From aa85b9af5bdae1f8b84d80367324e4410c3f0674 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Sat, 16 Apr 2005 15:24:56 -0700 Subject: [PATCH] [PATCH] x86_64: clean up ptrace single-stepping Ported from i386 (originally from Linus) clean up ptrace single-stepping, make PT_DTRACE exact. (This makes the naming of "DTRACE" purely historical, since on x86 it now means "single step in progress"). Signed-off-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/ptrace.c | 79 +++++++++++++++++++++++-------------- 1 file changed, 50 insertions(+), 29 deletions(-) diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c index 0b7b101deb..002237c3b6 100644 --- a/arch/x86_64/kernel/ptrace.c +++ b/arch/x86_64/kernel/ptrace.c @@ -63,6 +63,12 @@ static inline unsigned long get_stack_long(struct task_struct *task, int offset) return (*((unsigned long *)stack)); } +static inline struct pt_regs *get_child_regs(struct task_struct *task) +{ + struct pt_regs *regs = (void *)task->thread.rsp0; + return regs - 1; +} + /* * this routine will put a word on the processes privileged stack. * the offset is how far from the base addr as stored in the TSS. @@ -80,6 +86,42 @@ static inline long put_stack_long(struct task_struct *task, int offset, return 0; } +static void set_singlestep(struct task_struct *child) +{ + struct pt_regs *regs = get_child_regs(child); + + /* + * Always set TIF_SINGLESTEP - this guarantees that + * we single-step system calls etc.. This will also + * cause us to set TF when returning to user mode. + */ + set_tsk_thread_flag(child, TIF_SINGLESTEP); + + /* + * If TF was already set, don't do anything else + */ + if (regs->eflags & TRAP_FLAG) + return; + + /* Set TF on the kernel stack.. */ + regs->eflags |= TRAP_FLAG; + + child->ptrace |= PT_DTRACE; +} + +static void clear_singlestep(struct task_struct *child) +{ + /* Always clear TIF_SINGLESTEP... */ + clear_tsk_thread_flag(child, TIF_SINGLESTEP); + + /* But touch TF only if it was set by us.. */ + if (child->ptrace & PT_DTRACE) { + struct pt_regs *regs = get_child_regs(child); + regs->eflags &= ~TRAP_FLAG; + child->ptrace &= ~PT_DTRACE; + } +} + /* * Called by kernel/ptrace.c when detaching.. * @@ -87,11 +129,7 @@ static inline long put_stack_long(struct task_struct *task, int offset, */ void ptrace_disable(struct task_struct *child) { - long tmp; - - clear_tsk_thread_flag(child, TIF_SINGLESTEP); - tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG; - put_stack_long(child, EFL_OFFSET, tmp); + clear_singlestep(child); } static int putreg(struct task_struct *child, @@ -338,8 +376,7 @@ asmlinkage long sys_ptrace(long request, long pid, unsigned long addr, long data } break; case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */ - case PTRACE_CONT: { /* restart after signal. */ - long tmp; + case PTRACE_CONT: /* restart after signal. */ ret = -EIO; if ((unsigned long) data > _NSIG) @@ -350,14 +387,11 @@ asmlinkage long sys_ptrace(long request, long pid, unsigned long addr, long data clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE); clear_tsk_thread_flag(child, TIF_SINGLESTEP); child->exit_code = data; - /* make sure the single step bit is not set. */ - tmp = get_stack_long(child, EFL_OFFSET); - tmp &= ~TRAP_FLAG; - put_stack_long(child, EFL_OFFSET,tmp); + /* make sure the single step bit is not set. */ + clear_singlestep(child); wake_up_process(child); ret = 0; break; - } #ifdef CONFIG_IA32_EMULATION /* This makes only sense with 32bit programs. Allow a @@ -394,41 +428,28 @@ asmlinkage long sys_ptrace(long request, long pid, unsigned long addr, long data * perhaps it should be put in the status that it wants to * exit. */ - case PTRACE_KILL: { - long tmp; - + case PTRACE_KILL: ret = 0; if (child->exit_state == EXIT_ZOMBIE) /* already dead */ break; clear_tsk_thread_flag(child, TIF_SINGLESTEP); child->exit_code = SIGKILL; /* make sure the single step bit is not set. */ - tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG; - put_stack_long(child, EFL_OFFSET, tmp); + clear_singlestep(child); wake_up_process(child); break; - } - - case PTRACE_SINGLESTEP: { /* set the trap flag. */ - long tmp; + case PTRACE_SINGLESTEP: /* set the trap flag. */ ret = -EIO; if ((unsigned long) data > _NSIG) break; clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE); - if ((child->ptrace & PT_DTRACE) == 0) { - /* Spurious delayed TF traps may occur */ - child->ptrace |= PT_DTRACE; - } - tmp = get_stack_long(child, EFL_OFFSET) | TRAP_FLAG; - put_stack_long(child, EFL_OFFSET, tmp); - set_tsk_thread_flag(child, TIF_SINGLESTEP); + set_singlestep(child); child->exit_code = data; /* give it a chance to run. */ wake_up_process(child); ret = 0; break; - } case PTRACE_DETACH: /* detach a process that was attached. */ -- 2.39.5