | 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_32.S | 4 +-
arch/sparc/kernel/head_64.S | 2 +-
arch/sparc/kernel/init_task.c | 2 +-
arch/sparc/kernel/vmlinux.lds.S | 14 +-
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 | 2 +
arch/x86/boot/compressed/head_32.S | 2 +-
arch/x86/boot/compressed/head_64.S | 2 +-
arch/x86/boot/compressed/relocs.c | 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 | 4 +-
arch/x86/kernel/ksplice-arch.c | 96 +
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 | 19 +-
include/linux/cache.h | 2 +-
include/linux/init.h | 8 +-
include/linux/kernel.h | 1 +
include/linux/ksplice.h | 224 ++
include/linux/linkage.h | 4 +-
include/linux/percpu.h | 10 +-
include/linux/spinlock.h | 2 +-
kernel/Makefile | 3 +
kernel/extable.c | 3 +
kernel/ksplice.c | 2995 +++++++++++++++++++++++++++
kernel/module.c | 4 +-
kernel/panic.c | 1 +
kernel/sched.c | 1 +
lib/Kconfig.debug | 18 +
lib/bug.c | 1 +
scripts/Makefile.modpost | 1 +
scripts/mod/modpost.c | 22 +-
scripts/recordmcount.pl | 6 +-
153 files changed, 4049 insertions(+), 350 deletions(-)
create mode 100644 Documentation/ksplice.txt
create mode 100644 arch/x86/kernel/ksplice-arch.c
create mode 100644 include/linux/ksplice.h
create mode 100644 kernel/ksplice.c

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Next message: Tim Abbott: "[PATCH v2 3/4] Ksplice: Export symbols needed for Ksplice"
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