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-rw-r--r--arch/x86/kernel/ptrace_32.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/x86/kernel/ptrace_32.c b/arch/x86/kernel/ptrace_32.c
index b739608..bc7fd80 100644
--- a/arch/x86/kernel/ptrace_32.c
+++ b/arch/x86/kernel/ptrace_32.c
@@ -104,6 +104,15 @@ static int putreg(struct task_struct *child,
break;
case EFL:
value &= FLAG_MASK;
+ /*
+ * If the user value contains TF, mark that
+ * it was not "us" (the debugger) that set it.
+ * If not, make sure it stays set if we had.
+ */
+ if (value & X86_EFLAGS_TF)
+ clear_tsk_thread_flag(child, TIF_FORCED_TF);
+ else if (test_tsk_thread_flag(child, TIF_FORCED_TF))
+ value |= X86_EFLAGS_TF;
value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK;
break;
}
@@ -119,6 +128,14 @@ static unsigned long getreg(struct task_struct *child,
unsigned long retval = ~0UL;
switch (regno >> 2) {
+ case EFL:
+ /*
+ * If the debugger set TF, hide it from the readout.
+ */
+ retval = get_stack_long(child, EFL_OFFSET);
+ if (test_tsk_thread_flag(child, TIF_FORCED_TF))
+ retval &= ~X86_EFLAGS_TF;
+ break;
case GS:
retval = child->thread.gs;
break;
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