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x86/uaccess: Don't leak AC flag into fentry from mcsafe_handle_tail()
After adding mcsafe_handle_tail() to the objtool uaccess safe list, objtool reports: arch/x86/lib/usercopy_64.o: warning: objtool: mcsafe_handle_tail()+0x0: call to __fentry__() with UACCESS enabled With SMAP, this function is called with AC=1, so it needs to be careful about which functions it calls. Disable the ftrace entry hook, which can potentially pull in a lot of extra code. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/8e13d6f0da1c8a3f7603903da6cbf6d582bbfe10.1563413318.git.jpoimboe@redhat.com
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@ -60,7 +60,7 @@ EXPORT_SYMBOL(clear_user);
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* but reuse __memcpy_mcsafe in case a new read error is encountered.
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* clac() is handled in _copy_to_iter_mcsafe().
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*/
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__visible unsigned long
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__visible notrace unsigned long
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mcsafe_handle_tail(char *to, char *from, unsigned len)
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{
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for (; len; --len, to++, from++) {
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