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| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-05 12:25:15 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-21 18:48:55 +0000 |
| commit | 9cf09d68b89ae5fe0261dcc69464bcc676900af6 (patch) | |
| tree | a9f9ad57e9d9e6b8e09dfb7b9b3ae4df64566629 /arch/arm64/xen | |
| parent | 786889636ad75296c213547d1ca656af4c59f390 (diff) | |
| download | linux-9cf09d68b89ae5fe0261dcc69464bcc676900af6.tar.bz2 | |
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>
Diffstat (limited to 'arch/arm64/xen')
| -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 329c8027b0a9..b41aff25426d 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> @@ -91,6 +92,20 @@ 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); |