diff options
author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-05 12:25:15 +0100 |
---|---|---|
committer | Sami Tolvanen <samitolvanen@google.com> | 2017-01-04 10:56:22 -0800 |
commit | 9fcab0c5b4280c6fc860b23ae6335712a4eb77c6 (patch) | |
tree | dfde6f189eaeae24c332b59d72dd395a238659fa | |
parent | 17080bcf2c6ec3e34b36f68d7e4b37b55ff9d16f (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); |