s390: split TIF bits into CIF, PIF and TIF bits

The oi and ni instructions used in entry[64].S to set and clear bits
in the thread-flags are not guaranteed to be atomic in regard to other
CPUs. Split the TIF bits into CPU, pt_regs and thread-info specific
bits. Updates on the TIF bits are done with atomic instructions,
updates on CPU and pt_regs bits are done with non-atomic instructions.

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

arch/s390/include/asm/lowcore.h

@@ -93,7 +93,9 @@ struct _lowcore {
 	__u32	save_area_sync[8];		/* 0x0200 */
 	__u32	save_area_async[8];		/* 0x0220 */
 	__u32	save_area_restart[1];		/* 0x0240 */
-	__u8	pad_0x0244[0x0248-0x0244];	/* 0x0244 */
+
+	/* CPU flags. */
+	__u32	cpu_flags;			/* 0x0244 */
 
 	/* Return psws. */
 	psw_t	return_psw;			/* 0x0248 */
@@ -237,7 +239,9 @@ struct _lowcore {
 	__u64	save_area_sync[8];		/* 0x0200 */
 	__u64	save_area_async[8];		/* 0x0240 */
 	__u64	save_area_restart[1];		/* 0x0280 */
-	__u8	pad_0x0288[0x0290-0x0288];	/* 0x0288 */
+
+	/* CPU flags. */
+	__u64	cpu_flags;			/* 0x0288 */
 
 	/* Return psws. */
 	psw_t	return_psw;			/* 0x0290 */

arch/s390/include/asm/mmu_context.h

@@ -36,7 +36,7 @@ static inline void set_user_asce(struct mm_struct *mm)
 
 	S390_lowcore.user_asce = mm->context.asce_bits | __pa(pgd);
 	set_fs(current->thread.mm_segment);
-	set_thread_flag(TIF_ASCE);
+	set_cpu_flag(CIF_ASCE);
 }
 
 static inline void clear_user_asce(void)
@@ -54,7 +54,7 @@ static inline void load_kernel_asce(void)
 	__ctl_store(asce, 1, 1);
 	if (asce != S390_lowcore.kernel_asce)
 		__ctl_load(S390_lowcore.kernel_asce, 1, 1);
-	set_thread_flag(TIF_ASCE);
+	set_cpu_flag(CIF_ASCE);
 }
 
 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
@@ -70,7 +70,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
 	__ctl_load(S390_lowcore.kernel_asce, 1, 1);
 	__ctl_load(S390_lowcore.kernel_asce, 7, 7);
 	/* Delay loading of the new ASCE to control registers CR1 & CR7 */
-	set_thread_flag(TIF_ASCE);
+	set_cpu_flag(CIF_ASCE);
 	atomic_inc(&next->context.attach_count);
 	atomic_dec(&prev->context.attach_count);
 	if (MACHINE_HAS_TLB_LC)

arch/s390/include/asm/processor.h

@@ -11,6 +11,13 @@
 #ifndef __ASM_S390_PROCESSOR_H
 #define __ASM_S390_PROCESSOR_H
 
+#define CIF_MCCK_PENDING	0	/* machine check handling is pending */
+#define CIF_ASCE		1	/* user asce needs fixup / uaccess */
+
+#define _CIF_MCCK_PENDING	(1<<CIF_MCCK_PENDING)
+#define _CIF_ASCE		(1<<CIF_ASCE)
+
+
 #ifndef __ASSEMBLY__
 
 #include <linux/linkage.h>
@@ -21,6 +28,21 @@
 #include <asm/setup.h>
 #include <asm/runtime_instr.h>
 
+static inline void set_cpu_flag(int flag)
+{
+	S390_lowcore.cpu_flags |= (1U << flag);
+}
+
+static inline void clear_cpu_flag(int flag)
+{
+	S390_lowcore.cpu_flags &= ~(1U << flag);
+}
+
+static inline int test_cpu_flag(int flag)
+{
+	return !!(S390_lowcore.cpu_flags & (1U << flag));
+}
+
 /*
  * Default implementation of macro that returns current
  * instruction pointer ("program counter").

arch/s390/include/asm/ptrace.h

@@ -8,6 +8,12 @@
 
 #include <uapi/asm/ptrace.h>
 
+#define PIF_SYSCALL		0	/* inside a system call */
+#define PIF_PER_TRAP		1	/* deliver sigtrap on return to user */
+
+#define _PIF_SYSCALL		(1<<PIF_SYSCALL)
+#define _PIF_PER_TRAP		(1<<PIF_PER_TRAP)
+
 #ifndef __ASSEMBLY__
 
 #define PSW_KERNEL_BITS	(PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_ASC_HOME | \
@@ -29,6 +35,7 @@ struct pt_regs
 	unsigned int int_code;
 	unsigned int int_parm;
 	unsigned long int_parm_long;
+	unsigned long flags;
 };
 
 /*
@@ -79,6 +86,21 @@ struct per_struct_kernel {
 #define PER_CONTROL_SUSPENSION		0x00400000UL
 #define PER_CONTROL_ALTERATION		0x00200000UL
 
+static inline void set_pt_regs_flag(struct pt_regs *regs, int flag)
+{
+	regs->flags |= (1U << flag);
+}
+
+static inline void clear_pt_regs_flag(struct pt_regs *regs, int flag)
+{
+	regs->flags &= ~(1U << flag);
+}
+
+static inline int test_pt_regs_flag(struct pt_regs *regs, int flag)
+{
+	return !!(regs->flags & (1U << flag));
+}
+
 /*
  * These are defined as per linux/ptrace.h, which see.
  */

arch/s390/include/asm/syscall.h

@@ -28,7 +28,7 @@ extern const unsigned int sys_call_table_emu[];
 static inline long syscall_get_nr(struct task_struct *task,
 				  struct pt_regs *regs)
 {
-	return test_tsk_thread_flag(task, TIF_SYSCALL) ?
+	return test_pt_regs_flag(regs, PIF_SYSCALL) ?
 		(regs->int_code & 0xffff) : -1;
 }
 

arch/s390/include/asm/thread_info.h

@@ -77,30 +77,22 @@ static inline struct thread_info *current_thread_info(void)
 /*
  * thread information flags bit numbers
  */
-#define TIF_SYSCALL		0	/* inside a system call */
-#define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
-#define TIF_SIGPENDING		2	/* signal pending */
-#define TIF_NEED_RESCHED	3	/* rescheduling necessary */
-#define TIF_ASCE		5	/* user asce needs fixup / uaccess */
-#define TIF_PER_TRAP		6	/* deliver sigtrap on return to user */
-#define TIF_MCCK_PENDING	7	/* machine check handling is pending */
-#define TIF_SYSCALL_TRACE	8	/* syscall trace active */
-#define TIF_SYSCALL_AUDIT	9	/* syscall auditing active */
-#define TIF_SECCOMP		10	/* secure computing */
-#define TIF_SYSCALL_TRACEPOINT	11	/* syscall tracepoint instrumentation */
-#define TIF_31BIT		17	/* 32bit process */
-#define TIF_MEMDIE		18	/* is terminating due to OOM killer */
-#define TIF_RESTORE_SIGMASK	19	/* restore signal mask in do_signal() */
-#define TIF_SINGLE_STEP		20	/* This task is single stepped */
-#define TIF_BLOCK_STEP		21	/* This task is block stepped */
+#define TIF_NOTIFY_RESUME	0	/* callback before returning to user */
+#define TIF_SIGPENDING		1	/* signal pending */
+#define TIF_NEED_RESCHED	2	/* rescheduling necessary */
+#define TIF_SYSCALL_TRACE	3	/* syscall trace active */
+#define TIF_SYSCALL_AUDIT	4	/* syscall auditing active */
+#define TIF_SECCOMP		5	/* secure computing */
+#define TIF_SYSCALL_TRACEPOINT	6	/* syscall tracepoint instrumentation */
+#define TIF_31BIT		16	/* 32bit process */
+#define TIF_MEMDIE		17	/* is terminating due to OOM killer */
+#define TIF_RESTORE_SIGMASK	18	/* restore signal mask in do_signal() */
+#define TIF_SINGLE_STEP		19	/* This task is single stepped */
+#define TIF_BLOCK_STEP		20	/* This task is block stepped */
 
-#define _TIF_SYSCALL		(1<<TIF_SYSCALL)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
-#define _TIF_ASCE		(1<<TIF_ASCE)
-#define _TIF_PER_TRAP		(1<<TIF_PER_TRAP)
-#define _TIF_MCCK_PENDING	(1<<TIF_MCCK_PENDING)
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_SYSCALL_AUDIT	(1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP		(1<<TIF_SECCOMP)

arch/s390/kernel/asm-offsets.c

@@ -50,6 +50,7 @@ int main(void)
 	DEFINE(__PT_INT_CODE, offsetof(struct pt_regs, int_code));
 	DEFINE(__PT_INT_PARM, offsetof(struct pt_regs, int_parm));
 	DEFINE(__PT_INT_PARM_LONG, offsetof(struct pt_regs, int_parm_long));
+	DEFINE(__PT_FLAGS, offsetof(struct pt_regs, flags));
 	DEFINE(__PT_SIZE, sizeof(struct pt_regs));
 	BLANK();
 	DEFINE(__SF_BACKCHAIN, offsetof(struct stack_frame, back_chain));
@@ -115,6 +116,7 @@ int main(void)
 	DEFINE(__LC_SAVE_AREA_SYNC, offsetof(struct _lowcore, save_area_sync));
 	DEFINE(__LC_SAVE_AREA_ASYNC, offsetof(struct _lowcore, save_area_async));
 	DEFINE(__LC_SAVE_AREA_RESTART, offsetof(struct _lowcore, save_area_restart));
+	DEFINE(__LC_CPU_FLAGS, offsetof(struct _lowcore, cpu_flags));
 	DEFINE(__LC_RETURN_PSW, offsetof(struct _lowcore, return_psw));
 	DEFINE(__LC_RETURN_MCCK_PSW, offsetof(struct _lowcore, return_mcck_psw));
 	DEFINE(__LC_SYNC_ENTER_TIMER, offsetof(struct _lowcore, sync_enter_timer));

arch/s390/kernel/compat_signal.c

@@ -213,7 +213,7 @@ static int restore_sigregs32(struct pt_regs *regs,_sigregs32 __user *sregs)
 	       sizeof(current->thread.fp_regs));
 
 	restore_fp_regs(current->thread.fp_regs.fprs);
-	clear_thread_flag(TIF_SYSCALL);	/* No longer in a system call */
+	clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
 	return 0;
 }