[PATCH v2 0/4] Static calls

[Josh Poimboeuf <jpoimboe@redhat.com>]

v2:
- fix STATIC_CALL_TRAMP() macro by using __PASTE() [Ard]
- rename optimized/unoptimized -> inline/out-of-line [Ard]
- tweak arch interfaces for PLT and add key->tramp field [Ard]
- rename 'poison' to 'defuse' and do it after all sites have been patched [Ard]
- fix .init handling [Ard, Steven]
- add CONFIG_HAVE_STATIC_CALL [Steven]
- make interfaces more consistent across configs to allow tracepoints to
  use them [Steven]
- move __ADDRESSABLE() to static_call() macro [Steven]
- prevent 2-byte jumps [Steven]
- add offset to asm-offsets.c instead of hard coding key->func offset
- add kernel_text_address() sanity check
- make __ADDRESSABLE() symbols truly unique

TODO:
- port Ard's arm64 patches to the new arch interfaces
- tracepoint performance testing

--------------------

These patches are related to two similar patch sets from Ard and Steve:

- https://lkml.kernel.org/r/20181005081333.15018-1-ard.biesheuvel@linaro.org
- https://lkml.kernel.org/r/20181006015110.653946300@goodmis.org

The code is also heavily inspired by the jump label code, as some of the
concepts are very similar.

There are three separate implementations, depending on what the arch
supports:

  1) CONFIG_HAVE_STATIC_CALL_INLINE: patched call sites - requires
     objtool and a small amount of arch code
  
  2) CONFIG_HAVE_STATIC_CALL_OUTLINE: patched trampolines - requires
     a small amount of arch code
  
  3) If no arch support, fall back to regular function pointers


Josh Poimboeuf (4):
  compiler.h: Make __ADDRESSABLE() symbol truly unique
  static_call: Add static call infrastructure
  x86/static_call: Add out-of-line static call implementation
  x86/static_call: Add inline static call implementation for x86-64

 arch/Kconfig                                  |  10 +
 arch/x86/Kconfig                              |   4 +-
 arch/x86/include/asm/static_call.h            |  52 +++
 arch/x86/kernel/Makefile                      |   1 +
 arch/x86/kernel/asm-offsets.c                 |   6 +
 arch/x86/kernel/static_call.c                 |  78 ++++
 include/asm-generic/vmlinux.lds.h             |  11 +
 include/linux/compiler.h                      |   2 +-
 include/linux/module.h                        |  10 +
 include/linux/static_call.h                   | 202 ++++++++++
 include/linux/static_call_types.h             |  19 +
 kernel/Makefile                               |   1 +
 kernel/module.c                               |   5 +
 kernel/static_call.c                          | 350 ++++++++++++++++++
 tools/objtool/Makefile                        |   3 +-
 tools/objtool/check.c                         | 126 ++++++-
 tools/objtool/check.h                         |   2 +
 tools/objtool/elf.h                           |   1 +
 .../objtool/include/linux/static_call_types.h |  19 +
 tools/objtool/sync-check.sh                   |   1 +
 20 files changed, 899 insertions(+), 4 deletions(-)
 create mode 100644 arch/x86/include/asm/static_call.h
 create mode 100644 arch/x86/kernel/static_call.c
 create mode 100644 include/linux/static_call.h
 create mode 100644 include/linux/static_call_types.h
 create mode 100644 kernel/static_call.c
 create mode 100644 tools/objtool/include/linux/static_call_types.h

-- 
2.17.2