diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-01 16:53:00 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-21 18:48:53 +0000 |
| commit | 4b65a5db362783ab4b04ca1c1d2ad70ed9b0ba2a (patch) | |
| tree | 56196f2fa7dbe5a41061b1aed297704ef7e2bbea /arch/arm64/kernel/vmlinux.lds.S | |
| parent | f33bcf03e6079668da6bf4eec4a7dcf9289131d0 (diff) | |
arm64: Introduce uaccess_{disable,enable} functionality based on TTBR0_EL1
This patch adds the uaccess macros/functions to disable access to user
space by setting TTBR0_EL1 to a reserved zeroed page. Since the value
written to TTBR0_EL1 must be a physical address, for simplicity this
patch introduces a reserved_ttbr0 page at a constant offset from
swapper_pg_dir. The uaccess_disable code uses the ttbr1_el1 value
adjusted by the reserved_ttbr0 offset.
Enabling access to user is done by restoring TTBR0_EL1 with the value
from the struct thread_info ttbr0 variable. Interrupts must be disabled
during the uaccess_ttbr0_enable code to ensure the atomicity of the
thread_info.ttbr0 read and TTBR0_EL1 write. This patch also moves the
get_thread_info asm macro from entry.S to assembler.h for reuse in the
uaccess_ttbr0_* macros.
Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/vmlinux.lds.S')
| -rw-r--r-- | arch/arm64/kernel/vmlinux.lds.S | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 1105aab1e6d6..b8deffa9e1bf 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -216,6 +216,11 @@ SECTIONS swapper_pg_dir = .; . += SWAPPER_DIR_SIZE; +#ifdef CONFIG_ARM64_SW_TTBR0_PAN + reserved_ttbr0 = .; + . += RESERVED_TTBR0_SIZE; +#endif + _end = .; STABS_DEBUG |