Merge branch 'cmpxchg_user_key' into features

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/include/asm/asm-extable.h

@@ -12,6 +12,7 @@
 #define EX_TYPE_UA_STORE	3
 #define EX_TYPE_UA_LOAD_MEM	4
 #define EX_TYPE_UA_LOAD_REG	5
+#define EX_TYPE_UA_LOAD_REGPAIR	6
 
 #define EX_DATA_REG_ERR_SHIFT	0
 #define EX_DATA_REG_ERR		GENMASK(3, 0)
@@ -85,4 +86,7 @@
 #define EX_TABLE_UA_LOAD_REG(_fault, _target, _regerr, _regzero)	\
 	__EX_TABLE_UA(__ex_table, _fault, _target, EX_TYPE_UA_LOAD_REG, _regerr, _regzero, 0)
 
+#define EX_TABLE_UA_LOAD_REGPAIR(_fault, _target, _regerr, _regzero)	\
+	__EX_TABLE_UA(__ex_table, _fault, _target, EX_TYPE_UA_LOAD_REGPAIR, _regerr, _regzero, 0)
+
 #endif /* __ASM_EXTABLE_H */

arch/s390/include/asm/cmpxchg.h

@@ -88,67 +88,90 @@ static __always_inline unsigned long __cmpxchg(unsigned long address,
 					       unsigned long old,
 					       unsigned long new, int size)
 {
-	unsigned long prev, tmp;
-	int shift;
-
 	switch (size) {
-	case 1:
+	case 1: {
+		unsigned int prev, shift, mask;
+
 		shift = (3 ^ (address & 3)) << 3;
 		address ^= address & 3;
+		old = (old & 0xff) << shift;
+		new = (new & 0xff) << shift;
+		mask = ~(0xff << shift);
 		asm volatile(
-			"       l       %0,%2\n"
-			"0:     nr      %0,%5\n"
-			"       lr      %1,%0\n"
-			"       or      %0,%3\n"
-			"       or      %1,%4\n"
-			"       cs      %0,%1,%2\n"
-			"       jnl     1f\n"
-			"       xr      %1,%0\n"
-			"       nr      %1,%5\n"
-			"       jnz     0b\n"
+			"	l	%[prev],%[address]\n"
+			"	nr	%[prev],%[mask]\n"
+			"	xilf	%[mask],0xffffffff\n"
+			"	or	%[new],%[prev]\n"
+			"	or	%[prev],%[tmp]\n"
+			"0:	lr	%[tmp],%[prev]\n"
+			"	cs	%[prev],%[new],%[address]\n"
+			"	jnl	1f\n"
+			"	xr	%[tmp],%[prev]\n"
+			"	xr	%[new],%[tmp]\n"
+			"	nr	%[tmp],%[mask]\n"
+			"	jz	0b\n"
 			"1:"
-			: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) address)
-			: "d" ((old & 0xff) << shift),
-			  "d" ((new & 0xff) << shift),
-			  "d" (~(0xff << shift))
-			: "memory", "cc");
+			: [prev] "=&d" (prev),
+			  [address] "+Q" (*(int *)address),
+			  [tmp] "+&d" (old),
+			  [new] "+&d" (new),
+			  [mask] "+&d" (mask)
+			:: "memory", "cc");
 		return prev >> shift;
-	case 2:
+	}
+	case 2: {
+		unsigned int prev, shift, mask;
+
 		shift = (2 ^ (address & 2)) << 3;
 		address ^= address & 2;
+		old = (old & 0xffff) << shift;
+		new = (new & 0xffff) << shift;
+		mask = ~(0xffff << shift);
 		asm volatile(
-			"       l       %0,%2\n"
-			"0:     nr      %0,%5\n"
-			"       lr      %1,%0\n"
-			"       or      %0,%3\n"
-			"       or      %1,%4\n"
-			"       cs      %0,%1,%2\n"
-			"       jnl     1f\n"
-			"       xr      %1,%0\n"
-			"       nr      %1,%5\n"
-			"       jnz     0b\n"
+			"	l	%[prev],%[address]\n"
+			"	nr	%[prev],%[mask]\n"
+			"	xilf	%[mask],0xffffffff\n"
+			"	or	%[new],%[prev]\n"
+			"	or	%[prev],%[tmp]\n"
+			"0:	lr	%[tmp],%[prev]\n"
+			"	cs	%[prev],%[new],%[address]\n"
+			"	jnl	1f\n"
+			"	xr	%[tmp],%[prev]\n"
+			"	xr	%[new],%[tmp]\n"
+			"	nr	%[tmp],%[mask]\n"
+			"	jz	0b\n"
 			"1:"
-			: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) address)
-			: "d" ((old & 0xffff) << shift),
-			  "d" ((new & 0xffff) << shift),
-			  "d" (~(0xffff << shift))
-			: "memory", "cc");
+			: [prev] "=&d" (prev),
+			  [address] "+Q" (*(int *)address),
+			  [tmp] "+&d" (old),
+			  [new] "+&d" (new),
+			  [mask] "+&d" (mask)
+			:: "memory", "cc");
 		return prev >> shift;
-	case 4:
+	}
+	case 4: {
+		unsigned int prev = old;
+
 		asm volatile(
-			"       cs      %0,%3,%1\n"
-			: "=&d" (prev), "+Q" (*(int *) address)
-			: "0" (old), "d" (new)
+			"	cs	%[prev],%[new],%[address]\n"
+			: [prev] "+&d" (prev),
+			  [address] "+Q" (*(int *)address)
+			: [new] "d" (new)
 			: "memory", "cc");
 		return prev;
-	case 8:
+	}
+	case 8: {
+		unsigned long prev = old;
+
 		asm volatile(
-			"       csg     %0,%3,%1\n"
-			: "=&d" (prev), "+QS" (*(long *) address)
-			: "0" (old), "d" (new)
+			"	csg	%[prev],%[new],%[address]\n"
+			: [prev] "+&d" (prev),
+			  [address] "+QS" (*(long *)address)
+			: [new] "d" (new)
 			: "memory", "cc");
 		return prev;
 	}
+	}
 	__cmpxchg_called_with_bad_pointer();
 	return old;
 }

arch/s390/include/asm/uaccess.h

@@ -390,4 +390,212 @@ do {									\
 		goto err_label;						\
 } while (0)
 
+void __cmpxchg_user_key_called_with_bad_pointer(void);
+
+#define CMPXCHG_USER_KEY_MAX_LOOPS 128
+
+static __always_inline int __cmpxchg_user_key(unsigned long address, void *uval,
+					      __uint128_t old, __uint128_t new,
+					      unsigned long key, int size)
+{
+	int rc = 0;
+
+	switch (size) {
+	case 1: {
+		unsigned int prev, shift, mask, _old, _new;
+		unsigned long count;
+
+		shift = (3 ^ (address & 3)) << 3;
+		address ^= address & 3;
+		_old = ((unsigned int)old & 0xff) << shift;
+		_new = ((unsigned int)new & 0xff) << shift;
+		mask = ~(0xff << shift);
+		asm volatile(
+			"	spka	0(%[key])\n"
+			"	sacf	256\n"
+			"	llill	%[count],%[max_loops]\n"
+			"0:	l	%[prev],%[address]\n"
+			"1:	nr	%[prev],%[mask]\n"
+			"	xilf	%[mask],0xffffffff\n"
+			"	or	%[new],%[prev]\n"
+			"	or	%[prev],%[tmp]\n"
+			"2:	lr	%[tmp],%[prev]\n"
+			"3:	cs	%[prev],%[new],%[address]\n"
+			"4:	jnl	5f\n"
+			"	xr	%[tmp],%[prev]\n"
+			"	xr	%[new],%[tmp]\n"
+			"	nr	%[tmp],%[mask]\n"
+			"	jnz	5f\n"
+			"	brct	%[count],2b\n"
+			"5:	sacf	768\n"
+			"	spka	%[default_key]\n"
+			EX_TABLE_UA_LOAD_REG(0b, 5b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REG(1b, 5b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REG(3b, 5b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REG(4b, 5b, %[rc], %[prev])
+			: [rc] "+&d" (rc),
+			  [prev] "=&d" (prev),
+			  [address] "+Q" (*(int *)address),
+			  [tmp] "+&d" (_old),
+			  [new] "+&d" (_new),
+			  [mask] "+&d" (mask),
+			  [count] "=a" (count)
+			: [key] "%[count]" (key << 4),
+			  [default_key] "J" (PAGE_DEFAULT_KEY),
+			  [max_loops] "J" (CMPXCHG_USER_KEY_MAX_LOOPS)
+			: "memory", "cc");
+		*(unsigned char *)uval = prev >> shift;
+		if (!count)
+			rc = -EAGAIN;
+		return rc;
+	}
+	case 2: {
+		unsigned int prev, shift, mask, _old, _new;
+		unsigned long count;
+
+		shift = (2 ^ (address & 2)) << 3;
+		address ^= address & 2;
+		_old = ((unsigned int)old & 0xffff) << shift;
+		_new = ((unsigned int)new & 0xffff) << shift;
+		mask = ~(0xffff << shift);
+		asm volatile(
+			"	spka	0(%[key])\n"
+			"	sacf	256\n"
+			"	llill	%[count],%[max_loops]\n"
+			"0:	l	%[prev],%[address]\n"
+			"1:	nr	%[prev],%[mask]\n"
+			"	xilf	%[mask],0xffffffff\n"
+			"	or	%[new],%[prev]\n"
+			"	or	%[prev],%[tmp]\n"
+			"2:	lr	%[tmp],%[prev]\n"
+			"3:	cs	%[prev],%[new],%[address]\n"
+			"4:	jnl	5f\n"
+			"	xr	%[tmp],%[prev]\n"
+			"	xr	%[new],%[tmp]\n"
+			"	nr	%[tmp],%[mask]\n"
+			"	jnz	5f\n"
+			"	brct	%[count],2b\n"
+			"5:	sacf	768\n"
+			"	spka	%[default_key]\n"
+			EX_TABLE_UA_LOAD_REG(0b, 5b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REG(1b, 5b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REG(3b, 5b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REG(4b, 5b, %[rc], %[prev])
+			: [rc] "+&d" (rc),
+			  [prev] "=&d" (prev),
+			  [address] "+Q" (*(int *)address),
+			  [tmp] "+&d" (_old),
+			  [new] "+&d" (_new),
+			  [mask] "+&d" (mask),
+			  [count] "=a" (count)
+			: [key] "%[count]" (key << 4),
+			  [default_key] "J" (PAGE_DEFAULT_KEY),
+			  [max_loops] "J" (CMPXCHG_USER_KEY_MAX_LOOPS)
+			: "memory", "cc");
+		*(unsigned short *)uval = prev >> shift;
+		if (!count)
+			rc = -EAGAIN;
+		return rc;
+	}
+	case 4:	{
+		unsigned int prev = old;
+
+		asm volatile(
+			"	spka	0(%[key])\n"
+			"	sacf	256\n"
+			"0:	cs	%[prev],%[new],%[address]\n"
+			"1:	sacf	768\n"
+			"	spka	%[default_key]\n"
+			EX_TABLE_UA_LOAD_REG(0b, 1b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REG(1b, 1b, %[rc], %[prev])
+			: [rc] "+&d" (rc),
+			  [prev] "+&d" (prev),
+			  [address] "+Q" (*(int *)address)
+			: [new] "d" ((unsigned int)new),
+			  [key] "a" (key << 4),
+			  [default_key] "J" (PAGE_DEFAULT_KEY)
+			: "memory", "cc");
+		*(unsigned int *)uval = prev;
+		return rc;
+	}
+	case 8: {
+		unsigned long prev = old;
+
+		asm volatile(
+			"	spka	0(%[key])\n"
+			"	sacf	256\n"
+			"0:	csg	%[prev],%[new],%[address]\n"
+			"1:	sacf	768\n"
+			"	spka	%[default_key]\n"
+			EX_TABLE_UA_LOAD_REG(0b, 1b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REG(1b, 1b, %[rc], %[prev])
+			: [rc] "+&d" (rc),
+			  [prev] "+&d" (prev),
+			  [address] "+QS" (*(long *)address)
+			: [new] "d" ((unsigned long)new),
+			  [key] "a" (key << 4),
+			  [default_key] "J" (PAGE_DEFAULT_KEY)
+			: "memory", "cc");
+		*(unsigned long *)uval = prev;
+		return rc;
+	}
+	case 16: {
+		__uint128_t prev = old;
+
+		asm volatile(
+			"	spka	0(%[key])\n"
+			"	sacf	256\n"
+			"0:	cdsg	%[prev],%[new],%[address]\n"
+			"1:	sacf	768\n"
+			"	spka	%[default_key]\n"
+			EX_TABLE_UA_LOAD_REGPAIR(0b, 1b, %[rc], %[prev])
+			EX_TABLE_UA_LOAD_REGPAIR(1b, 1b, %[rc], %[prev])
+			: [rc] "+&d" (rc),
+			  [prev] "+&d" (prev),
+			  [address] "+QS" (*(__int128_t *)address)
+			: [new] "d" (new),
+			  [key] "a" (key << 4),
+			  [default_key] "J" (PAGE_DEFAULT_KEY)
+			: "memory", "cc");
+		*(__uint128_t *)uval = prev;
+		return rc;
+	}
+	}
+	__cmpxchg_user_key_called_with_bad_pointer();
+	return rc;
+}
+
+/**
+ * cmpxchg_user_key() - cmpxchg with user space target, honoring storage keys
+ * @ptr: User space address of value to compare to @old and exchange with
+ *	 @new. Must be aligned to sizeof(*@ptr).
+ * @uval: Address where the old value of *@ptr is written to.
+ * @old: Old value. Compared to the content pointed to by @ptr in order to
+ *	 determine if the exchange occurs. The old value read from *@ptr is
+ *	 written to *@uval.
+ * @new: New value to place at *@ptr.
+ * @key: Access key to use for checking storage key protection.
+ *
+ * Perform a cmpxchg on a user space target, honoring storage key protection.
+ * @key alone determines how key checking is performed, neither
+ * storage-protection-override nor fetch-protection-override apply.
+ * The caller must compare *@uval and @old to determine if values have been
+ * exchanged. In case of an exception *@uval is set to zero.
+ *
+ * Return:     0: cmpxchg executed
+ *	       -EFAULT: an exception happened when trying to access *@ptr
+ *	       -EAGAIN: maxed out number of retries (byte and short only)
+ */
+#define cmpxchg_user_key(ptr, uval, old, new, key)			\
+({									\
+	__typeof__(ptr) __ptr = (ptr);					\
+	__typeof__(uval) __uval = (uval);				\
+									\
+	BUILD_BUG_ON(sizeof(*(__ptr)) != sizeof(*(__uval)));		\
+	might_fault();							\
+	__chk_user_ptr(__ptr);						\
+	__cmpxchg_user_key((unsigned long)(__ptr), (void *)(__uval),	\
+			   (old), (new), (key), sizeof(*(__ptr)));	\
+})
+
 #endif /* __S390_UACCESS_H */

arch/s390/mm/extable.c

@@ -47,13 +47,16 @@ static bool ex_handler_ua_load_mem(const struct exception_table_entry *ex, struc
 	return true;
 }
 
-static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex, struct pt_regs *regs)
+static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex,
+				   bool pair, struct pt_regs *regs)
 {
 	unsigned int reg_zero = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
 	unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
 
 	regs->gprs[reg_err] = -EFAULT;
 	regs->gprs[reg_zero] = 0;
+	if (pair)
+		regs->gprs[reg_zero + 1] = 0;
 	regs->psw.addr = extable_fixup(ex);
 	return true;
 }
@@ -75,7 +78,9 @@ bool fixup_exception(struct pt_regs *regs)
 	case EX_TYPE_UA_LOAD_MEM:
 		return ex_handler_ua_load_mem(ex, regs);
 	case EX_TYPE_UA_LOAD_REG:
-		return ex_handler_ua_load_reg(ex, regs);
+		return ex_handler_ua_load_reg(ex, false, regs);
+	case EX_TYPE_UA_LOAD_REGPAIR:
+		return ex_handler_ua_load_reg(ex, true, regs);
 	}
 	panic("invalid exception table entry");
 }