Messages in this thread Patch in this message | | | Date | Mon, 23 Mar 2020 23:00:25 +0900 | From | Masami Hiramatsu <> | Subject | Re: [patch V3 04/23] kprobes: Prevent probes in .noinstr.text section |
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Hi Thomas,
On Fri, 20 Mar 2020 19:00:00 +0100 Thomas Gleixner <tglx@linutronix.de> wrote:
> Instrumentation is forbidden in the .noinstr.text section. Make kprobes > respect this. > > This lacks support for .noinstr.text sections in modules, which is required > to handle VMX and SVM. >
Would you have any plan to list or mark the noinstr symbols on some debugfs interface? I need a blacklist of those symbols so that user (and perf-probe) can check which function can not be probed.
It is just calling kprobe_add_area_blacklist() like below.
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 2625c241ac00..4835b644bd2b 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2212,6 +2212,10 @@ static int __init populate_kprobe_blacklist(unsigned long *start, ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start, (unsigned long)__kprobes_text_end); + /* Symbols in noinstr section are blacklisted */ + ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start, + (unsigned long)__noinstr_text_end); + return ret ? : arch_populate_kprobe_blacklist(); } Thank you,
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > kernel/kprobes.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1443,10 +1443,21 @@ static bool __within_kprobe_blacklist(un > return false; > } > > +/* Functions in .noinstr.text must not be probed */ > +static bool within_noinstr_text(unsigned long addr) > +{ > + /* FIXME: Handle module .noinstr.text */ > + return addr >= (unsigned long)__noinstr_text_start && > + addr < (unsigned long)__noinstr_text_end; > +} > + > bool within_kprobe_blacklist(unsigned long addr) > { > char symname[KSYM_NAME_LEN], *p; > > + if (within_noinstr_text(addr)) > + return true; > + > if (__within_kprobe_blacklist(addr)) > return true; > >
-- Masami Hiramatsu <mhiramat@kernel.org>
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