Messages in this thread | | | Date | Mon, 27 Jul 2020 13:21:44 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] objtool,x86: Verify poke_int3_handler() is self contained |
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* peterz@infradead.org <peterz@infradead.org> wrote:
> > Abuse the SMAP rules to ensure poke_int3_handler() doesn't call out to > anything. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > tools/objtool/check.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > --- a/tools/objtool/check.c > +++ b/tools/objtool/check.c > @@ -551,6 +551,14 @@ static const char *uaccess_safe_builtin[ > "__memcpy_mcsafe", > "mcsafe_handle_tail", > "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ > + /* > + * Abuse alert! > + * > + * poke_int3_handler() is not in fact related to uaccess at all, we > + * abuse the uaccess rules to ensure poke_int3_handler() is self > + * contained and doesn't CALL out to other code. > + */ > + "poke_int3_handler",
So ->uaccess_safe makes sure that we don't CALL into non-uaccess-safe functions, but it still allows CALLs into *other* uaccess-safe functions, right?
So unless I missed something in the logic, the comment should say something like "doesn't CALL out to other non-uaccess safe code" or so? Which is, arguably, like 99% of all functions - but still, a whole bunch are allowed, such as low level instrumentation and other utility functions.
Thanks,
Ingo
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