diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-05 12:25:15 +0100 |
|---|---|---|
| committer | Sami Tolvanen <samitolvanen@google.com> | 2016-09-29 10:52:56 -0700 |
| commit | 4dbc88bd2b6a74fd33483ee2593dcf2bd858eabe (patch) | |
| tree | bbcf01b55aafe8a83ff0a9f783d1f8ed75448a39 | |
| parent | 5dc2b7c7bb33138270ff9494be6cf334bd3d20e1 (diff) | |
FROMLIST: 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>
Change-Id: I927f14076ba94c83e609b19f46dd373287e11fc4
(cherry picked from commit 8cc1f33d2c9f206b6505bedba41aed2b33c203c0)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
| -rw-r--r-- | arch/arm64/xen/hypercall.S | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/arm64/xen/hypercall.S b/arch/arm64/xen/hypercall.S index 8bbe9401f4f0..6d6e4af1a4bf 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 +90,24 @@ ENTRY(privcmd_call) mov x2, x3 mov x3, x4 mov x4, x5 +#ifdef CONFIG_ARM64_SW_TTBR0_PAN + /* + * 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_enable_not_uao x6, x7 +#endif hvc XEN_IMM + +#ifdef CONFIG_ARM64_SW_TTBR0_PAN + /* + * Disable userspace access from kernel once the hyp call completed. + */ + uaccess_disable_not_uao x6 +#endif ret ENDPROC(privcmd_call); |