This series implements support for emitting the data structures associated with jump tables as 32-bit relative references instead of absolute references, which take up more space on builds that target 64-bit architectures, or implement self relocation [or both]. This series enables it for arm64 and x86, although other architectures might benefit as well. Patch #1 does some preparatory refactoring before patch #2 introduces the generic pieces required for using relative references. Patch #3 wires everything up for arm64. Patch #4 introduces support for handling 64-bit place relative relocations on x86_64 (see 'Changes since v1' below) For x86, patch #5 applies some preparatory changes for the arch specific jump label C code, which is a lot more involved than on arm64, which is why it is split off in this case. Patch #6 wires it up for x86 as well. Patch #7 and #8 implement the changes so that the jump_entry arrays reside in ro_after_init memory rather than remain fully writable all of the time. Patch #9 enables the feature for s390 (contributed by Heiko) Changes since v2: - fix breakage in user mode x86 kernel due to missing definition of the R_X86_64_PC64 symbolic constant - add acks from Jessica and Kees - add s390 enablement patch Changes since v1: - change the relative reference to the static key to a 64-bit wide one on 64 bit architectures; this is necessary on arm64, which allows modules to reside anywhere within a 4 GB window covering the core kernel text, which means a 32-bit signed quantity with its +/- 2 GB range is insufficient. Note that x86_64 changes are in preparation that widen the relocation range as well (using the PIE linker), so I assumed that the same change is appropriate for x86 as well. - add patch #4 to handle the relocations emitted by the compiler as a result of the change above - added patches to move the jump_entry arrays to ro_after_init memory, so that they are not as easily corrupted or manipulated. - add Will's ack to patch #3 Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> Cc: Jessica Yu <jeyu@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Ard Biesheuvel (8): kernel/jump_label: abstract jump_entry member accessors kernel/jump_label: implement generic support for relative references arm64/kernel: jump_label: switch to relative references x86: add support for 64-bit place relative relocations x86: jump_label: switch to jump_entry accessors x86/kernel: jump_table: use relative references jump_label: annotate entries that operate on __init code earlier jump_table: move entries into ro_after_init region Heiko Carstens (1): s390/jump_label: switch to relative references arch/Kconfig | 3 + arch/arm64/Kconfig | 1 + arch/arm64/include/asm/jump_label.h | 38 ++++---- arch/arm64/kernel/jump_label.c | 6 +- arch/s390/Kconfig | 1 + arch/s390/include/asm/jump_label.h | 40 ++++---- arch/s390/kernel/jump_label.c | 11 ++- arch/s390/kernel/vmlinux.lds.S | 1 + arch/x86/Kconfig | 1 + arch/x86/include/asm/elf.h | 3 +- arch/x86/include/asm/jump_label.h | 24 ++--- arch/x86/kernel/jump_label.c | 62 +++++------- arch/x86/kernel/module.c | 6 ++ arch/x86/tools/relocs.c | 10 ++ arch/x86/um/asm/elf.h | 3 +- include/asm-generic/vmlinux.lds.h | 11 ++- include/linux/jump_label.h | 65 ++++++++++++- init/main.c | 1 - kernel/jump_label.c | 100 +++++++++----------- kernel/module.c | 9 ++ tools/objtool/special.c | 4 +- 21 files changed, 226 insertions(+), 174 deletions(-) -- 2.17.1
