__clear_user() (and clear_user() which uses it), always access the user
mode address space, which results in EVA store instructions when EVA is
enabled even if the current user address limit is KERNEL_DS.
Fix this by adding a new symbol __bzero_kernel for the normal kernel
address space bzero in EVA mode, and call that from __clear_user() if
eva_kernel_access().
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Markos Chandras <markos.chandras@xxxxxxxxxx>
Cc: Paul Burton <paul.burton@xxxxxxxxxx>
Cc: Leonid Yegoshin <leonid.yegoshin@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
---
I've not Cc'd stable on this patch as eva_kernel_access() was only added
in 4.2. I'll submit a backport once it is merged.
---
arch/mips/include/asm/uaccess.h | 32 ++++++++++++++++++++++----------
arch/mips/kernel/mips_ksyms.c | 2 ++
arch/mips/lib/memset.S | 2 ++
3 files changed, 26 insertions(+), 10 deletions(-)
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index 5014e187df23..2e3b3991cf0b 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -1235,16 +1235,28 @@ __clear_user(void __user *addr, __kernel_size_t size)
{
__kernel_size_t res;
- might_fault();
- __asm__ __volatile__(
- "move\t$4, %1\n\t"
- "move\t$5, $0\n\t"
- "move\t$6, %2\n\t"
- __MODULE_JAL(__bzero)
- "move\t%0, $6"
- : "=r" (res)
- : "r" (addr), "r" (size)
- : "$4", "$5", "$6", __UA_t0, __UA_t1, "$31");
+ if (eva_kernel_access()) {
+ __asm__ __volatile__(
+ "move\t$4, %1\n\t"
+ "move\t$5, $0\n\t"
+ "move\t$6, %2\n\t"
+ __MODULE_JAL(__bzero_kernel)
+ "move\t%0, $6"
+ : "=r" (res)
+ : "r" (addr), "r" (size)
+ : "$4", "$5", "$6", __UA_t0, __UA_t1, "$31");
+ } else {
+ might_fault();
+ __asm__ __volatile__(
+ "move\t$4, %1\n\t"
+ "move\t$5, $0\n\t"
+ "move\t$6, %2\n\t"
+ __MODULE_JAL(__bzero)
+ "move\t%0, $6"
+ : "=r" (res)
+ : "r" (addr), "r" (size)
+ : "$4", "$5", "$6", __UA_t0, __UA_t1, "$31");
+ }
return res;
}
diff --git a/arch/mips/kernel/mips_ksyms.c b/arch/mips/kernel/mips_ksyms.c
index 291af0b5c482..e2b6ab74643d 100644
--- a/arch/mips/kernel/mips_ksyms.c
+++ b/arch/mips/kernel/mips_ksyms.c
@@ -17,6 +17,7 @@
#include <asm/fpu.h>
#include <asm/msa.h>
+extern void *__bzero_kernel(void *__s, size_t __count);
extern void *__bzero(void *__s, size_t __count);
extern long __strncpy_from_kernel_nocheck_asm(char *__to,
const char *__from, long __len);
@@ -64,6 +65,7 @@ EXPORT_SYMBOL(__copy_from_user_eva);
EXPORT_SYMBOL(__copy_in_user_eva);
EXPORT_SYMBOL(__copy_to_user_eva);
EXPORT_SYMBOL(__copy_user_inatomic_eva);
+EXPORT_SYMBOL(__bzero_kernel);
#endif
EXPORT_SYMBOL(__bzero);
EXPORT_SYMBOL(__strncpy_from_kernel_nocheck_asm);
diff --git a/arch/mips/lib/memset.S b/arch/mips/lib/memset.S
index b8e63fd00375..8f0019a2e5c8 100644
--- a/arch/mips/lib/memset.S
+++ b/arch/mips/lib/memset.S
@@ -283,6 +283,8 @@ LEAF(memset)
1:
#ifndef CONFIG_EVA
FEXPORT(__bzero)
+#else
+FEXPORT(__bzero_kernel)
#endif
__BUILD_BZERO LEGACY_MODE
--
2.3.6
