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| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-01 17:53:00 +0200 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-21 19:48:53 +0100 |
| commit | 4b65a5db362783ab4b04ca1c1d2ad70ed9b0ba2a (patch) | |
| tree | 56196f2fa7dbe5a41061b1aed297704ef7e2bbea /arch/arm64/kernel/entry.S | |
| parent | arm64: Factor out TTBR0_EL1 post-update workaround into a specific asm macro (diff) | |
| download | linux-4b65a5db362783ab4b04ca1c1d2ad70ed9b0ba2a.tar.xz linux-4b65a5db362783ab4b04ca1c1d2ad70ed9b0ba2a.zip | |
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/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 6349a8324b4f..b7db3766a312 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -183,10 +183,6 @@ alternative_else_nop_endif eret // return to kernel .endm - .macro get_thread_info, rd - mrs \rd, sp_el0 - .endm - .macro irq_stack_entry mov x19, sp // preserve the original sp |