[S390] ptrace cleanup

Overhaul program event recording and the code dealing with the ptrace
user space interface.

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

arch/s390/include/asm/processor.h

@@ -81,7 +81,8 @@ struct thread_struct {
 	mm_segment_t mm_segment;
         unsigned long prot_addr;        /* address of protection-excep.     */
         unsigned int trap_no;
-        per_struct per_info;
+	struct per_regs per_user;	/* User specified PER registers */
+	struct per_event per_event;	/* Cause of the last PER trap */
         /* pfault_wait is used to block the process on a pfault event */
 	unsigned long pfault_wait;
 };

arch/s390/include/asm/ptrace.h

@@ -331,10 +331,60 @@ struct pt_regs
 	unsigned short ilc;
 	unsigned short svcnr;
 };
+
+/*
+ * Program event recording (PER) register set.
+ */
+struct per_regs {
+	unsigned long control;		/* PER control bits */
+	unsigned long start;		/* PER starting address */
+	unsigned long end;		/* PER ending address */
+};
+
+/*
+ * PER event contains information about the cause of the last PER exception.
+ */
+struct per_event {
+	unsigned short cause;		/* PER code, ATMID and AI */
+	unsigned long address;		/* PER address */
+	unsigned char paid;		/* PER access identification */
+};
+
+/*
+ * Simplified per_info structure used to decode the ptrace user space ABI.
+ */
+struct per_struct_kernel {
+	unsigned long cr9;		/* PER control bits */
+	unsigned long cr10;		/* PER starting address */
+	unsigned long cr11;		/* PER ending address */
+	unsigned long bits;		/* Obsolete software bits */
+	unsigned long starting_addr;	/* User specified start address */
+	unsigned long ending_addr;	/* User specified end address */
+	unsigned short perc_atmid;	/* PER trap ATMID */
+	unsigned long address;		/* PER trap instruction address */
+	unsigned char access_id;	/* PER trap access identification */
+};
+
+#define PER_EVENT_MASK			0xE9000000UL
+
+#define PER_EVENT_BRANCH		0x80000000UL
+#define PER_EVENT_IFETCH		0x40000000UL
+#define PER_EVENT_STORE			0x20000000UL
+#define PER_EVENT_STORE_REAL		0x08000000UL
+#define PER_EVENT_NULLIFICATION		0x01000000UL
+
+#define PER_CONTROL_MASK		0x00a00000UL
+
+#define PER_CONTROL_BRANCH_ADDRESS	0x00800000UL
+#define PER_CONTROL_ALTERATION		0x00200000UL
+
 #endif
 
 /*
- * Now for the program event recording (trace) definitions.
+ * Now for the user space program event recording (trace) definitions.
+ * The following structures are used only for the ptrace interface, don't
+ * touch or even look at it if you don't want to modify the user-space
+ * ptrace interface. In particular stay away from it for in-kernel PER.
  */
 typedef struct
 {

arch/s390/include/asm/system.h

@@ -20,6 +20,7 @@
 struct task_struct;
 
 extern struct task_struct *__switch_to(void *, void *);
+extern void update_per_regs(struct task_struct *task);
 
 static inline void save_fp_regs(s390_fp_regs *fpregs)
 {
@@ -93,6 +94,7 @@ static inline void restore_access_regs(unsigned int *acrs)
 	if (next->mm) {							\
 		restore_fp_regs(&next->thread.fp_regs);			\
 		restore_access_regs(&next->thread.acrs[0]);		\
+		update_per_regs(next);					\
 	}								\
 	prev = __switch_to(prev,next);					\
 } while (0)

arch/s390/include/asm/thread_info.h

@@ -88,7 +88,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SIGPENDING		2	/* signal pending */
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_RESTART_SVC		4	/* restart svc with new svc number */
-#define TIF_SINGLE_STEP		6	/* deliver sigtrap on return to user */
+#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 */
@@ -99,21 +99,23 @@ static inline struct thread_info *current_thread_info(void)
 #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_FREEZE		20	/* thread is freezing for suspend */
+#define TIF_SINGLE_STEP		20	/* This task is single stepped */
+#define TIF_FREEZE		21	/* thread is freezing for suspend */
 
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_RESTORE_SIGMASK	(1<<TIF_RESTORE_SIGMASK)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)
 #define _TIF_RESTART_SVC	(1<<TIF_RESTART_SVC)
-#define _TIF_SINGLE_STEP	(1<<TIF_SINGLE_STEP)
+#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)
 #define _TIF_SYSCALL_TRACEPOINT	(1<<TIF_SYSCALL_TRACEPOINT)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 #define _TIF_31BIT		(1<<TIF_31BIT)
+#define _TIF_SINGLE_STEP	(1<<TIF_FREEZE)
 #define _TIF_FREEZE		(1<<TIF_FREEZE)
 
 #endif /* __KERNEL__ */

arch/s390/kernel/asm-offsets.c

@@ -23,14 +23,16 @@ int main(void)
 {
 	DEFINE(__THREAD_info, offsetof(struct task_struct, stack));
 	DEFINE(__THREAD_ksp, offsetof(struct task_struct, thread.ksp));
-	DEFINE(__THREAD_per, offsetof(struct task_struct, thread.per_info));
 	DEFINE(__THREAD_mm_segment, offsetof(struct task_struct, thread.mm_segment));
 	BLANK();
 	DEFINE(__TASK_pid, offsetof(struct task_struct, pid));
 	BLANK();
-	DEFINE(__PER_atmid, offsetof(per_struct, lowcore.words.perc_atmid));
-	DEFINE(__PER_address, offsetof(per_struct, lowcore.words.address));
-	DEFINE(__PER_access_id, offsetof(per_struct, lowcore.words.access_id));
+	DEFINE(__THREAD_per_cause,
+	       offsetof(struct task_struct, thread.per_event.cause));
+	DEFINE(__THREAD_per_address,
+	       offsetof(struct task_struct, thread.per_event.address));
+	DEFINE(__THREAD_per_paid,
+	       offsetof(struct task_struct, thread.per_event.paid));
 	BLANK();
 	DEFINE(__TI_task, offsetof(struct thread_info, task));
 	DEFINE(__TI_domain, offsetof(struct thread_info, exec_domain));
@@ -85,9 +87,9 @@ int main(void)
 	DEFINE(__LC_PGM_ILC, offsetof(struct _lowcore, pgm_ilc));
 	DEFINE(__LC_PGM_INT_CODE, offsetof(struct _lowcore, pgm_code));
 	DEFINE(__LC_TRANS_EXC_CODE, offsetof(struct _lowcore, trans_exc_code));
-	DEFINE(__LC_PER_ATMID, offsetof(struct _lowcore, per_perc_atmid));
+	DEFINE(__LC_PER_CAUSE, offsetof(struct _lowcore, per_perc_atmid));
 	DEFINE(__LC_PER_ADDRESS, offsetof(struct _lowcore, per_address));
-	DEFINE(__LC_PER_ACCESS_ID, offsetof(struct _lowcore, per_access_id));
+	DEFINE(__LC_PER_PAID, offsetof(struct _lowcore, per_access_id));
 	DEFINE(__LC_AR_MODE_ID, offsetof(struct _lowcore, ar_access_id));
 	DEFINE(__LC_SUBCHANNEL_ID, offsetof(struct _lowcore, subchannel_id));
 	DEFINE(__LC_SUBCHANNEL_NR, offsetof(struct _lowcore, subchannel_nr));

arch/s390/kernel/compat_ptrace.h

@@ -4,40 +4,19 @@
 #include <asm/ptrace.h>    /* needed for NUM_CR_WORDS */
 #include "compat_linux.h"  /* needed for psw_compat_t */
 
-typedef struct {
-	__u32 cr[NUM_CR_WORDS];
-} per_cr_words32;
-
-typedef struct {
-	__u16          perc_atmid;          /* 0x096 */
-	__u32          address;             /* 0x098 */
-	__u8           access_id;           /* 0x0a1 */
-} per_lowcore_words32;
-
-typedef struct {
-	union {
-		per_cr_words32   words;
-	} control_regs;
-	/*
-	 * Use these flags instead of setting em_instruction_fetch
-	 * directly they are used so that single stepping can be
-	 * switched on & off while not affecting other tracing
-	 */
-	unsigned  single_step       : 1;
-	unsigned  instruction_fetch : 1;
-	unsigned                    : 30;
-	/*
-	 * These addresses are copied into cr10 & cr11 if single
-	 * stepping is switched off
-	 */
-	__u32     starting_addr;
-	__u32     ending_addr;
-	union {
-		per_lowcore_words32 words;
-	} lowcore; 
-} per_struct32;
+struct compat_per_struct_kernel {
+	__u32 cr9;		/* PER control bits */
+	__u32 cr10;		/* PER starting address */
+	__u32 cr11;		/* PER ending address */
+	__u32 bits;		/* Obsolete software bits */
+	__u32 starting_addr;	/* User specified start address */
+	__u32 ending_addr;	/* User specified end address */
+	__u16 perc_atmid;	/* PER trap ATMID */
+	__u32 address;		/* PER trap instruction address */
+	__u8  access_id;	/* PER trap access identification */
+};
 
-struct user_regs_struct32
+struct compat_user_regs_struct
 {
 	psw_compat_t psw;
 	u32 gprs[NUM_GPRS];
@@ -50,14 +29,14 @@ struct user_regs_struct32
 	 * itself as there is no "official" ptrace interface for hardware
 	 * watchpoints. This is the way intel does it.
 	 */
-	per_struct32 per_info;
+	struct compat_per_struct_kernel per_info;
 	u32  ieee_instruction_pointer;	/* obsolete, always 0 */
 };
 
-struct user32 {
+struct compat_user {
 	/* We start with the registers, to mimic the way that "memory"
 	   is returned from the ptrace(3,...) function.  */
-	struct user_regs_struct32 regs; /* Where the registers are actually stored */
+	struct compat_user_regs_struct regs;
 	/* The rest of this junk is to help gdb figure out what goes where */
 	u32 u_tsize;		/* Text segment size (pages). */
 	u32 u_dsize;	        /* Data segment size (pages). */
@@ -79,6 +58,6 @@ typedef struct
 	__u32   len;
 	__u32   kernel_addr;
 	__u32   process_addr;
-} ptrace_area_emu31;
+} compat_ptrace_area;
 
 #endif /* _PTRACE32_H */

arch/s390/kernel/entry.S

@@ -48,7 +48,7 @@ SP_SVCNR     =	STACK_FRAME_OVERHEAD + __PT_SVCNR
 SP_SIZE      =	STACK_FRAME_OVERHEAD + __PT_SIZE
 
 _TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
-		 _TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
+		 _TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_PER_TRAP )
 _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
 		 _TIF_MCCK_PENDING)
 _TIF_SYSCALL = (_TIF_SYSCALL_TRACE>>8 | _TIF_SYSCALL_AUDIT>>8 | \
@@ -200,31 +200,21 @@ STACK_SIZE  = 1 << STACK_SHIFT
 	.globl	__switch_to
 __switch_to:
 	basr	%r1,0
-__switch_to_base:
-	tm	__THREAD_per(%r3),0xe8		# new process is using per ?
-	bz	__switch_to_noper-__switch_to_base(%r1)	# if not we're fine
-	stctl	%c9,%c11,__SF_EMPTY(%r15)	# We are using per stuff
-	clc	__THREAD_per(12,%r3),__SF_EMPTY(%r15)
-	be	__switch_to_noper-__switch_to_base(%r1)	# we got away w/o bashing TLB's
-	lctl	%c9,%c11,__THREAD_per(%r3)	# Nope we didn't
-__switch_to_noper:
-	l	%r4,__THREAD_info(%r2)		# get thread_info of prev
+0:	l	%r4,__THREAD_info(%r2)		# get thread_info of prev
+	l	%r5,__THREAD_info(%r3)		# get thread_info of next
 	tm	__TI_flags+3(%r4),_TIF_MCCK_PENDING # machine check pending?
-	bz	__switch_to_no_mcck-__switch_to_base(%r1)
-	ni	__TI_flags+3(%r4),255-_TIF_MCCK_PENDING # clear flag in prev
-	l	%r4,__THREAD_info(%r3)		# get thread_info of next
-	oi	__TI_flags+3(%r4),_TIF_MCCK_PENDING # set it in next
-__switch_to_no_mcck:
-	stm	%r6,%r15,__SF_GPRS(%r15)# store __switch_to registers of prev task
-	st	%r15,__THREAD_ksp(%r2)	# store kernel stack to prev->tss.ksp
-	l	%r15,__THREAD_ksp(%r3)	# load kernel stack from next->tss.ksp
-	lm	%r6,%r15,__SF_GPRS(%r15)# load __switch_to registers of next task
-	st	%r3,__LC_CURRENT	# __LC_CURRENT = current task struct
-	lctl	%c4,%c4,__TASK_pid(%r3) # load pid to control reg. 4
-	l	%r3,__THREAD_info(%r3)	# load thread_info from task struct
-	st	%r3,__LC_THREAD_INFO
-	ahi	%r3,STACK_SIZE
-	st	%r3,__LC_KERNEL_STACK	# __LC_KERNEL_STACK = new kernel stack
+	bz	1f-0b(%r1)
+	ni	__TI_flags+3(%r4),255-_TIF_MCCK_PENDING	# clear flag in prev
+	oi	__TI_flags+3(%r5),_TIF_MCCK_PENDING	# set it in next
+1:	stm	%r6,%r15,__SF_GPRS(%r15)	# store gprs of prev task
+	st	%r15,__THREAD_ksp(%r2)		# store kernel stack of prev
+	l	%r15,__THREAD_ksp(%r3)		# load kernel stack of next
+	lctl	%c4,%c4,__TASK_pid(%r3)		# load pid to control reg. 4
+	lm	%r6,%r15,__SF_GPRS(%r15)	# load gprs of next task
+	st	%r3,__LC_CURRENT		# store task struct of next
+	st	%r5,__LC_THREAD_INFO		# store thread info of next
+	ahi	%r5,STACK_SIZE			# end of kernel stack of next
+	st	%r5,__LC_KERNEL_STACK		# store end of kernel stack
 	br	%r14
 
 __critical_start:
@@ -297,7 +287,7 @@ sysc_work_tif:
 	bo	BASED(sysc_notify_resume)
 	tm	__TI_flags+3(%r12),_TIF_RESTART_SVC
 	bo	BASED(sysc_restart)
-	tm	__TI_flags+3(%r12),_TIF_SINGLE_STEP
+	tm	__TI_flags+3(%r12),_TIF_PER_TRAP
 	bo	BASED(sysc_singlestep)
 	b	BASED(sysc_return)	# beware of critical section cleanup
 
@@ -321,13 +311,13 @@ sysc_mcck_pending:
 # _TIF_SIGPENDING is set, call do_signal
 #
 sysc_sigpending:
-	ni	__TI_flags+3(%r12),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
+	ni	__TI_flags+3(%r12),255-_TIF_PER_TRAP # clear TIF_PER_TRAP
 	la	%r2,SP_PTREGS(%r15)	# load pt_regs
 	l	%r1,BASED(.Ldo_signal)
 	basr	%r14,%r1		# call do_signal
 	tm	__TI_flags+3(%r12),_TIF_RESTART_SVC
 	bo	BASED(sysc_restart)
-	tm	__TI_flags+3(%r12),_TIF_SINGLE_STEP
+	tm	__TI_flags+3(%r12),_TIF_PER_TRAP
 	bo	BASED(sysc_singlestep)
 	b	BASED(sysc_return)
 
@@ -353,15 +343,15 @@ sysc_restart:
 	b	BASED(sysc_nr_ok)	# restart svc
 
 #
-# _TIF_SINGLE_STEP is set, call do_single_step
+# _TIF_PER_TRAP is set, call do_per_trap
 #
 sysc_singlestep:
-	ni	__TI_flags+3(%r12),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
+	ni	__TI_flags+3(%r12),255-_TIF_PER_TRAP # clear TIF_PER_TRAP
 	xc	SP_SVCNR(2,%r15),SP_SVCNR(%r15)		# clear svc number
 	la	%r2,SP_PTREGS(%r15)	# address of register-save area
 	l	%r1,BASED(.Lhandle_per)	# load adr. of per handler
 	la	%r14,BASED(sysc_return)	# load adr. of system return
-	br	%r1			# branch to do_single_step
+	br	%r1			# branch to do_per_trap
 
 #
 # call tracehook_report_syscall_entry/tracehook_report_syscall_exit before
@@ -520,10 +510,10 @@ pgm_no_vtime2:
 	l	%r1,__TI_task(%r12)
 	tm	SP_PSW+1(%r15),0x01	# kernel per event ?
 	bz	BASED(kernel_per)
-	mvc	__THREAD_per+__PER_atmid(2,%r1),__LC_PER_ATMID
-	mvc	__THREAD_per+__PER_address(4,%r1),__LC_PER_ADDRESS
-	mvc	__THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
-	oi	__TI_flags+3(%r12),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
+	mvc	__THREAD_per_cause(2,%r1),__LC_PER_CAUSE
+	mvc	__THREAD_per_address(4,%r1),__LC_PER_ADDRESS
+	mvc	__THREAD_per_paid(1,%r1),__LC_PER_PAID
+	oi	__TI_flags+3(%r12),_TIF_PER_TRAP # set TIF_PER_TRAP
 	l	%r3,__LC_PGM_ILC	# load program interruption code
 	l	%r4,__LC_TRANS_EXC_CODE
 	REENABLE_IRQS
@@ -551,10 +541,10 @@ pgm_svcper:
 	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
 	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
 	l	%r8,__TI_task(%r12)
-	mvc	__THREAD_per+__PER_atmid(2,%r8),__LC_PER_ATMID
-	mvc	__THREAD_per+__PER_address(4,%r8),__LC_PER_ADDRESS
-	mvc	__THREAD_per+__PER_access_id(1,%r8),__LC_PER_ACCESS_ID
-	oi	__TI_flags+3(%r12),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
+	mvc	__THREAD_per_cause(2,%r8),__LC_PER_CAUSE
+	mvc	__THREAD_per_address(4,%r8),__LC_PER_ADDRESS
+	mvc	__THREAD_per_paid(1,%r8),__LC_PER_PAID
+	oi	__TI_flags+3(%r12),_TIF_PER_TRAP # set TIF_PER_TRAP
 	stosm	__SF_EMPTY(%r15),0x03	# reenable interrupts
 	lm	%r2,%r6,SP_R2(%r15)	# load svc arguments
 	b	BASED(sysc_do_svc)
@@ -1056,7 +1046,7 @@ cleanup_io_restore_insn:
 .Ldo_signal:	.long	do_signal
 .Ldo_notify_resume:
 		.long	do_notify_resume
-.Lhandle_per:	.long	do_single_step
+.Lhandle_per:	.long	do_per_trap
 .Ldo_execve:	.long	do_execve
 .Lexecve_tail:	.long	execve_tail
 .Ljump_table:	.long	pgm_check_table

arch/s390/kernel/entry.h

@@ -12,7 +12,7 @@ pgm_check_handler_t do_dat_exception;
 
 extern int sysctl_userprocess_debug;
 
-void do_single_step(struct pt_regs *regs);
+void do_per_trap(struct pt_regs *regs);
 void syscall_trace(struct pt_regs *regs, int entryexit);
 void kernel_stack_overflow(struct pt_regs * regs);
 void do_signal(struct pt_regs *regs);