Assert that dtrace_probe() doesn't re-enter itself.
This helps catch cases where an instrumented function is called while in probe context. Submitted by: Domagoj Stolfa <domagoj.stolfa@gmail.com> MFC after: 2 weeks Sponsored by: DARPA/AFRL Differential Revision: https://reviews.freebsd.org/D14863
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391f888277
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8593136428
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=332364
@ -7256,6 +7256,44 @@ dtrace_store_by_ref(dtrace_difo_t *dp, caddr_t tomax, size_t size,
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*valoffsp = valoffs;
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}
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/*
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* Disables interrupts and sets the per-thread inprobe flag. When DEBUG is
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* defined, we also assert that we are not recursing unless the probe ID is an
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* error probe.
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*/
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static dtrace_icookie_t
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dtrace_probe_enter(dtrace_id_t id)
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{
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dtrace_icookie_t cookie;
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cookie = dtrace_interrupt_disable();
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/*
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* Unless this is an ERROR probe, we are not allowed to recurse in
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* dtrace_probe(). Recursing into DTrace probe usually means that a
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* function is instrumented that should not have been instrumented or
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* that the ordering guarantee of the records will be violated,
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* resulting in unexpected output. If there is an exception to this
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* assertion, a new case should be added.
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*/
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ASSERT(curthread->t_dtrace_inprobe == 0 ||
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id == dtrace_probeid_error);
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curthread->t_dtrace_inprobe = 1;
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return (cookie);
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}
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/*
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* Disables interrupts and clears the per-thread inprobe flag.
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*/
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static void
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dtrace_probe_exit(dtrace_icookie_t cookie)
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{
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curthread->t_dtrace_inprobe = 0;
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dtrace_interrupt_enable(cookie);
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}
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/*
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* If you're looking for the epicenter of DTrace, you just found it. This
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* is the function called by the provider to fire a probe -- from which all
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@ -7290,7 +7328,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t arg1,
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return;
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#endif
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cookie = dtrace_interrupt_disable();
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cookie = dtrace_probe_enter(id);
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probe = dtrace_probes[id - 1];
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cpuid = curcpu;
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onintr = CPU_ON_INTR(CPU);
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@ -7301,7 +7339,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t arg1,
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* We have hit in the predicate cache; we know that
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* this predicate would evaluate to be false.
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*/
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dtrace_interrupt_enable(cookie);
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dtrace_probe_exit(cookie);
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return;
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}
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@ -7313,7 +7351,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t arg1,
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/*
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* We don't trace anything if we're panicking.
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*/
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dtrace_interrupt_enable(cookie);
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dtrace_probe_exit(cookie);
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return;
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}
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@ -7939,7 +7977,7 @@ dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t arg1,
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if (vtime)
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curthread->t_dtrace_start = dtrace_gethrtime();
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dtrace_interrupt_enable(cookie);
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dtrace_probe_exit(cookie);
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}
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/*
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@ -46,6 +46,7 @@ typedef struct kdtrace_proc {
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typedef struct kdtrace_thread {
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u_int8_t td_dtrace_stop; /* Indicates a DTrace-desired stop */
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u_int8_t td_dtrace_sig; /* Signal sent via DTrace's raise() */
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u_int8_t td_dtrace_inprobe; /* Are we in a probe? */
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u_int td_predcache; /* DTrace predicate cache */
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u_int64_t td_dtrace_vtime; /* DTrace virtual time */
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u_int64_t td_dtrace_start; /* DTrace slice start time */
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@ -97,6 +98,7 @@ typedef struct kdtrace_thread {
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#define t_dtrace_start td_dtrace->td_dtrace_start
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#define t_dtrace_stop td_dtrace->td_dtrace_stop
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#define t_dtrace_sig td_dtrace->td_dtrace_sig
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#define t_dtrace_inprobe td_dtrace->td_dtrace_inprobe
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#define t_predcache td_dtrace->td_predcache
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#define t_dtrace_ft td_dtrace->td_dtrace_ft
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#define t_dtrace_on td_dtrace->td_dtrace_on
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