Add the new internal ptrace flags, PT_SINGLE_STEP and PT_SINGLE_BLOCK. Like PT_SYSCALL_TRACE, this is needed to avoid the unnecessary ptrace reports when TIF_SINGLESTEP was set by another engine, not by ptrace. Also, we need these bits to coordinate the user_*_single_step() calls from ptrace and utrace. TODO: update the !x86 ptrace code which does user_disable_single_step(). Signed-off-by: Oleg Nesterov <oleg(a)redhat.com&gt; --- arch/x86/kernel/ptrace.c | 1 + include/linux/ptrace.h | 5 ++++- include/linux/tracehook.h | 7 +++++-- kernel/ptrace.c | 3 +++ 4 files changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 807c2a2..7ab475f 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -807,6 +807,7 @@ static int ioperm_get(struct task_struct *target, */ void ptrace_disable(struct task_struct *child) { + child->ptrace &= ~(PT_SINGLE_STEP | PT_SINGLE_BLOCK); user_disable_single_step(child); #ifdef TIF_SYSCALL_EMU clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 98d995d..65b1e4f 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -91,6 +91,8 @@ #define PT_TRACE_MASK 0x000003f4 #define PT_SYSCALL_TRACE 0x00010000 +#define PT_SINGLE_STEP 0x00020000 +#define PT_SINGLE_BLOCK 0x00040000 /* single stepping state bits (used on ARM and PA-RISC) */ #define PT_SINGLESTEP_BIT 31 @@ -189,7 +191,8 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace) child->ptrace = 0; if (unlikely(ptrace) && (current->ptrace & PT_PTRACED)) { child->ptrace = current->ptrace; - child->ptrace &= ~PT_SYSCALL_TRACE; + child->ptrace &= + ~(PT_SYSCALL_TRACE | PT_SINGLE_STEP | PT_SINGLE_BLOCK); __ptrace_link(child, current->parent); } diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h index 6ce7a37..06edb52 100644 --- a/include/linux/tracehook.h +++ b/include/linux/tracehook.h @@ -121,6 +121,9 @@ static inline __must_check int tracehook_report_syscall_entry( return 0; } +#define ptrace_wants_step() \ + (current->ptrace & (PT_SINGLE_STEP | PT_SINGLE_BLOCK)) + /** * tracehook_report_syscall_exit - task has just finished a system call * @regs: user register state of current task @@ -143,7 +146,7 @@ static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step) if (task_utrace_flags(current) & UTRACE_EVENT(SYSCALL_EXIT)) utrace_report_syscall_exit(regs); - if (step) { + if (step && ptrace_wants_step()) { siginfo_t info; user_single_step_siginfo(current, regs, &info); force_sig_info(SIGTRAP, &info, current); @@ -436,7 +439,7 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, { if (task_utrace_flags(current)) utrace_signal_handler(current, stepping); - if (stepping) + if (stepping && ptrace_wants_step()) ptrace_notify(SIGTRAP); } diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 209ea2d..44908d0 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -575,13 +575,16 @@ static int ptrace_resume(struct task_struct *child, long request, clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); #endif + child->ptrace &= ~(PT_SINGLE_STEP | PT_SINGLE_BLOCK); if (is_singleblock(request)) { if (unlikely(!arch_has_block_step())) return -EIO; + child->ptrace |= PT_SINGLE_BLOCK; user_enable_block_step(child); } else if (is_singlestep(request) || is_sysemu_singlestep(request)) { if (unlikely(!arch_has_single_step())) return -EIO; + child->ptrace |= PT_SINGLE_STEP; user_enable_single_step(child); } else { user_disable_single_step(child); -- 1.5.5.1