This patch implements support for ARMv8.5-A Branch Target Identification (BTI), which is a control flow integrity protection feature introduced as part of the ARMv8.5-A extensions. This is mainly a repost based on v5.5-rc1. Changes: v4: - Dropped patch fixing existing documentation as it has already been merged. - Convert WARN_ON() to WARN_ON_ONCE() in "ELF: Add ELF program property parsing support". - Added display of guarded pages to ptdump. - Updated for conversion of exception handling from assembler to C. Notes: * GCC 9 can compile backwards-compatible BTI-enabled code with -mbranch-protection=bti or -mbranch-protection=standard. * Binutils trunk supports the new ELF note, but this wasn't in a release the last time I posted this series. (The situation _might_ have changed in the meantime...) Creation of a BTI-enabled binary requires _everything_ linked in to be BTI-enabled. For now ld --force-bti can be used to override this, but some things may break until the required C library support is in place. There is no straightforward way to mark a .s file as BTI-enabled: scraping the output from gcc -S works as a quick hack for now. readelf -n can be used to examing the program properties in an ELF file. * Runtime mmap() and mprotect() can be used to enable BTI on a page-by-page basis using the new PROT_BTI, but the code in the affected pages still needs to be written or compiled to contain the appopriate BTI landing pads. Dave Martin (11): ELF: UAPI and Kconfig additions for ELF program properties ELF: Add ELF program property parsing support mm: Reserve asm-generic prot flag 0x10 for arch use arm64: Basic Branch Target Identification support elf: Allow arch to tweak initial mmap prot flags arm64: elf: Enable BTI at exec based on ELF program properties arm64: BTI: Decode BYTPE bits when printing PSTATE arm64: unify native/compat instruction skipping arm64: traps: Shuffle code to eliminate forward declarations arm64: BTI: Reset BTYPE when skipping emulated instructions KVM: arm64: BTI: Reset BTYPE when skipping emulated instructions Mark Brown (1): arm64: mm: Display guarded pages in ptdump Documentation/arm64/cpu-feature-registers.rst | 2 + Documentation/arm64/elf_hwcaps.rst | 4 + arch/arm64/Kconfig | 29 ++++ arch/arm64/include/asm/cpucaps.h | 3 +- arch/arm64/include/asm/cpufeature.h | 6 + arch/arm64/include/asm/elf.h | 50 ++++++ arch/arm64/include/asm/esr.h | 2 +- arch/arm64/include/asm/exception.h | 1 + arch/arm64/include/asm/hwcap.h | 1 + arch/arm64/include/asm/kvm_emulate.h | 6 +- arch/arm64/include/asm/mman.h | 37 +++++ arch/arm64/include/asm/pgtable-hwdef.h | 1 + arch/arm64/include/asm/pgtable.h | 2 +- arch/arm64/include/asm/ptrace.h | 8 + arch/arm64/include/asm/sysreg.h | 4 + arch/arm64/include/uapi/asm/hwcap.h | 1 + arch/arm64/include/uapi/asm/mman.h | 9 ++ arch/arm64/include/uapi/asm/ptrace.h | 1 + arch/arm64/kernel/cpufeature.c | 33 ++++ arch/arm64/kernel/cpuinfo.c | 1 + arch/arm64/kernel/entry-common.c | 11 ++ arch/arm64/kernel/process.c | 36 ++++- arch/arm64/kernel/ptrace.c | 2 +- arch/arm64/kernel/signal.c | 16 ++ arch/arm64/kernel/syscall.c | 18 +++ arch/arm64/kernel/traps.c | 127 +++++++-------- arch/arm64/mm/dump.c | 5 + fs/Kconfig.binfmt | 6 + fs/binfmt_elf.c | 145 +++++++++++++++++- fs/compat_binfmt_elf.c | 4 + include/linux/elf.h | 43 ++++++ include/linux/mm.h | 3 + include/uapi/asm-generic/mman-common.h | 1 + include/uapi/linux/elf.h | 11 ++ 34 files changed, 554 insertions(+), 75 deletions(-) create mode 100644 arch/arm64/include/asm/mman.h create mode 100644 arch/arm64/include/uapi/asm/mman.h -- 2.20.1
