s390: add support for transactional memory

Allow user-space processes to use transactional execution (TX).
If the TX facility is available user space programs can use
transactions for fine-grained serialization based on the data
objects that are referenced during a transaction. This is
useful for lockless data structures and speculative compiler
optimizations.

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

1 files changed, 69 insertions, 0 deletions

diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index e4be113fbac6..b817cc5e49ae 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -42,6 +42,7 @@ enum s390_regset {
 	REGSET_GENERAL,
 	REGSET_FP,
 	REGSET_LAST_BREAK,
+	REGSET_TDB,
 	REGSET_SYSTEM_CALL,
 	REGSET_GENERAL_EXTENDED,
 };
@@ -52,6 +53,21 @@ void update_per_regs(struct task_struct *task)
 	struct thread_struct *thread = &task->thread;
 	struct per_regs old, new;
 
+	/* Take care of the enable/disable of transactional execution. */
+	if (MACHINE_HAS_TE) {
+		unsigned long cr0, cr0_new;
+
+		__ctl_store(cr0, 0, 0);
+		/* set or clear transaction execution bits 8 and 9. */
+		if (task->thread.per_flags & PER_FLAG_NO_TE)
+			cr0_new = cr0 & ~(3UL << 54);
+		else
+			cr0_new = cr0 | (3UL << 54);
+		/* Only load control register 0 if necessary. */
+		if (cr0 != cr0_new)
+			__ctl_load(cr0_new, 0, 0);
+	}
+
 	/* Copy user specified PER registers */
 	new.control = thread->per_user.control;
 	new.start = thread->per_user.start;
@@ -60,6 +76,10 @@ void update_per_regs(struct task_struct *task)
 	/* merge TIF_SINGLE_STEP into user specified PER registers. */
 	if (test_tsk_thread_flag(task, TIF_SINGLE_STEP)) {
 		new.control |= PER_EVENT_IFETCH;
+#ifdef CONFIG_64BIT
+		new.control |= PER_CONTROL_SUSPENSION;
+		new.control |= PER_EVENT_TRANSACTION_END;
+#endif
 		new.start = 0;
 		new.end = PSW_ADDR_INSN;
 	}
@@ -100,6 +120,7 @@ void ptrace_disable(struct task_struct *task)
 	memset(&task->thread.per_event, 0, sizeof(task->thread.per_event));
 	clear_tsk_thread_flag(task, TIF_SINGLE_STEP);
 	clear_tsk_thread_flag(task, TIF_PER_TRAP);
+	task->thread.per_flags = 0;
 }
 
 #ifndef CONFIG_64BIT
@@ -416,6 +437,16 @@ long arch_ptrace(struct task_struct *child, long request,
 		put_user(task_thread_info(child)->last_break,
 			 (unsigned long __user *) data);
 		return 0;
+	case PTRACE_ENABLE_TE:
+		if (!MACHINE_HAS_TE)
+			return -EIO;
+		child->thread.per_flags &= ~PER_FLAG_NO_TE;
+		return 0;
+	case PTRACE_DISABLE_TE:
+		if (!MACHINE_HAS_TE)
+			return -EIO;
+		child->thread.per_flags |= PER_FLAG_NO_TE;
+		return 0;
 	default:
 		/* Removing high order bit from addr (only for 31 bit). */
 		addr &= PSW_ADDR_INSN;
@@ -903,6 +934,28 @@ static int s390_last_break_set(struct task_struct *target,
 	return 0;
 }
 
+static int s390_tdb_get(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			void *kbuf, void __user *ubuf)
+{
+	struct pt_regs *regs = task_pt_regs(target);
+	unsigned char *data;
+
+	if (!(regs->int_code & 0x200))
+		return -ENODATA;
+	data = target->thread.trap_tdb;
+	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, data, 0, 256);
+}
+
+static int s390_tdb_set(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			const void *kbuf, const void __user *ubuf)
+{
+	return 0;
+}
+
 #endif
 
 static int s390_system_call_get(struct task_struct *target,
@@ -951,6 +1004,14 @@ static const struct user_regset s390_regsets[] = {
 		.get = s390_last_break_get,
 		.set = s390_last_break_set,
 	},
+	[REGSET_TDB] = {
+		.core_note_type = NT_S390_TDB,
+		.n = 1,
+		.size = 256,
+		.align = 1,
+		.get = s390_tdb_get,
+		.set = s390_tdb_set,
+	},
 #endif
 	[REGSET_SYSTEM_CALL] = {
 		.core_note_type = NT_S390_SYSTEM_CALL,
@@ -1148,6 +1209,14 @@ static const struct user_regset s390_compat_regsets[] = {
 		.get = s390_compat_last_break_get,
 		.set = s390_compat_last_break_set,
 	},
+	[REGSET_TDB] = {
+		.core_note_type = NT_S390_TDB,
+		.n = 1,
+		.size = 256,
+		.align = 1,
+		.get = s390_tdb_get,
+		.set = s390_tdb_set,
+	},
 	[REGSET_SYSTEM_CALL] = {
 		.core_note_type = NT_S390_SYSTEM_CALL,
 		.n = 1,