[SPARC64]: Fix atomicity of TIF update in flush_thread()
Fix atomicity of TIF update in flush_thread() for sparc64 Fixes correctly the race by using *_ti_thread_flag. Race : parent process executing : sys_ptrace() (lock_kernel()) (ptrace_get_task_struct(pid)) arch_ptrace() ptrace_detach() ptrace_disable(child); clear_singlestep(child); clear_tsk_thread_flag(child, TIF_SINGLESTEP); (which clears the TIF_SINGLESTEP flag atomically from a different process) (put_task_struct(child)) (unlock_kernel()) And at the same time, in the child process : sys_execve() do_execve() search_binary_handler() load_elf_binary() flush_old_exec() flush_thread() doing a non-atomic thread flag update Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -413,8 +413,13 @@ void flush_thread(void)
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struct thread_info *t = current_thread_info();
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struct mm_struct *mm;
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if (t->flags & _TIF_ABI_PENDING)
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t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
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if (test_ti_thread_flag(t, TIF_ABI_PENDING)) {
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clear_ti_thread_flag(t, TIF_ABI_PENDING);
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if (test_ti_thread_flag(t, TIF_32BIT))
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clear_ti_thread_flag(t, TIF_32BIT);
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else
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set_ti_thread_flag(t, TIF_32BIT);
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}
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mm = t->task->mm;
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if (mm)
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