[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 8d41908e2513..4c03049e7db9 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 af2c9ac28a07..a7226f8143fb 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 000000000000..6e623971fbb9
--- /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 91a8f93ad355..ea40a9d690fc 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 708cf9cf9a35..ed500ef799b7 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 fee10177dbfc..d7ce150453f2 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 c8b08289eb87..1f31be1ecc4b 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 b97682040215..4f7fc3059a8e 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);
+}