diff options
| author | James Morse <james.morse@arm.com> | 2016-02-05 15:58:48 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-02-18 18:27:04 +0100 |
| commit | 57f4959bad0a154aeca125b7d38d1d9471a12422 (patch) | |
| tree | 6d75f86840bb0bd2d3f4928993f696c44e2033c0 /arch/arm64/lib/clear_user.S | |
| parent | arm64: add ARMv8.2 id_aa64mmfr2 boiler plate (diff) | |
| download | linux-57f4959bad0a154aeca125b7d38d1d9471a12422.tar.xz linux-57f4959bad0a154aeca125b7d38d1d9471a12422.zip | |
arm64: kernel: Add support for User Access Override
'User Access Override' is a new ARMv8.2 feature which allows the
unprivileged load and store instructions to be overridden to behave in
the normal way.
This patch converts {get,put}_user() and friends to use ldtr*/sttr*
instructions - so that they can only access EL0 memory, then enables
UAO when fs==KERNEL_DS so that these functions can access kernel memory.
This allows user space's read/write permissions to be checked against the
page tables, instead of testing addr<USER_DS, then using the kernel's
read/write permissions.
Signed-off-by: James Morse <james.morse@arm.com>
[catalin.marinas@arm.com: move uao_thread_switch() above dsb()]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/lib/clear_user.S')
| -rw-r--r-- | arch/arm64/lib/clear_user.S | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S index a9723c71c52b..3f950b677c07 100644 --- a/arch/arm64/lib/clear_user.S +++ b/arch/arm64/lib/clear_user.S @@ -39,20 +39,20 @@ ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_HAS_PAN, \ subs x1, x1, #8 b.mi 2f 1: -USER(9f, str xzr, [x0], #8 ) +uao_user_alternative 9f, str, sttr, xzr, x0, 8 subs x1, x1, #8 b.pl 1b 2: adds x1, x1, #4 b.mi 3f -USER(9f, str wzr, [x0], #4 ) +uao_user_alternative 9f, str, sttr, wzr, x0, 4 sub x1, x1, #4 3: adds x1, x1, #2 b.mi 4f -USER(9f, strh wzr, [x0], #2 ) +uao_user_alternative 9f, strh, sttrh, wzr, x0, 2 sub x1, x1, #2 4: adds x1, x1, #1 b.mi 5f -USER(9f, strb wzr, [x0] ) +uao_user_alternative 9f, strb, sttrb, wzr, x0, 0 5: mov x0, #0 ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_HAS_PAN, \ CONFIG_ARM64_PAN) |