[S390] Make user-copy operations run-time configurable.

Introduces a struct uaccess_ops which allows setting user-copy
operations at run-time.

Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 63 insertions, 195 deletions

diff --git a/include/asm-s390/futex.h b/include/asm-s390/futex.h
index ffedf14f89f6..5e261e1de671 100644
--- a/include/asm-s390/futex.h
+++ b/include/asm-s390/futex.h
@@ -7,75 +7,21 @@
 #include <asm/errno.h>
 #include <asm/uaccess.h>
 
-#ifndef __s390x__
-#define __futex_atomic_fixup \
-                     ".section __ex_table,\"a\"\n"                      \
-                     "   .align 4\n"                                    \
-                     "   .long  0b,4b,2b,4b,3b,4b\n"                    \
-                     ".previous"
-#else /* __s390x__ */
-#define __futex_atomic_fixup \
-                     ".section __ex_table,\"a\"\n"                      \
-                     "   .align 8\n"                                    \
-                     "   .quad  0b,4b,2b,4b,3b,4b\n"                    \
-                     ".previous"
-#endif /* __s390x__ */
-
-#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg)      \
-        asm volatile("   sacf 256\n"                                    \
-                     "0: l   %1,0(%6)\n"                                \
-                     "1: " insn                                         \
-                     "2: cs  %1,%2,0(%6)\n"                             \
-                     "3: jl  1b\n"                                      \
-                     "   lhi %0,0\n"                                    \
-                     "4: sacf 0\n"                                      \
-                     __futex_atomic_fixup                               \
-                     : "=d" (ret), "=&d" (oldval), "=&d" (newval),      \
-                       "=m" (*uaddr)                                    \
-                     : "0" (-EFAULT), "d" (oparg), "a" (uaddr),         \
-                       "m" (*uaddr) : "cc" );
-
 static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
 {
         int op = (encoded_op >> 28) & 7;
         int cmp = (encoded_op >> 24) & 15;
         int oparg = (encoded_op << 8) >> 20;
         int cmparg = (encoded_op << 20) >> 20;
-        int oldval = 0, newval, ret;
+        int oldval, ret;
+
         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
                 oparg = 1 << oparg;
 
         if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
                 return -EFAULT;
 
-        inc_preempt_count();
-
-        switch (op) {
-        case FUTEX_OP_SET:
-                __futex_atomic_op("lr %2,%5\n",
-                                  ret, oldval, newval, uaddr, oparg);
-                break;
-        case FUTEX_OP_ADD:
-                __futex_atomic_op("lr %2,%1\nar %2,%5\n",
-                                  ret, oldval, newval, uaddr, oparg);
-                break;
-        case FUTEX_OP_OR:
-                __futex_atomic_op("lr %2,%1\nor %2,%5\n",
-                                  ret, oldval, newval, uaddr, oparg);
-                break;
-        case FUTEX_OP_ANDN:
-                __futex_atomic_op("lr %2,%1\nnr %2,%5\n",
-                                  ret, oldval, newval, uaddr, oparg);
-                break;
-        case FUTEX_OP_XOR:
-                __futex_atomic_op("lr %2,%1\nxr %2,%5\n",
-                                  ret, oldval, newval, uaddr, oparg);
-                break;
-        default:
-                ret = -ENOSYS;
-        }
-
-        dec_preempt_count();
+        ret = uaccess.futex_atomic_op(op, uaddr, oparg, &oldval);
 
         if (!ret) {
                 switch (cmp) {
@@ -91,32 +37,13 @@ static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
         return ret;
 }
 
-static inline int
-futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
+static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr,
+                                                int oldval, int newval)
 {
-        int ret;
-
         if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
                 return -EFAULT;
-        asm volatile("   sacf 256\n"
-                     "   cs   %1,%4,0(%5)\n"
-                     "0: lr   %0,%1\n"
-                     "1: sacf 0\n"
-#ifndef __s390x__
-                     ".section __ex_table,\"a\"\n"
-                     "   .align 4\n"
-                     "   .long  0b,1b\n"
-                     ".previous"
-#else /* __s390x__ */
-                     ".section __ex_table,\"a\"\n"
-                     "   .align 8\n"
-                     "   .quad  0b,1b\n"
-                     ".previous"
-#endif /* __s390x__ */
-                     : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
-                     : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
-                     : "cc", "memory" );
-        return oldval;
+
+        return uaccess.futex_atomic_cmpxchg(uaddr, oldval, newval);
 }
 
 #endif /* __KERNEL__ */
diff --git a/include/asm-s390/uaccess.h b/include/asm-s390/uaccess.h
index 0b7c0ca4c3d7..39a2716ae188 100644
--- a/include/asm-s390/uaccess.h
+++ b/include/asm-s390/uaccess.h
@@ -47,7 +47,7 @@
                 S390_lowcore.user_asce : S390_lowcore.kernel_asce;      \
         asm volatile ("lctlg 7,7,%0" : : "m" (__pto) );                 \
 })
-#else
+#else /* __s390x__ */
 #define set_fs(x) \
 ({                                                                      \
         unsigned long __pto;                                            \
@@ -56,7 +56,7 @@
                 S390_lowcore.user_asce : S390_lowcore.kernel_asce;      \
         asm volatile ("lctl  7,7,%0" : : "m" (__pto) );                 \
 })
-#endif
+#endif /* __s390x__ */
 
 #define segment_eq(a,b) ((a).ar4 == (b).ar4)
 
@@ -85,76 +85,50 @@ struct exception_table_entry
         unsigned long insn, fixup;
 };
 
-#ifndef __s390x__
-#define __uaccess_fixup \
-        ".section .fixup,\"ax\"\n"      \
-        "2: lhi    %0,%4\n"             \
-        "   bras   1,3f\n"              \
-        "   .long  1b\n"                \
-        "3: l      1,0(1)\n"            \
-        "   br     1\n"                 \
-        ".previous\n"                   \
-        ".section __ex_table,\"a\"\n"   \
-        "   .align 4\n"                 \
-        "   .long  0b,2b\n"             \
-        ".previous"
-#define __uaccess_clobber "cc", "1"
-#else /* __s390x__ */
-#define __uaccess_fixup \
-        ".section .fixup,\"ax\"\n"      \
-        "2: lghi   %0,%4\n"             \
-        "   jg     1b\n"                \
-        ".previous\n"                   \
-        ".section __ex_table,\"a\"\n"   \
-        "   .align 8\n"                 \
-        "   .quad  0b,2b\n"             \
-        ".previous"
-#define __uaccess_clobber "cc"
-#endif /* __s390x__ */
+struct uaccess_ops {
+        size_t (*copy_from_user)(size_t, const void __user *, void *);
+        size_t (*copy_from_user_small)(size_t, const void __user *, void *);
+        size_t (*copy_to_user)(size_t, void __user *, const void *);
+        size_t (*copy_to_user_small)(size_t, void __user *, const void *);
+        size_t (*copy_in_user)(size_t, void __user *, const void __user *);
+        size_t (*clear_user)(size_t, void __user *);
+        size_t (*strnlen_user)(size_t, const char __user *);
+        size_t (*strncpy_from_user)(size_t, const char __user *, char *);
+        int (*futex_atomic_op)(int op, int __user *, int oparg, int *old);
+        int (*futex_atomic_cmpxchg)(int __user *, int old, int new);
+};
+
+extern struct uaccess_ops uaccess;
+extern struct uaccess_ops uaccess_std;
+
+static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
+{
+        size = uaccess.copy_to_user_small(size, ptr, x);
+        return size ? -EFAULT : size;
+}
+
+static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
+{
+        size = uaccess.copy_from_user_small(size, ptr, x);
+        return size ? -EFAULT : size;
+}
 
 /*
  * These are the main single-value transfer routines.  They automatically
  * use the right size if we just have the right pointer type.
  */
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
-#define __put_user_asm(x, ptr, err) \
-({                                                              \
-        err = 0;                                                \
-        asm volatile(                                           \
-                "0: mvcs  0(%1,%2),%3,%0\n"                     \
-                "1:\n"                                          \
-                __uaccess_fixup                                 \
-                : "+&d" (err)                                   \
-                : "d" (sizeof(*(ptr))), "a" (ptr), "Q" (x),     \
-                  "K" (-EFAULT)                                 \
-                : __uaccess_clobber );                          \
-})
-#else
-#define __put_user_asm(x, ptr, err) \
-({                                                              \
-        err = 0;                                                \
-        asm volatile(                                           \
-                "0: mvcs  0(%1,%2),0(%3),%0\n"                  \
-                "1:\n"                                          \
-                __uaccess_fixup                                 \
-                : "+&d" (err)                                   \
-                : "d" (sizeof(*(ptr))), "a" (ptr), "a" (&(x)),  \
-                  "K" (-EFAULT), "m" (x)                        \
-                : __uaccess_clobber );                          \
-})
-#endif
-
 #define __put_user(x, ptr) \
 ({                                                              \
         __typeof__(*(ptr)) __x = (x);                           \
-        int __pu_err;                                           \
+        int __pu_err = -EFAULT;                                 \
         __chk_user_ptr(ptr);                                    \
         switch (sizeof (*(ptr))) {                              \
         case 1:                                                 \
         case 2:                                                 \
         case 4:                                                 \
         case 8:                                                 \
-                __put_user_asm(__x, ptr, __pu_err);             \
+                __pu_err = __put_user_fn(sizeof (*(ptr)),       \
+                                         ptr, &__x);            \
                 break;                                          \
         default:                                                \
                 __put_user_bad();                               \
@@ -172,60 +146,36 @@ struct exception_table_entry
 
 extern int __put_user_bad(void) __attribute__((noreturn));
 
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
-#define __get_user_asm(x, ptr, err) \
-({                                                              \
-        err = 0;                                                \
-        asm volatile (                                          \
-                "0: mvcp  %O1(%2,%R1),0(%3),%0\n"               \
-                "1:\n"                                          \
-                __uaccess_fixup                                 \
-                : "+&d" (err), "=Q" (x)                         \
-                : "d" (sizeof(*(ptr))), "a" (ptr),              \
-                  "K" (-EFAULT)                                 \
-                : __uaccess_clobber );                          \
-})
-#else
-#define __get_user_asm(x, ptr, err) \
-({                                                              \
-        err = 0;                                                \
-        asm volatile (                                          \
-                "0: mvcp  0(%2,%5),0(%3),%0\n"                  \
-                "1:\n"                                          \
-                __uaccess_fixup                                 \
-                : "+&d" (err), "=m" (x)                         \
-                : "d" (sizeof(*(ptr))), "a" (ptr),              \
-                  "K" (-EFAULT), "a" (&(x))                     \
-                : __uaccess_clobber );                          \
-})
-#endif
-
 #define __get_user(x, ptr)                                      \
 ({                                                              \
-        int __gu_err;                                           \
-        __chk_user_ptr(ptr);                                    \
+        int __gu_err = -EFAULT;                                 \
+        __chk_user_ptr(ptr);                                    \
         switch (sizeof(*(ptr))) {                               \
         case 1: {                                               \
                 unsigned char __x;                              \
-                __get_user_asm(__x, ptr, __gu_err);             \
+                __gu_err = __get_user_fn(sizeof (*(ptr)),       \
+                                         ptr, &__x);            \
                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
                 break;                                          \
         };                                                      \
         case 2: {                                               \
                 unsigned short __x;                             \
-                __get_user_asm(__x, ptr, __gu_err);             \
+                __gu_err = __get_user_fn(sizeof (*(ptr)),       \
+                                         ptr, &__x);            \
                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
                 break;                                          \
         };                                                      \
         case 4: {                                               \
                 unsigned int __x;                               \
-                __get_user_asm(__x, ptr, __gu_err);             \
+                __gu_err = __get_user_fn(sizeof (*(ptr)),       \
+                                         ptr, &__x);            \
                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
                 break;                                          \
         };                                                      \
         case 8: {                                               \
                 unsigned long long __x;                         \
-                __get_user_asm(__x, ptr, __gu_err);             \
+                __gu_err = __get_user_fn(sizeof (*(ptr)),       \
+                                         ptr, &__x);            \
                 (x) = *(__force __typeof__(*(ptr)) *) &__x;     \
                 break;                                          \
         };                                                      \
@@ -247,8 +197,6 @@ extern int __get_user_bad(void) __attribute__((noreturn));
 #define __put_user_unaligned __put_user
 #define __get_user_unaligned __get_user
 
-extern long __copy_to_user_asm(const void *from, long n, void __user *to);
-
 /**
  * __copy_to_user: - Copy a block of data into user space, with less checking.
  * @to:   Destination address, in user space.
@@ -266,7 +214,10 @@ extern long __copy_to_user_asm(const void *from, long n, void __user *to);
 static inline unsigned long
 __copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-        return __copy_to_user_asm(from, n, to);
+        if (__builtin_constant_p(n) && (n <= 256))
+                return uaccess.copy_to_user_small(n, to, from);
+        else
+                return uaccess.copy_to_user(n, to, from);
 }
 
 #define __copy_to_user_inatomic __copy_to_user
@@ -294,8 +245,6 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
         return n;
 }
 
-extern long __copy_from_user_asm(void *to, long n, const void __user *from);
-
 /**
  * __copy_from_user: - Copy a block of data from user space, with less checking.
  * @to:   Destination address, in kernel space.
@@ -316,7 +265,10 @@ extern long __copy_from_user_asm(void *to, long n, const void __user *from);
 static inline unsigned long
 __copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-        return __copy_from_user_asm(to, n, from);
+        if (__builtin_constant_p(n) && (n <= 256))
+                return uaccess.copy_from_user_small(n, from, to);
+        else
+                return uaccess.copy_from_user(n, from, to);
 }
 
 /**
@@ -346,13 +298,10 @@ copy_from_user(void *to, const void __user *from, unsigned long n)
         return n;
 }
 
-extern unsigned long __copy_in_user_asm(const void __user *from, long n,
-                                                        void __user *to);
-
 static inline unsigned long
 __copy_in_user(void __user *to, const void __user *from, unsigned long n)
 {
-        return __copy_in_user_asm(from, n, to);
+        return uaccess.copy_in_user(n, to, from);
 }
 
 static inline unsigned long
@@ -360,34 +309,28 @@ copy_in_user(void __user *to, const void __user *from, unsigned long n)
 {
         might_sleep();
         if (__access_ok(from,n) && __access_ok(to,n))
-                n = __copy_in_user_asm(from, n, to);
+                n = __copy_in_user(to, from, n);
         return n;
 }
 
 /*
  * Copy a null terminated string from userspace.
  */
-extern long __strncpy_from_user_asm(long count, char *dst,
-                                        const char __user *src);
-
 static inline long
 strncpy_from_user(char *dst, const char __user *src, long count)
 {
         long res = -EFAULT;
         might_sleep();
         if (access_ok(VERIFY_READ, src, 1))
-                res = __strncpy_from_user_asm(count, dst, src);
+                res = uaccess.strncpy_from_user(count, src, dst);
         return res;
 }
 
-
-extern long __strnlen_user_asm(long count, const char __user *src);
-
 static inline unsigned long
 strnlen_user(const char __user * src, unsigned long n)
 {
         might_sleep();
-        return __strnlen_user_asm(n, src);
+        return uaccess.strnlen_user(n, src);
 }
 
 /**
@@ -410,12 +353,10 @@ strnlen_user(const char __user * src, unsigned long n)
  * Zero Userspace
  */
 
-extern long __clear_user_asm(void __user *to, long n);
-
 static inline unsigned long
 __clear_user(void __user *to, unsigned long n)
 {
-        return __clear_user_asm(to, n);
+        return uaccess.clear_user(n, to);
 }
 
 static inline unsigned long
@@ -423,7 +364,7 @@ clear_user(void __user *to, unsigned long n)
 {
         might_sleep();
         if (access_ok(VERIFY_WRITE, to, n))
-                n = __clear_user_asm(to, n);
+                n = uaccess.clear_user(n, to);
         return n;
 }