Posting this for *after* the merge window.
This v5 addresses feedback from the last v4 series [0] about 4 months ago.
The first RFC series was posted just 1 year ago, last December 15 [1], its
been a long way coming. The largest amount of feedback from the v4 series came
from Nicholas Piggin, I've also made a few more minor changes and enhancements.
Because I have gone on different conferences talking about this work I've
jotted down in a white-paper form what this is all about and I've used it as
basis for a huge brush up on the documentation. I have not included the
paper into the tree as I think the documentation now stands for itself. The
paper may be useful for those wanted a huge verbose explanation to things
with much more in depth analysis and review of history [2].
I've split up the linker table patches in two groups to make it easier to
review, the first set (this) is for the kernel work, the second set is for the
tools/ userspace sandbox. If you would like to review all the changes in git
form you can yank them off of my linux-next 20161221-linker-tables-v5 branch on
kernel.org [3], please however note that the last patch on that tree was *not*
submitted upstream, it was used to force test 0-day and also Guenter's testbed
to force-enable and run the tests. You can disregard that patch unless you also
want to force test things :)
The biggest changes since v4 series worth noting:
o Ended up using two dots (..) to separate the new sections to avoid conflicts
with compiler generated sections, so we have: .text..rng.*, .data..tbl.*,
etc.
o Remove all the macro magic for section names. We now expect you to
spell out each section manually. So no more SECTION_TEXT, for instance,
for instance, we use just naked .text.
o Adds a section linker table selftest driver. I have a debug out of tree
patch used which was applied when testing which force enables the driver
to be built in. This has been successfully run time tested against the
following architectures:
alpha arc arcv2 arm arm64 blackfin c6x
cris crisv32 frv h8300 hexagon i386 ia64
m32r m68k m68k_nommu metag microblaze mips_22 mips_24
mips_25 mn10300 nios2 openrisc parisc parisc64 powerpc
s390 score sh sparc32 sparc64 tile um
unicore32 x86_64 xtensa
The only architecture that was not tested was avr32 and that is because
linux-next fails to compile on it. I'd like to greatly thank Guenter Roeck
for his help with testing.
o A documentation revamp, to align what I hard originally written in the
v4 series more in alignment with the the ELF specifications. Also properly
document mark_rodata_ro().
o Recruited Josh Poimboeuf and hpa as co-mainters of the general section
stuff. For section ranges and linker tables it will be both me and hpa
reviewing things. At Plumbers I spoke with Arnd and he would prefer changes
to go in through each respective tree that needs each change, so no new
tree is created. We'll just review and Ack/nack changes.
Happy holidays, and may the force be with you all...
Oh and lastly, a quick summary of the gains of having an API for all this.
First the obvious gains:
o Allows us to just use plain C code to add new program specific
ELF sections
o Makes it less error prone to add new sections
Then the not so obvious immediate gains:
o Helps simplify initialization code
o Helps optionally avoid code bit-rot (see commit "kbuild: enable option to
force compile force-obj-y and force-lib-y)
o Enables link time ordering which can help make an extremely lightweight
dependency annotations explicit (for this refer to the tools/linker-tables/
example where I've demo'd simplfying Xen PV init code, which has caused
tons of regressions over time due to the lack of explicit dependency
annotations due to the sloppy Xen PV entry path; this is not going away
any time soon)
Not so obvious long term gains:
o Run time ordering customization are still possible (this is really long
term but we already have one precedent in the kernel that does memmove()
on entries on a section per some dependency heuristic.)
o May help prevent use of dead code by either free'ing / nop'ing, no exec
or whatever sections which we know should definitely not run.
o Can easily increase the levels of initialization in the kernel without
much changes (refer to tools/linker-tables/ for an example init with
linker tables). I've seen a few cases where we've already run out of space
to get init right in a few subsystems. This not only allows this but also
allows subsystems to define their own custom levels of init if they wanted
for their own things.
o Synthetic functions: enables custom C / asm functions which could help
add new functionality (see synth_init_or() on tools/linker-tables/drivers/synth/main.c)
I've been hinted this can help with RAID6 support
o Self modifying consts (see ps_shr() on tools/linker-tables/drivers/synth/main.c)
[0] https://lkml.kernel.org/r/1471642454-5679-1-git-send-email-mcgrof@xxxxxxxxxx
[1] https://lkml.kernel.org/r/1450217797-19295-1-git-send-email-mcgrof@xxxxxxxxxxxxxxxx
[2] http://drvbp1.linux-foundation.org/~mcgrof/papers/2016/12/21/linker-tables-20161221.pdf
[3] https://git.kernel.org/cgit/linux/kernel/git/mcgrof/linux-next.git/log/?h=20161221-linker-tables-v5
Luis R. Rodriguez (14):
generic-sections: add section core helpers
xtensa: skip adding literal when SORT() is used
ranges.h: add helpers to build and identify Linux section ranges
tables.h: add linker table support
kbuild: enable option to force compile force-obj-y and force-lib-y
firmware/Makefile: force recompilation if makefile changes
firmware: port built-in section to linker table
jump_label: move guard #endif down where it belongs
jump_label: port __jump_table to linker tables
dynamic_debug: port to use linker tables
kprobes: move kprobe declarations to asm-generic/kprobes.h
kprobes: port .kprobes.text to section range
kprobes: port blacklist kprobes to linker table
lib: add linker tables test driver
Documentation/index.rst | 1 +
Documentation/kbuild/makefiles.txt | 36 ++
Documentation/sections/background.rst | 105 ++++
Documentation/sections/conf.py | 4 +
Documentation/sections/index.rst | 19 +
Documentation/sections/linker-tables.rst | 227 +++++++++
Documentation/sections/ranges.rst | 74 +++
Documentation/sections/section-core.rst | 153 ++++++
MAINTAINERS | 32 ++
arch/alpha/include/asm/Kbuild | 4 +
arch/arc/include/asm/Kbuild | 3 +
arch/arc/include/asm/kprobes.h | 6 +-
arch/arc/kernel/vmlinux.lds.S | 1 -
arch/arm/include/asm/Kbuild | 3 +
arch/arm/include/asm/jump_label.h | 6 +-
arch/arm/include/asm/kprobes.h | 4 +
arch/arm/kernel/entry-armv.S | 3 +-
arch/arm/kernel/vmlinux-xip.lds.S | 1 -
arch/arm/kernel/vmlinux.lds.S | 1 -
arch/arm/probes/decode.h | 1 +
arch/arm64/include/asm/Kbuild | 3 +
arch/arm64/include/asm/jump_label.h | 6 +-
arch/arm64/include/asm/kprobes.h | 4 +
arch/arm64/kernel/armv8_deprecated.c | 1 +
arch/arm64/kernel/insn.c | 1 +
arch/arm64/kernel/probes/decode-insn.h | 2 +
arch/arm64/kernel/probes/kprobes.c | 4 +-
arch/arm64/kernel/vmlinux.lds.S | 1 -
arch/avr32/include/asm/Kbuild | 3 +
arch/avr32/include/asm/kprobes.h | 7 +-
arch/avr32/kernel/entry-avr32b.S | 13 +-
arch/avr32/kernel/vmlinux.lds.S | 1 -
arch/blackfin/include/asm/Kbuild | 4 +
arch/blackfin/kernel/vmlinux.lds.S | 1 -
arch/c6x/include/asm/Kbuild | 3 +
arch/c6x/include/asm/tables.h | 26 +
arch/c6x/kernel/vmlinux.lds.S | 1 -
arch/cris/include/asm/Kbuild | 4 +
arch/frv/include/asm/Kbuild | 4 +
arch/h8300/include/asm/Kbuild | 4 +
arch/hexagon/include/asm/Kbuild | 4 +
arch/hexagon/kernel/vmlinux.lds.S | 1 -
arch/ia64/include/asm/Kbuild | 3 +
arch/ia64/include/asm/kprobes.h | 12 +-
arch/ia64/kernel/jprobes.S | 3 +-
arch/ia64/kernel/vmlinux.lds.S | 1 -
arch/ia64/lib/flush.S | 6 +-
arch/m32r/include/asm/Kbuild | 4 +
arch/m68k/include/asm/Kbuild | 4 +
arch/metag/include/asm/Kbuild | 4 +
arch/metag/kernel/vmlinux.lds.S | 1 -
arch/microblaze/include/asm/Kbuild | 4 +
arch/microblaze/kernel/vmlinux.lds.S | 1 -
arch/mips/include/asm/Kbuild | 3 +
arch/mips/include/asm/jump_label.h | 6 +-
arch/mips/include/asm/kprobes.h | 6 +-
arch/mips/kernel/vmlinux.lds.S | 1 -
arch/mn10300/include/asm/Kbuild | 3 +
arch/mn10300/include/asm/kprobes.h | 7 +-
arch/mn10300/kernel/vmlinux.lds.S | 1 -
arch/nios2/include/asm/Kbuild | 4 +
arch/nios2/kernel/vmlinux.lds.S | 1 -
arch/openrisc/include/asm/Kbuild | 4 +
arch/openrisc/kernel/vmlinux.lds.S | 1 -
arch/parisc/include/asm/Kbuild | 4 +
arch/parisc/kernel/vmlinux.lds.S | 1 -
arch/powerpc/include/asm/Kbuild | 3 +
arch/powerpc/include/asm/jump_label.h | 8 +-
arch/powerpc/include/asm/kprobes.h | 3 +
arch/powerpc/include/asm/ppc_asm.h | 3 +-
arch/powerpc/kernel/vmlinux.lds.S | 3 +-
arch/s390/include/asm/Kbuild | 3 +
arch/s390/include/asm/jump_label.h | 6 +-
arch/s390/include/asm/kprobes.h | 7 +-
arch/s390/kernel/entry.S | 5 +-
arch/s390/kernel/kprobes.c | 6 +-
arch/s390/kernel/mcount.S | 3 +-
arch/s390/kernel/vmlinux.lds.S | 1 -
arch/score/include/asm/Kbuild | 4 +
arch/score/kernel/vmlinux.lds.S | 1 -
arch/sh/include/asm/Kbuild | 3 +
arch/sh/include/asm/kprobes.h | 5 +-
arch/sh/kernel/vmlinux.lds.S | 1 -
arch/sparc/include/asm/Kbuild | 3 +
arch/sparc/include/asm/jump_label.h | 6 +-
arch/sparc/include/asm/kprobes.h | 10 +-
arch/sparc/kernel/vmlinux.lds.S | 1 -
arch/sparc/mm/ultra.S | 3 +-
arch/tile/include/asm/Kbuild | 3 +
arch/tile/include/asm/jump_label.h | 5 +-
arch/tile/include/asm/kprobes.h | 6 +-
arch/tile/kernel/vmlinux.lds.S | 1 -
arch/um/include/asm/Kbuild | 4 +
arch/unicore32/include/asm/Kbuild | 3 +
arch/unicore32/include/asm/section-core.h | 19 +
arch/x86/include/asm/Kbuild | 3 +
arch/x86/include/asm/asm.h | 4 +-
arch/x86/include/asm/jump_label.h | 10 +-
arch/x86/include/asm/kprobes.h | 9 +-
arch/x86/kernel/cpu/microcode/core.c | 8 +-
arch/x86/kernel/kprobes/core.c | 11 +-
arch/x86/kernel/vmlinux.lds.S | 1 -
arch/x86/tools/relocs.c | 4 +
arch/xtensa/include/asm/Kbuild | 4 +
arch/xtensa/kernel/Makefile | 8 +-
drivers/base/firmware_class.c | 12 +-
firmware/Makefile | 6 +-
include/asm-generic/kprobes.h | 26 +
include/asm-generic/ranges.h | 93 ++++
include/asm-generic/section-core.h | 348 +++++++++++++
include/asm-generic/sections.h | 4 +-
include/asm-generic/tables.h | 48 ++
include/asm-generic/vmlinux.lds.h | 47 +-
include/linux/compiler.h | 8 -
include/linux/dynamic_debug.h | 5 +-
include/linux/init.h | 89 +++-
include/linux/jump_label.h | 8 +-
include/linux/kprobes.h | 24 +-
include/linux/ranges.h | 183 +++++++
include/linux/sections.h | 87 ++++
include/linux/tables.h | 683 +++++++++++++++++++++++++
init/Kconfig | 22 +
kernel/jump_label.c | 17 +-
kernel/kprobes.c | 17 +-
lib/Kconfig.debug | 6 +
lib/Makefile | 1 +
lib/dynamic_debug.c | 13 +-
lib/test_linktables/Makefile | 13 +
lib/test_linktables/test-linktables-00.c | 27 +
lib/test_linktables/test-linktables-01.c | 27 +
lib/test_linktables/test-linktables-02.c | 27 +
lib/test_linktables/test-linktables-03.c | 27 +
lib/test_linktables/test-linktables-04.c | 27 +
lib/test_linktables/test-linktables.c | 801 ++++++++++++++++++++++++++++++
lib/test_linktables/test-linktables.h | 48 ++
scripts/Makefile.build | 7 +-
scripts/Makefile.clean | 2 +
scripts/Makefile.lib | 11 +
scripts/mod/modpost.c | 2 +-
scripts/module-common.lds | 2 +
scripts/recordmcount.c | 2 +-
scripts/recordmcount.pl | 2 +-
tools/objtool/special.c | 2 +-
143 files changed, 3632 insertions(+), 200 deletions(-)
create mode 100644 Documentation/sections/background.rst
create mode 100644 Documentation/sections/conf.py
create mode 100644 Documentation/sections/index.rst
create mode 100644 Documentation/sections/linker-tables.rst
create mode 100644 Documentation/sections/ranges.rst
create mode 100644 Documentation/sections/section-core.rst
create mode 100644 arch/c6x/include/asm/tables.h
create mode 100644 arch/unicore32/include/asm/section-core.h
create mode 100644 include/asm-generic/kprobes.h
create mode 100644 include/asm-generic/ranges.h
create mode 100644 include/asm-generic/section-core.h
create mode 100644 include/asm-generic/tables.h
create mode 100644 include/linux/ranges.h
create mode 100644 include/linux/sections.h
create mode 100644 include/linux/tables.h
create mode 100644 lib/test_linktables/Makefile
create mode 100644 lib/test_linktables/test-linktables-00.c
create mode 100644 lib/test_linktables/test-linktables-01.c
create mode 100644 lib/test_linktables/test-linktables-02.c
create mode 100644 lib/test_linktables/test-linktables-03.c
create mode 100644 lib/test_linktables/test-linktables-04.c
create mode 100644 lib/test_linktables/test-linktables.c
create mode 100644 lib/test_linktables/test-linktables.h
--
2.10.1
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