ptrace: x86: implement user_single_step_siginfo()

Suggested by Roland.

Implement user_single_step_siginfo() for x86.  Extract this code from
send_sigtrap().

Since x86 calls tracehook_report_syscall_exit(step => 0) the new helper is
not used yet.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: <linux-arch@vger.kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 23 insertions, 9 deletions

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 3d11fd0f44c5..9d369f680321 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -292,6 +292,8 @@ extern void user_enable_block_step(struct task_struct *);
 #define arch_has_block_step()   (boot_cpu_data.x86 >= 6)
 #endif
 
+#define ARCH_HAS_USER_SINGLE_STEP_INFO
+
 struct user_desc;
 extern int do_get_thread_area(struct task_struct *p, int idx,
                               struct user_desc __user *info);
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7079ddaf0731..77b60085a810 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1676,21 +1676,33 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
 #endif
 }
 
-void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
-                                         int error_code, int si_code)
+static void fill_sigtrap_info(struct task_struct *tsk,
+                                struct pt_regs *regs,
+                                int error_code, int si_code,
+                                struct siginfo *info)
 {
-        struct siginfo info;
-
         tsk->thread.trap_no = 1;
         tsk->thread.error_code = error_code;
 
-        memset(&info, 0, sizeof(info));
-        info.si_signo = SIGTRAP;
-        info.si_code = si_code;
+        memset(info, 0, sizeof(*info));
+        info->si_signo = SIGTRAP;
+        info->si_code = si_code;
+        info->si_addr = user_mode_vm(regs) ? (void __user *)regs->ip : NULL;
+}
+
+void user_single_step_siginfo(struct task_struct *tsk,
+                                struct pt_regs *regs,
+                                struct siginfo *info)
+{
+        fill_sigtrap_info(tsk, regs, 0, TRAP_BRKPT, info);
+}
 
-        /* User-mode ip? */
-        info.si_addr = user_mode_vm(regs) ? (void __user *) regs->ip : NULL;
+void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
+                                         int error_code, int si_code)
+{
+        struct siginfo info;
 
+        fill_sigtrap_info(tsk, regs, error_code, si_code, &info);
         /* Send us the fake SIGTRAP */
         force_sig_info(SIGTRAP, &info, tsk);
 }