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Subject[PATCH v4 00/12] arm64: ARMv8.5-A: Branch Target Identification support
Date
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

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