diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-01 16:53:00 +0100 |
|---|---|---|
| committer | Amit Pundir <amit.pundir@linaro.org> | 2016-10-12 17:34:22 +0530 |
| commit | fb82efd29dd555a19ee378a16ad6fabbb4fcc951 (patch) | |
| tree | 82129b1322b1bb4d035172d994ae510aab804522 /arch/arm64/include/asm/assembler.h | |
| parent | bb8653ae4be48db54ab7e2a7959e71c8469ab7f5 (diff) | |
FROMLIST: 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>
Change-Id: Idf09a870b8612dce23215bce90d88781f0c0c3aa
(cherry picked from commit 940d37234182d2675ab8ab46084840212d735018)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Diffstat (limited to 'arch/arm64/include/asm/assembler.h')
| -rw-r--r-- | arch/arm64/include/asm/assembler.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index 9d3e77a5cf07..aeb4554b3af3 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -53,6 +53,15 @@ msr daifclr, #2 .endm + .macro save_and_disable_irq, flags + mrs \flags, daif + msr daifset, #2 + .endm + + .macro restore_irq, flags + msr daif, \flags + .endm + /* * Enable and disable debug exceptions. */ @@ -363,6 +372,13 @@ alternative_endif .endm /* + * Return the current thread_info. + */ + .macro get_thread_info, rd + mrs \rd, sp_el0 + .endm + +/* * Errata workaround post TTBR0_EL1 update. */ .macro post_ttbr0_update_workaround |