From e1f287735c1e58c653b516931b5d3dd899edcb77 Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Wed, 30 Jan 2008 13:30:50 +0100 Subject: x86 single_step: TIF_FORCED_TF This changes the single-step support to use a new thread_info flag TIF_FORCED_TF instead of the PT_DTRACE flag in task_struct.ptrace. This keeps arch implementation uses out of this non-arch field. This changes the ptrace access to eflags to mask TF and maintain the TIF_FORCED_TF flag directly if userland sets TF, instead of relying on ptrace_signal_deliver. The 64-bit and 32-bit kernels are harmonized on this same behavior. The ptrace_signal_deliver approach works now, but this change makes the low-level register access code reliable when called from different contexts than a ptrace stop, which will be possible in the future. The 64-bit do_debug exception handler is also changed not to clear TF from user-mode registers. This matches the 32-bit kernel's behavior. Signed-off-by: Roland McGrath Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/kernel/step.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) (limited to 'arch/x86/kernel/step.c') diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index 6732272e3479..243bff650ca5 100644 --- a/arch/x86/kernel/step.c +++ b/arch/x86/kernel/step.c @@ -135,7 +135,7 @@ void user_enable_single_step(struct task_struct *child) if (is_setting_trap_flag(child, regs)) return; - child->ptrace |= PT_DTRACE; + set_tsk_thread_flag(child, TIF_FORCED_TF); } void user_disable_single_step(struct task_struct *child) @@ -144,9 +144,6 @@ void user_disable_single_step(struct task_struct *child) 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 = task_pt_regs(child); - regs->eflags &= ~X86_EFLAGS_TF; - child->ptrace &= ~PT_DTRACE; - } + if (test_and_clear_tsk_thread_flag(child, TIF_FORCED_TF)) + task_pt_regs(child)->eflags &= ~X86_EFLAGS_TF; } -- cgit v1.2.3-59-g8ed1b