diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-05 12:25:15 +0100 |
|---|---|---|
| committer | Amit Pundir <amit.pundir@linaro.org> | 2017-01-16 16:10:03 +0530 |
| commit | 1324e7abf8b2dc139a135e89a56c5704830c52ce (patch) | |
| tree | c1676340e02abc5ed85753f9b4558d8adbebca08 | |
| parent | eac2c1f1c8e64d88f404a11c370c6d777eef95a6 (diff) | |
UPSTREAM: arm64: xen: Enable user access before a privcmd hvc call
Privcmd calls are issued by the userspace. The kernel needs to enable
access to TTBR0_EL1 as the hypervisor would issue stage 1 translations
to user memory via AT instructions. Since AT instructions are not
affected by the PAN bit (ARMv8.1), we only need the explicit
uaccess_enable/disable if the TTBR0 PAN option is enabled.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
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>
Bug: 31432001
Change-Id: I64d827923d869c1868702c8a18efa99ea91d3151
(cherry picked from commit 9cf09d68b89ae5fe0261dcc69464bcc676900af6)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
| -rw-r--r-- | arch/arm64/xen/hypercall.S | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/arm64/xen/hypercall.S b/arch/arm64/xen/hypercall.S index 8bbe9401f4f0..b96db5dafec4 100644 --- a/arch/arm64/xen/hypercall.S +++ b/arch/arm64/xen/hypercall.S @@ -49,6 +49,7 @@ #include <linux/linkage.h> #include <asm/assembler.h> +#include <asm/uaccess.h> #include <xen/interface/xen.h> @@ -89,6 +90,20 @@ ENTRY(privcmd_call) mov x2, x3 mov x3, x4 mov x4, x5 + /* + * Privcmd calls are issued by the userspace. The kernel needs to + * enable access to TTBR0_EL1 as the hypervisor would issue stage 1 + * translations to user memory via AT instructions. Since AT + * instructions are not affected by the PAN bit (ARMv8.1), we only + * need the explicit uaccess_enable/disable if the TTBR0 PAN emulation + * is enabled (it implies that hardware UAO and PAN disabled). + */ + uaccess_ttbr0_enable x6, x7 hvc XEN_IMM + + /* + * Disable userspace access from kernel once the hyp call completed. + */ + uaccess_ttbr0_disable x6 ret ENDPROC(privcmd_call); |