[S390] ptrace changes

* System call parameter and result access functions
* Add tracehook calls
* Split syscall_trace into two functions do_syscall_trace_enter and
  do_syscall_trace_exit

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

8 files changed, 202 insertions, 48 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 8d41908..4c03049 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -74,6 +74,7 @@ config S390
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_KVM if 64BIT
+	select HAVE_ARCH_TRACEHOOK
 
 source "init/Kconfig"
 
diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index af2c9ac..a7226f8 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -490,6 +490,7 @@ extern void user_disable_single_step(struct task_struct *);
 
 #define user_mode(regs) (((regs)->psw.mask & PSW_MASK_PSTATE) != 0)
 #define instruction_pointer(regs) ((regs)->psw.addr & PSW_ADDR_INSN)
+#define user_stack_pointer(regs)((regs)->gprs[15])
 #define regs_return_value(regs)((regs)->gprs[2])
 #define profile_pc(regs) instruction_pointer(regs)
 extern void show_regs(struct pt_regs * regs);
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
new file mode 100644
index 0000000..6e62397
--- /dev/null
+++ b/arch/s390/include/asm/syscall.h
@@ -0,0 +1,80 @@
+/*
+ * Access to user system call parameters and results
+ *
+ *  Copyright IBM Corp. 2008
+ *  Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_SYSCALL_H
+#define _ASM_SYSCALL_H	1
+
+#include <asm/ptrace.h>
+
+static inline long syscall_get_nr(struct task_struct *task,
+				  struct pt_regs *regs)
+{
+	if (regs->trap != __LC_SVC_OLD_PSW)
+		return -1;
+	return regs->gprs[2];
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+				    struct pt_regs *regs)
+{
+	regs->gprs[2] = regs->orig_gpr2;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	return (regs->gprs[2] >= -4096UL) ? -regs->gprs[2] : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	return regs->gprs[2];
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	regs->gprs[2] = error ? -error : val;
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 unsigned long *args)
+{
+	BUG_ON(i + n > 6);
+#ifdef CONFIG_COMPAT
+	if (test_tsk_thread_flag(task, TIF_31BIT)) {
+		if (i + n == 6)
+			args[--n] = (u32) regs->args[0];
+		while (n-- > 0)
+			args[n] = (u32) regs->gprs[2 + i + n];
+	}
+#endif
+	if (i + n == 6)
+		args[--n] = regs->args[0];
+	memcpy(args, &regs->gprs[2 + i], n * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 const unsigned long *args)
+{
+	BUG_ON(i + n > 6);
+	if (i + n == 6)
+		regs->args[0] = args[--n];
+	memcpy(&regs->gprs[2 + i], args, n * sizeof(args[0]));
+}
+
+#endif	/* _ASM_SYSCALL_H */
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index 91a8f93..ea40a9d 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -86,6 +86,7 @@ static inline struct thread_info *current_thread_info(void)
  * thread information flags bit numbers
  */
 #define TIF_SYSCALL_TRACE	0	/* syscall trace active */
+#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_RESTART_SVC		4	/* restart svc with new svc number */
@@ -100,6 +101,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_RESTORE_SIGMASK	20	/* restore signal mask in do_signal() */
 
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
+#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)
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 708cf9c..ed500ef 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -49,9 +49,9 @@ SP_ILC	     =	STACK_FRAME_OVERHEAD + __PT_ILC
 SP_TRAP      =	STACK_FRAME_OVERHEAD + __PT_TRAP
 SP_SIZE      =	STACK_FRAME_OVERHEAD + __PT_SIZE
 
-_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
 		 _TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
-_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
 		 _TIF_MCCK_PENDING)
 
 STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
@@ -318,6 +318,8 @@ sysc_work:
 	bo	BASED(sysc_reschedule)
 	tm	__TI_flags+3(%r9),_TIF_SIGPENDING
 	bnz	BASED(sysc_sigpending)
+	tm	__TI_flags+3(%r9),_TIF_NOTIFY_RESUME
+	bnz	BASED(sysc_notify_resume)
 	tm	__TI_flags+3(%r9),_TIF_RESTART_SVC
 	bo	BASED(sysc_restart)
 	tm	__TI_flags+3(%r9),_TIF_SINGLE_STEP
@@ -356,6 +358,16 @@ sysc_sigpending:
 	b	BASED(sysc_work_loop)
 
 #
+# _TIF_NOTIFY_RESUME is set, call do_notify_resume
+#
+sysc_notify_resume:
+	la	%r2,SP_PTREGS(%r15)	# load pt_regs
+	l	%r1,BASED(.Ldo_notify_resume)
+	la	%r14,BASED(sysc_work_loop)
+	br	%r1			# call do_notify_resume
+
+
+#
 # _TIF_RESTART_SVC is set, set up registers and restart svc
 #
 sysc_restart:
@@ -378,20 +390,21 @@ sysc_singlestep:
 	br	%r1			# branch to do_single_step
 
 #
-# call trace before and after sys_call
+# call tracehook_report_syscall_entry/tracehook_report_syscall_exit before
+# and after the system call
 #
 sysc_tracesys:
-	l	%r1,BASED(.Ltrace)
+	l	%r1,BASED(.Ltrace_entry)
 	la	%r2,SP_PTREGS(%r15)	# load pt_regs
 	la	%r3,0
 	srl	%r7,2
 	st	%r7,SP_R2(%r15)
 	basr	%r14,%r1
-	clc	SP_R2(4,%r15),BASED(.Lnr_syscalls)
+	cl	%r2,BASED(.Lnr_syscalls)
 	bnl	BASED(sysc_tracenogo)
 	l	%r8,BASED(.Lsysc_table)
-	l	%r7,SP_R2(%r15) 	# strace might have changed the
-	sll	%r7,2			#  system call
+	lr	%r7,%r2
+	sll	%r7,2			# *4
 	l	%r8,0(%r7,%r8)
 sysc_tracego:
 	lm	%r3,%r6,SP_R3(%r15)
@@ -401,9 +414,8 @@ sysc_tracego:
 sysc_tracenogo:
 	tm	__TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
 	bz	BASED(sysc_return)
-	l	%r1,BASED(.Ltrace)
+	l	%r1,BASED(.Ltrace_exit)
 	la	%r2,SP_PTREGS(%r15)	# load pt_regs
-	la	%r3,1
 	la	%r14,BASED(sysc_return)
 	br	%r1
 
@@ -666,6 +678,8 @@ io_work_loop:
 	bo	BASED(io_reschedule)
 	tm	__TI_flags+3(%r9),_TIF_SIGPENDING
 	bnz	BASED(io_sigpending)
+	tm	__TI_flags+3(%r9),_TIF_NOTIFY_RESUME
+	bnz	BASED(io_notify_resume)
 	b	BASED(io_restore)
 io_work_done:
 
@@ -704,6 +718,19 @@ io_sigpending:
 	TRACE_IRQS_OFF
 	b	BASED(io_work_loop)
 
+#
+# _TIF_SIGPENDING is set, call do_signal
+#
+io_notify_resume:
+	TRACE_IRQS_ON
+	stosm	__SF_EMPTY(%r15),0x03	# reenable interrupts
+	la	%r2,SP_PTREGS(%r15)	# load pt_regs
+	l	%r1,BASED(.Ldo_notify_resume)
+	basr	%r14,%r1		# call do_signal
+	stnsm	__SF_EMPTY(%r15),0xfc	# disable I/O and ext. interrupts
+	TRACE_IRQS_OFF
+	b	BASED(io_work_loop)
+
 /*
  * External interrupt handler routine
  */
@@ -1070,6 +1097,8 @@ cleanup_io_leave_insn:
 .Ldo_IRQ:	.long	do_IRQ
 .Ldo_extint:	.long	do_extint
 .Ldo_signal:	.long	do_signal
+.Ldo_notify_resume:
+		.long	do_notify_resume
 .Lhandle_per:	.long	do_single_step
 .Ldo_execve:	.long	do_execve
 .Lexecve_tail:	.long	execve_tail
@@ -1079,7 +1108,8 @@ cleanup_io_leave_insn:
 .Lpreempt_schedule_irq:
 		.long	preempt_schedule_irq
 #endif
-.Ltrace:	.long	syscall_trace
+.Ltrace_entry:	.long	do_syscall_trace_enter
+.Ltrace_exit:	.long	do_syscall_trace_exit
 .Lschedtail:	.long	schedule_tail
 .Lsysc_table:	.long	sys_call_table
 #ifdef CONFIG_TRACE_IRQFLAGS
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index fee1017..d7ce150 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -52,9 +52,9 @@ SP_SIZE      =	STACK_FRAME_OVERHEAD + __PT_SIZE
 STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
 STACK_SIZE  = 1 << STACK_SHIFT
 
-_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
 		 _TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
-_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
 		 _TIF_MCCK_PENDING)
 
 #define BASED(name) name-system_call(%r13)
@@ -310,6 +310,8 @@ sysc_work:
 	jo	sysc_reschedule
 	tm	__TI_flags+7(%r9),_TIF_SIGPENDING
 	jnz	sysc_sigpending
+	tm	__TI_flags+7(%r9),_TIF_NOTIFY_RESUME
+	jnz	sysc_notify_resume
 	tm	__TI_flags+7(%r9),_TIF_RESTART_SVC
 	jo	sysc_restart
 	tm	__TI_flags+7(%r9),_TIF_SINGLE_STEP
@@ -345,6 +347,14 @@ sysc_sigpending:
 	j	sysc_work_loop
 
 #
+# _TIF_NOTIFY_RESUME is set, call do_notify_resume
+#
+sysc_notify_resume:
+	la	%r2,SP_PTREGS(%r15)	# load pt_regs
+	larl	%r14,sysc_work_loop
+	jg	do_notify_resume	# call do_notify_resume
+
+#
 # _TIF_RESTART_SVC is set, set up registers and restart svc
 #
 sysc_restart:
@@ -367,20 +377,19 @@ sysc_singlestep:
 	jg	do_single_step		# branch to do_sigtrap
 
 #
-# call syscall_trace before and after system call
-# special linkage: %r12 contains the return address for trace_svc
+# call tracehook_report_syscall_entry/tracehook_report_syscall_exit before
+# and after the system call
 #
 sysc_tracesys:
 	la	%r2,SP_PTREGS(%r15)	# load pt_regs
 	la	%r3,0
 	srl	%r7,2
 	stg	%r7,SP_R2(%r15)
-	brasl	%r14,syscall_trace
+	brasl	%r14,do_syscall_trace_enter
 	lghi	%r0,NR_syscalls
-	clg	%r0,SP_R2(%r15)
+	clgr	%r0,%r2
 	jnh	sysc_tracenogo
-	lg	%r7,SP_R2(%r15)		# strace might have changed the
-	sll	%r7,2			# system call
+	slag	%r7,%r2,2		# *4
 	lgf	%r8,0(%r7,%r10)
 sysc_tracego:
 	lmg	%r3,%r6,SP_R3(%r15)
@@ -391,9 +400,8 @@ sysc_tracenogo:
 	tm	__TI_flags+7(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
 	jz	sysc_return
 	la	%r2,SP_PTREGS(%r15)	# load pt_regs
-	la	%r3,1
 	larl	%r14,sysc_return	# return point is sysc_return
-	jg	syscall_trace
+	jg	do_syscall_trace_exit
 
 #
 # a new process exits the kernel with ret_from_fork
@@ -672,6 +680,8 @@ io_work_loop:
 	jo	io_reschedule
 	tm	__TI_flags+7(%r9),_TIF_SIGPENDING
 	jnz	io_sigpending
+	tm	__TI_flags+7(%r9),_TIF_NOTIFY_RESUME
+	jnz	io_notify_resume
 	j	io_restore
 io_work_done:
 
@@ -712,6 +722,18 @@ io_sigpending:
 	TRACE_IRQS_OFF
 	j	io_work_loop
 
+#
+# _TIF_NOTIFY_RESUME or is set, call do_notify_resume
+#
+io_notify_resume:
+	TRACE_IRQS_ON
+	stosm	__SF_EMPTY(%r15),0x03	# reenable interrupts
+	la	%r2,SP_PTREGS(%r15)	# load pt_regs
+	brasl	%r14,do_notify_resume	# call do_notify_resume
+	stnsm	__SF_EMPTY(%r15),0xfc	# disable I/O and ext. interrupts
+	TRACE_IRQS_OFF
+	j	io_work_loop
+
 /*
  * External interrupt handler routine
  */
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index c8b0828..1f31be1 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -35,6 +35,7 @@
 #include <linux/signal.h>
 #include <linux/elf.h>
 #include <linux/regset.h>
+#include <linux/tracehook.h>
 
 #include <asm/segment.h>
 #include <asm/page.h>
@@ -639,40 +640,44 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 }
 #endif
 
-asmlinkage void
-syscall_trace(struct pt_regs *regs, int entryexit)
+asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
 {
-	if (unlikely(current->audit_context) && entryexit)
-		audit_syscall_exit(AUDITSC_RESULT(regs->gprs[2]), regs->gprs[2]);
-
-	if (!test_thread_flag(TIF_SYSCALL_TRACE))
-		goto out;
-	if (!(current->ptrace & PT_PTRACED))
-		goto out;
-	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
-				 ? 0x80 : 0));
+	long ret;
 
 	/*
-	 * If the debuffer has set an invalid system call number,
-	 * we prepare to skip the system call restart handling.
+	 * The sysc_tracesys code in entry.S stored the system
+	 * call number to gprs[2].
 	 */
-	if (!entryexit && regs->gprs[2] >= NR_syscalls)
+	ret = regs->gprs[2];
+	if (test_thread_flag(TIF_SYSCALL_TRACE) &&
+	    (tracehook_report_syscall_entry(regs) ||
+	     regs->gprs[2] >= NR_syscalls)) {
+		/*
+		 * Tracing decided this syscall should not happen or the
+		 * debugger stored an invalid system call number. Skip
+		 * the system call and the system call restart handling.
+		 */
 		regs->trap = -1;
-
-	/*
-	 * this isn't the same as continuing with a signal, but it will do
-	 * for normal use.  strace only continues with a signal if the
-	 * stopping signal is not SIGTRAP.  -brl
-	 */
-	if (current->exit_code) {
-		send_sig(current->exit_code, current, 1);
-		current->exit_code = 0;
+		ret = -1;
 	}
- out:
-	if (unlikely(current->audit_context) && !entryexit)
-		audit_syscall_entry(test_thread_flag(TIF_31BIT)?AUDIT_ARCH_S390:AUDIT_ARCH_S390X,
-				    regs->gprs[2], regs->orig_gpr2, regs->gprs[3],
-				    regs->gprs[4], regs->gprs[5]);
+
+	if (unlikely(current->audit_context))
+		audit_syscall_entry(test_thread_flag(TIF_31BIT) ?
+					AUDIT_ARCH_S390 : AUDIT_ARCH_S390X,
+				    regs->gprs[2], regs->orig_gpr2,
+				    regs->gprs[3], regs->gprs[4],
+				    regs->gprs[5]);
+	return ret;
+}
+
+asmlinkage void do_syscall_trace_exit(struct pt_regs *regs)
+{
+	if (unlikely(current->audit_context))
+		audit_syscall_exit(AUDITSC_RESULT(regs->gprs[2]),
+				   regs->gprs[2]);
+
+	if (test_thread_flag(TIF_SYSCALL_TRACE))
+		tracehook_report_syscall_exit(regs, 0);
 }
 
 /*
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index b976820..4f7fc30 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -24,6 +24,7 @@
 #include <linux/tty.h>
 #include <linux/personality.h>
 #include <linux/binfmts.h>
+#include <linux/tracehook.h>
 #include <asm/ucontext.h>
 #include <asm/uaccess.h>
 #include <asm/lowcore.h>
@@ -507,6 +508,12 @@ void do_signal(struct pt_regs *regs)
 			 */
 			if (current->thread.per_info.single_step)
 				set_thread_flag(TIF_SINGLE_STEP);
+
+			/*
+			 * Let tracing know that we've done the handler setup.
+			 */
+			tracehook_signal_handler(signr, &info, &ka, regs,
+					 test_thread_flag(TIF_SINGLE_STEP));
 		}
 		return;
 	}
@@ -526,3 +533,9 @@ void do_signal(struct pt_regs *regs)
 		set_thread_flag(TIF_RESTART_SVC);
 	}
 }
+
+void do_notify_resume(struct pt_regs *regs)
+{
+	clear_thread_flag(TIF_NOTIFY_RESUME);
+	tracehook_notify_resume(regs);
+}