[PATCH 1/3] arm/arm64/xen: use C inlines for privcmd_call

Pavel Tatashin
2019-11-27T18:45:02Z

privcmd_call requires to enable access to userspace for the
duration of the hypercall.

Currently, this is done via assembly macros. Change it to C
inlines instead.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
---
arch/arm/include/asm/assembler.h | 2 +-
arch/arm/include/asm/xen/hypercall.h | 10 +++++++++
arch/arm/xen/enlighten.c | 2 +-
arch/arm/xen/hypercall.S | 4 ++--
arch/arm64/include/asm/xen/hypercall.h | 28 ++++++++++++++++++++++++++
arch/arm64/xen/hypercall.S | 19 ++---------------
include/xen/arm/hypercall.h | 12 +++++------
7 files changed, 50 insertions(+), 27 deletions(-)

diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 99929122dad7..8e9262a0f016 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -480,7 +480,7 @@ THUMB( orr \reg , \reg , #PSR_T_BIT )
.macro uaccess_disable, tmp, isb=1
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
/*
- * Whenever we re-enter userspace, the domains should always be
+ * Whenever we re-enter kernel, the domains should always be
* set appropriately.
*/
mov \tmp, #DACR_UACCESS_DISABLE
diff --git a/arch/arm/include/asm/xen/hypercall.h b/arch/arm/include/asm/xen/hypercall.h
index 3522cbaed316..cac5bd9ef519 100644
--- a/arch/arm/include/asm/xen/hypercall.h
+++ b/arch/arm/include/asm/xen/hypercall.h
@@ -1 +1,11 @@
+#ifndef _ASM_ARM_XEN_HYPERCALL_H
+#define _ASM_ARM_XEN_HYPERCALL_H
#include <xen/arm/hypercall.h>
+
+static inline long privcmd_call(unsigned int call, unsigned long a1,
+ unsigned long a2, unsigned long a3,
+ unsigned long a4, unsigned long a5)
+{
+ return arch_privcmd_call(call, a1, a2, a3, a4, a5);
+}
+#endif /* _ASM_ARM_XEN_HYPERCALL_H */
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index dd6804a64f1a..e87280c6d25d 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -440,4 +440,4 @@ EXPORT_SYMBOL_GPL(HYPERVISOR_platform_op_raw);
EXPORT_SYMBOL_GPL(HYPERVISOR_multicall);
EXPORT_SYMBOL_GPL(HYPERVISOR_vm_assist);
EXPORT_SYMBOL_GPL(HYPERVISOR_dm_op);
-EXPORT_SYMBOL_GPL(privcmd_call);
+EXPORT_SYMBOL_GPL(arch_privcmd_call);
diff --git a/arch/arm/xen/hypercall.S b/arch/arm/xen/hypercall.S
index b11bba542fac..277078c7da49 100644
--- a/arch/arm/xen/hypercall.S
+++ b/arch/arm/xen/hypercall.S
@@ -94,7 +94,7 @@ HYPERCALL2(multicall);
HYPERCALL2(vm_assist);
HYPERCALL3(dm_op);

-ENTRY(privcmd_call)
+ENTRY(arch_privcmd_call)
stmdb sp!, {r4}
mov r12, r0
mov r0, r1
@@ -119,4 +119,4 @@ ENTRY(privcmd_call)

ldm sp!, {r4}
ret lr
-ENDPROC(privcmd_call);
+ENDPROC(arch_privcmd_call);
diff --git a/arch/arm64/include/asm/xen/hypercall.h b/arch/arm64/include/asm/xen/hypercall.h
index 3522cbaed316..1a74fb28607f 100644
--- a/arch/arm64/include/asm/xen/hypercall.h
+++ b/arch/arm64/include/asm/xen/hypercall.h
@@ -1 +1,29 @@
+#ifndef _ASM_ARM64_XEN_HYPERCALL_H
+#define _ASM_ARM64_XEN_HYPERCALL_H
#include <xen/arm/hypercall.h>
+#include <linux/uaccess.h>
+
+static inline long privcmd_call(unsigned int call, unsigned long a1,
+ unsigned long a2, unsigned long a3,
+ unsigned long a4, unsigned long a5)
+{
+ long rv;
+
+ /*
+ * 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();
+ rv = arch_privcmd_call(call, a1, a2, a3, a4, a5);
+ /*
+ * Disable userspace access from kernel once the hyp call completed.
+ */
+ uaccess_ttbr0_disable();
+
+ return rv;
+}
+#endif /* _ASM_ARM64_XEN_HYPERCALL_H */
diff --git a/arch/arm64/xen/hypercall.S b/arch/arm64/xen/hypercall.S
index c5f05c4a4d00..921611778d2a 100644
--- a/arch/arm64/xen/hypercall.S
+++ b/arch/arm64/xen/hypercall.S
@@ -49,7 +49,6 @@

#include <linux/linkage.h>
#include <asm/assembler.h>
-#include <asm/asm-uaccess.h>
#include <xen/interface/xen.h>

@@ -86,27 +85,13 @@ HYPERCALL2(multicall);
HYPERCALL2(vm_assist);
HYPERCALL3(dm_op);

-ENTRY(privcmd_call)
+ENTRY(arch_privcmd_call)
mov x16, x0
mov x0, x1
mov x1, x2
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, x8
hvc XEN_IMM
-
- /*
- * Disable userspace access from kernel once the hyp call completed.
- */
- uaccess_ttbr0_disable x6, x7
ret
-ENDPROC(privcmd_call);
+ENDPROC(arch_privcmd_call);
diff --git a/include/xen/arm/hypercall.h b/include/xen/arm/hypercall.h
index b40485e54d80..624c8ad7e42a 100644
--- a/include/xen/arm/hypercall.h
+++ b/include/xen/arm/hypercall.h
@@ -30,8 +30,8 @@
* IN THE SOFTWARE.
*/

-#ifndef _ASM_ARM_XEN_HYPERCALL_H
-#define _ASM_ARM_XEN_HYPERCALL_H
+#ifndef _ARM_XEN_HYPERCALL_H
+#define _ARM_XEN_HYPERCALL_H

#include <linux/bug.h>

@@ -41,9 +41,9 @@

struct xen_dm_op_buf;

-long privcmd_call(unsigned call, unsigned long a1,
- unsigned long a2, unsigned long a3,
- unsigned long a4, unsigned long a5);
+long arch_privcmd_call(unsigned int call, unsigned long a1,
+ unsigned long a2, unsigned long a3,
+ unsigned long a4, unsigned long a5);
int HYPERVISOR_xen_version(int cmd, void *arg);
int HYPERVISOR_console_io(int cmd, int count, char *str);
int HYPERVISOR_grant_table_op(unsigned int cmd, void *uop, unsigned int count);
@@ -88,4 +88,4 @@ MULTI_mmu_update(struct multicall_entry *mcl, struct mmu_update *req,
BUG();
}

-#endif /* _ASM_ARM_XEN_HYPERCALL_H */
+#endif /* _ARM_XEN_HYPERCALL_H */
--
2.24.0