MIPS: uaccess: Take EVA into account in [__]clear_user

commit d6a428fb583738ad685c91a684748cdee7b2a05f upstream.

__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@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10844/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
[james.hogan@imgtec.com: backport]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index 81d4d7e012ca5f1140413ce9f1f25b7f1357eae4..681331257bacc22276269cfccd4732da25fa1ab1 100644 (file)
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -1204,16 +1204,28 @@ __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 (config_enabled(CONFIG_EVA) && segment_eq(get_fs(), get_ds())) {
+               __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 1b2452e2be675b3cea0a3f27fa33e4458bb75fd3..c1e152a27b175c906fe67b61dbbd3bea2e6e14dc 100644 (file)
--- 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);
@@ -66,6 +67,7 @@ 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 7b0e5462ca517ac2c8411ef35d06f35b7867d73d..fd83406ceccc30c24c28febc673b6720e5907738 100644 (file)
--- a/arch/mips/lib/memset.S
+++ b/arch/mips/lib/memset.S
@@ -238,6 +238,8 @@ LEAF(memset)
 1:
 #ifndef CONFIG_EVA
 FEXPORT(__bzero)
+#else
+FEXPORT(__bzero_kernel)
 #endif
        __BUILD_BZERO LEGACY_MODE