sh: Make syscall tracer use tracehook notifiers, add TIF_NOTIFY_RESUME.

This follows the changes in commits:

7d6d637dac2050f30a1b57b0a3dc5de4a10616ba
4f72c4279eab1e5f3ed1ac4e55d4527617582392

on powerpc. Adding in TIF_NOTIFY_RESUME, and cleaning up the syscall
tracing to be more generic. This is an incremental step to turning
on tracehook, as well as unifying more of the ptrace and signal code
across the 32/64 split.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

6 files changed, 167 insertions, 154 deletions

diff --git a/arch/sh/kernel/cpu/sh5/entry.S b/arch/sh/kernel/cpu/sh5/entry.S
index bba331d5ef74..04c7da968146 100644
--- a/arch/sh/kernel/cpu/sh5/entry.S
+++ b/arch/sh/kernel/cpu/sh5/entry.S
@@ -987,11 +987,11 @@ work_resched:
 work_notifysig:
         gettr   tr1, LINK
 
-        movi    do_signal, r6
+        movi    do_notify_resume, r6
         ptabs   r6, tr0
         or      SP, ZERO, r2
-        or      ZERO, ZERO, r3
-        blink   tr0, LINK           /* Call do_signal(regs, 0), return here */
+        or      r7, ZERO, r3
+        blink   tr0, LINK           /* Call do_notify_resume(regs, current_thread_info->flags), return here */
 
 restore_all:
         /* Do prefetches */
@@ -1305,13 +1305,15 @@ syscall_allowed:
         beq/l   r6, ZERO, tr0
 
         /* Trace it by calling syscall_trace before and after */
-        movi    syscall_trace, r4
+        movi    do_syscall_trace_enter, r4
         or      SP, ZERO, r2
-        or      ZERO, ZERO, r3
         ptabs   r4, tr0
         blink   tr0, LINK
 
-        /* Reload syscall number as r5 is trashed by syscall_trace */
+        /* Save the retval */
+        st.q    SP, FRAME_R(2), r2
+
+        /* Reload syscall number as r5 is trashed by do_syscall_trace_enter */
         ld.q    SP, FRAME_S(FSYSCALL_ID), r5
         andi    r5, 0x1ff, r5
 
@@ -1343,9 +1345,8 @@ syscall_ret_trace:
         /* We get back here only if under trace */
         st.q    SP, FRAME_R(9), r2      /* Save return value */
 
-        movi    syscall_trace, LINK
+        movi    do_syscall_trace_leave, LINK
         or      SP, ZERO, r2
-        movi    1, r3
         ptabs   LINK, tr0
         blink   tr0, LINK
 
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
index a34417c8ee0a..0bc17def55a7 100644
--- a/arch/sh/kernel/entry-common.S
+++ b/arch/sh/kernel/entry-common.S
@@ -211,10 +211,8 @@ syscall_exit_work:
          nop
 #endif
         sti
-        ! XXX setup arguments...
         mov     r15, r4
-        mov     #1, r5
-        mov.l   4f, r0                  ! do_syscall_trace
+        mov.l   8f, r0                  ! do_syscall_trace_leave
         jsr     @r0
          nop
         bra     resume_userspace
@@ -223,12 +221,11 @@ syscall_exit_work:
         .align  2
 syscall_trace_entry:
         !                       Yes it is traced.
-        ! XXX setup arguments...
         mov     r15, r4
-        mov     #0, r5
-        mov.l   4f, r11         ! Call do_syscall_trace which notifies
+        mov.l   7f, r11         ! Call do_syscall_trace_enter which notifies
         jsr     @r11            ! superior (will chomp R[0-7])
          nop
+        mov.l   r0, @(OFF_R0,r15)       ! Save return value
         !                       Reload R0-R4 from kernel stack, where the
         !                       parent may have modified them using
         !                       ptrace(POKEUSR).  (Note that R0-R2 are
@@ -389,8 +386,9 @@ syscall_exit:
 #endif
 2:      .long   NR_syscalls
 3:      .long   sys_call_table
-4:      .long   do_syscall_trace
 #ifdef CONFIG_TRACE_IRQFLAGS
 5:      .long   trace_hardirqs_on
 6:      .long   trace_hardirqs_off
 #endif
+7:      .long   do_syscall_trace_enter
+8:      .long   do_syscall_trace_leave
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index ff66f97c564d..f48769b23bd6 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -21,6 +21,7 @@
 #include <linux/io.h>
 #include <linux/audit.h>
 #include <linux/seccomp.h>
+#include <linux/tracehook.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -216,41 +217,38 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
         return ret;
 }
 
-asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
+asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
 {
-        struct task_struct *tsk = current;
+        long ret = 0;
 
         secure_computing(regs->regs[0]);
 
-        if (unlikely(current->audit_context) && entryexit)
-                audit_syscall_exit(AUDITSC_RESULT(regs->regs[0]),
-                                   regs->regs[0]);
-
-        if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
-            !test_thread_flag(TIF_SINGLESTEP))
-                goto out;
-        if (!(tsk->ptrace & PT_PTRACED))
-                goto out;
-
-        /* the 0x80 provides a way for the tracing parent to distinguish
-           between a syscall stop and SIGTRAP delivery */
-        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
-                                 !test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
-
-        /*
-         * 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 (tsk->exit_code) {
-                send_sig(tsk->exit_code, tsk, 1);
-                tsk->exit_code = 0;
-        }
+        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
+            tracehook_report_syscall_entry(regs))
+                /*
+                 * Tracing decided this syscall should not happen.
+                 * We'll return a bogus call number to get an ENOSYS
+                 * error, but leave the original number in regs->regs[0].
+                 */
+                ret = -1L;
 
-out:
-        if (unlikely(current->audit_context) && !entryexit)
+        if (unlikely(current->audit_context))
                 audit_syscall_entry(AUDIT_ARCH_SH, regs->regs[3],
                                     regs->regs[4], regs->regs[5],
                                     regs->regs[6], regs->regs[7]);
 
+        return ret ?: regs->regs[0];
+}
+
+asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
+{
+        int step;
+
+        if (unlikely(current->audit_context))
+                audit_syscall_exit(AUDITSC_RESULT(regs->regs[0]),
+                                   regs->regs[0]);
+
+        step = test_thread_flag(TIF_SINGLESTEP);
+        if (step || test_thread_flag(TIF_SYSCALL_TRACE))
+                tracehook_report_syscall_exit(regs, step);
 }
diff --git a/arch/sh/kernel/ptrace_64.c b/arch/sh/kernel/ptrace_64.c
index 108f3962e39a..236d8bef9ccd 100644
--- a/arch/sh/kernel/ptrace_64.c
+++ b/arch/sh/kernel/ptrace_64.c
@@ -28,6 +28,7 @@
 #include <linux/syscalls.h>
 #include <linux/audit.h>
 #include <linux/seccomp.h>
+#include <linux/tracehook.h>
 #include <asm/io.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -221,40 +222,37 @@ asmlinkage int sh64_ptrace(long request, long pid, long addr, long data)
         return sys_ptrace(request, pid, addr, data);
 }
 
-asmlinkage void syscall_trace(struct pt_regs *regs, int entryexit)
+asmlinkage long long do_syscall_trace_enter(struct pt_regs *regs)
 {
-        struct task_struct *tsk = current;
+        long long ret = 0;
 
         secure_computing(regs->regs[9]);
 
-        if (unlikely(current->audit_context) && entryexit)
-                audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
-                                   regs->regs[9]);
-
-        if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
-            !test_thread_flag(TIF_SINGLESTEP))
-                goto out;
-        if (!(tsk->ptrace & PT_PTRACED))
-                goto out;
-
-        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) &&
-                                !test_thread_flag(TIF_SINGLESTEP) ? 0x80 : 0));
-
-        /*
-         * 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 (tsk->exit_code) {
-                send_sig(tsk->exit_code, tsk, 1);
-                tsk->exit_code = 0;
-        }
+        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
+            tracehook_report_syscall_entry(regs))
+                /*
+                 * Tracing decided this syscall should not happen.
+                 * We'll return a bogus call number to get an ENOSYS
+                 * error, but leave the original number in regs->regs[0].
+                 */
+                ret = -1LL;
 
-out:
-        if (unlikely(current->audit_context) && !entryexit)
+        if (unlikely(current->audit_context))
                 audit_syscall_entry(AUDIT_ARCH_SH, regs->regs[1],
                                     regs->regs[2], regs->regs[3],
                                     regs->regs[4], regs->regs[5]);
+
+        return ret ?: regs->regs[9];
+}
+
+asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
+{
+        if (unlikely(current->audit_context))
+                audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
+                                   regs->regs[9]);
+
+        if (test_thread_flag(TIF_SYSCALL_TRACE))
+                tracehook_report_syscall_exit(regs, 0);
 }
 
 /* Called with interrupts disabled */
diff --git a/arch/sh/kernel/signal_32.c b/arch/sh/kernel/signal_32.c
index 4bbbde895a53..51689d29ad45 100644
--- a/arch/sh/kernel/signal_32.c
+++ b/arch/sh/kernel/signal_32.c
@@ -24,6 +24,7 @@
 #include <linux/binfmts.h>
 #include <linux/freezer.h>
 #include <linux/io.h>
+#include <linux/tracehook.h>
 #include <asm/system.h>
 #include <asm/ucontext.h>
 #include <asm/uaccess.h>
@@ -507,14 +508,13 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
                 switch (regs->regs[0]) {
                         case -ERESTART_RESTARTBLOCK:
                         case -ERESTARTNOHAND:
+                        no_system_call_restart:
                                 regs->regs[0] = -EINTR;
                                 break;
 
                         case -ERESTARTSYS:
-                                if (!(ka->sa.sa_flags & SA_RESTART)) {
-                                        regs->regs[0] = -EINTR;
-                                        break;
-                                }
+                                if (!(ka->sa.sa_flags & SA_RESTART))
+                                        goto no_system_call_restart;
                         /* fallthrough */
                         case -ERESTARTNOINTR:
                                 regs->regs[0] = save_r0;
@@ -589,12 +589,15 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
                          * clear the TIF_RESTORE_SIGMASK flag */
                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
+
+                        tracehook_signal_handler(signr, &info, &ka, regs,
+                                        test_thread_flag(TIF_SINGLESTEP));
                 }
 
                 return;
         }
 
- no_signal:
+no_signal:
         /* Did we come from a system call? */
         if (regs->tra >= 0) {
                 /* Restart the system call - no handlers present */
@@ -618,9 +621,14 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
 }
 
 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
-                                 __u32 thread_info_flags)
+                                 unsigned long thread_info_flags)
 {
         /* deal with pending signal delivery */
-        if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
+        if (thread_info_flags & _TIF_SIGPENDING)
                 do_signal(regs, save_r0);
+
+        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+                clear_thread_flag(TIF_NOTIFY_RESUME);
+                tracehook_notify_resume(regs);
+        }
 }
diff --git a/arch/sh/kernel/signal_64.c b/arch/sh/kernel/signal_64.c
index 552eb810cd85..1d62dfef77f1 100644
--- a/arch/sh/kernel/signal_64.c
+++ b/arch/sh/kernel/signal_64.c
@@ -22,6 +22,7 @@
 #include <linux/ptrace.h>
 #include <linux/unistd.h>
 #include <linux/stddef.h>
+#include <linux/tracehook.h>
 #include <asm/ucontext.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -42,7 +43,84 @@
 
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
-asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
+/*
+ * Note that 'init' is a special process: it doesn't get signals it doesn't
+ * want to handle. Thus you cannot kill init even with a SIGKILL even by
+ * mistake.
+ *
+ * Note that we go through the signals twice: once to check the signals that
+ * the kernel can handle, and then we build all the user-level signal handling
+ * stack-frames in one go after that.
+ */
+static int do_signal(struct pt_regs *regs, sigset_t *oldset)
+{
+        siginfo_t info;
+        int signr;
+        struct k_sigaction ka;
+
+        /*
+         * We want the common case to go fast, which
+         * is why we may in certain cases get here from
+         * kernel mode. Just return without doing anything
+         * if so.
+         */
+        if (!user_mode(regs))
+                return 1;
+
+        if (try_to_freeze())
+                goto no_signal;
+
+        if (test_thread_flag(TIF_RESTORE_SIGMASK))
+                oldset = &current->saved_sigmask;
+        else if (!oldset)
+                oldset = &current->blocked;
+
+        signr = get_signal_to_deliver(&info, &ka, regs, 0);
+
+        if (signr > 0) {
+                /* Whee!  Actually deliver the signal.  */
+                handle_signal(signr, &info, &ka, oldset, regs);
+
+                /*
+                 * If a signal was successfully delivered, the saved sigmask
+                 * is in its frame, and we can clear the TIF_RESTORE_SIGMASK
+                 * flag.
+                 */
+                if (test_thread_flag(TIF_RESTORE_SIGMASK))
+                        clear_thread_flag(TIF_RESTORE_SIGMASK);
+
+                tracehook_signal_handler(signr, &info, &ka, regs, 0);
+                return 1;
+        }
+
+no_signal:
+        /* Did we come from a system call? */
+        if (regs->syscall_nr >= 0) {
+                /* Restart the system call - no handlers present */
+                switch (regs->regs[REG_RET]) {
+                case -ERESTARTNOHAND:
+                case -ERESTARTSYS:
+                case -ERESTARTNOINTR:
+                        /* Decode Syscall # */
+                        regs->regs[REG_RET] = regs->syscall_nr;
+                        regs->pc -= 4;
+                        break;
+
+                case -ERESTART_RESTARTBLOCK:
+                        regs->regs[REG_RET] = __NR_restart_syscall;
+                        regs->pc -= 4;
+                        break;
+                }
+        }
+
+        /* No signal to deliver -- put the saved sigmask back */
+        if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
+                clear_thread_flag(TIF_RESTORE_SIGMASK);
+                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
+        }
+
+        return 0;
+}
 
 /*
  * Atomically swap in the new signal mask, and wait for a signal.
@@ -643,14 +721,13 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
                 switch (regs->regs[REG_RET]) {
                         case -ERESTART_RESTARTBLOCK:
                         case -ERESTARTNOHAND:
+                        no_system_call_restart:
                                 regs->regs[REG_RET] = -EINTR;
                                 break;
 
                         case -ERESTARTSYS:
-                                if (!(ka->sa.sa_flags & SA_RESTART)) {
-                                        regs->regs[REG_RET] = -EINTR;
-                                        break;
-                                }
+                                if (!(ka->sa.sa_flags & SA_RESTART))
+                                        goto no_system_call_restart;
                         /* fallthrough */
                         case -ERESTARTNOINTR:
                                 /* Decode syscall # */
@@ -673,80 +750,13 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
         spin_unlock_irq(&current->sighand->siglock);
 }
 
-/*
- * Note that 'init' is a special process: it doesn't get signals it doesn't
- * want to handle. Thus you cannot kill init even with a SIGKILL even by
- * mistake.
- *
- * Note that we go through the signals twice: once to check the signals that
- * the kernel can handle, and then we build all the user-level signal handling
- * stack-frames in one go after that.
- */
-int do_signal(struct pt_regs *regs, sigset_t *oldset)
+asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
 {
-        siginfo_t info;
-        int signr;
-        struct k_sigaction ka;
-
-        /*
-         * We want the common case to go fast, which
-         * is why we may in certain cases get here from
-         * kernel mode. Just return without doing anything
-         * if so.
-         */
-        if (!user_mode(regs))
-                return 1;
-
-        if (try_to_freeze())
-                goto no_signal;
-
-        if (test_thread_flag(TIF_RESTORE_SIGMASK))
-                oldset = &current->saved_sigmask;
-        else if (!oldset)
-                oldset = &current->blocked;
-
-        signr = get_signal_to_deliver(&info, &ka, regs, 0);
-
-        if (signr > 0) {
-                /* Whee!  Actually deliver the signal.  */
-                handle_signal(signr, &info, &ka, oldset, regs);
+        if (thread_info_flags & _TIF_SIGPENDING)
+                do_signal(regs, 0);
 
-                /*
-                 * If a signal was successfully delivered, the saved sigmask
-                 * is in its frame, and we can clear the TIF_RESTORE_SIGMASK
-                 * flag.
-                 */
-                if (test_thread_flag(TIF_RESTORE_SIGMASK))
-                        clear_thread_flag(TIF_RESTORE_SIGMASK);
-
-                return 1;
+        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+                clear_thread_flag(TIF_NOTIFY_RESUME);
+                tracehook_notify_resume(regs);
         }
-
-no_signal:
-        /* Did we come from a system call? */
-        if (regs->syscall_nr >= 0) {
-                /* Restart the system call - no handlers present */
-                switch (regs->regs[REG_RET]) {
-                case -ERESTARTNOHAND:
-                case -ERESTARTSYS:
-                case -ERESTARTNOINTR:
-                        /* Decode Syscall # */
-                        regs->regs[REG_RET] = regs->syscall_nr;
-                        regs->pc -= 4;
-                        break;
-
-                case -ERESTART_RESTARTBLOCK:
-                        regs->regs[REG_RET] = __NR_restart_syscall;
-                        regs->pc -= 4;
-                        break;
-                }
-        }
-
-        /* No signal to deliver -- put the saved sigmask back */
-        if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
-                clear_thread_flag(TIF_RESTORE_SIGMASK);
-                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
-        }
-
-        return 0;
 }