[PATCH v2 0/5] arm64: kernel: Add support for User Access Override
From: james.morse@arm.com (James Morse)
Date: 2016-02-05 14:58:45
This series adds support for User Access Override (UAO; part of the ARMv8.2 Extensions[0]). When enabled, this causes the get_user() accessors to use the unprivileged load/store instructions. When addr_limit is set to KERNEL_DS, we set the override bit allowing privileged access. Because the unprivileged instructions don't trip PAN, the last patch changes which 'alternative' values are swapped in, allowing PAN to be left enabled during get_user() and friends. This series can be retrieved from: git://linux-arm.org/linux-jm.git -b uao/v2 Comments welcome, James Since v1: * Moved id register definition into the boiler-plate patch. * Moved cpu_enable_uao() into mm/fault.c [0] https://community.arm.com/groups/processors/blog/2016/01/05/armv8-a-architecture-evolution [v1] https://lwn.net/Articles/674445/ James Morse (5): arm64: cpufeature: Change read_cpuid() to use sysreg's mrs_s macro arm64: add ARMv8.2 id_aa64mmfr2 boiler plate arm64: kernel: Add support for User Access Override arm64: cpufeature: Test 'matches' pointer to find the end of the list arm64: kernel: Don't toggle PAN on systems with UAO arch/arm64/Kconfig | 21 +++++++ arch/arm64/include/asm/alternative.h | 72 +++++++++++++++++++++++ arch/arm64/include/asm/cpu.h | 1 + arch/arm64/include/asm/cpufeature.h | 6 +- arch/arm64/include/asm/cputype.h | 20 ++++--- arch/arm64/include/asm/processor.h | 1 + arch/arm64/include/asm/sysreg.h | 7 +++ arch/arm64/include/asm/thread_info.h | 6 ++ arch/arm64/include/asm/uaccess.h | 52 +++++++++++------ arch/arm64/include/uapi/asm/ptrace.h | 1 + arch/arm64/kernel/cpufeature.c | 107 +++++++++++++++++++++++------------ arch/arm64/kernel/cpuinfo.c | 55 +++++++++--------- arch/arm64/kernel/process.c | 20 +++++++ arch/arm64/lib/clear_user.S | 12 ++-- arch/arm64/lib/copy_from_user.S | 12 ++-- arch/arm64/lib/copy_in_user.S | 20 +++---- arch/arm64/lib/copy_to_user.S | 12 ++-- arch/arm64/mm/context.c | 2 +- arch/arm64/mm/fault.c | 34 +++++++++-- 19 files changed, 337 insertions(+), 124 deletions(-) -- 2.6.2