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diff --git a/sys/dev/hwpmc/hwpmc_mod.c b/sys/dev/hwpmc/hwpmc_mod.c
--- a/sys/dev/hwpmc/hwpmc_mod.c
+++ b/sys/dev/hwpmc/hwpmc_mod.c
@@ -212,7 +212,6 @@
static int pmc_attach_one_process(struct proc *p, struct pmc *pm);
static int pmc_can_allocate_rowindex(struct proc *p, unsigned int ri,
int cpu);
-static int pmc_can_attach(struct pmc *pm, struct proc *p);
static void pmc_capture_user_callchain(int cpu, int soft,
struct trapframe *tf);
static void pmc_cleanup(void);
@@ -1029,61 +1028,6 @@
}
}
-/*
- * Check if PMC 'pm' may be attached to target process 't'.
- */
-
-static int
-pmc_can_attach(struct pmc *pm, struct proc *t)
-{
- struct proc *o; /* pmc owner */
- struct ucred *oc, *tc; /* owner, target credentials */
- int decline_attach, i;
-
- /*
- * A PMC's owner can always attach that PMC to itself.
- */
-
- if ((o = pm->pm_owner->po_owner) == t)
- return 0;
-
- PROC_LOCK(o);
- oc = o->p_ucred;
- crhold(oc);
- PROC_UNLOCK(o);
-
- PROC_LOCK(t);
- tc = t->p_ucred;
- crhold(tc);
- PROC_UNLOCK(t);
-
- /*
- * The effective uid of the PMC owner should match at least one
- * of the {effective,real,saved} uids of the target process.
- */
-
- decline_attach = oc->cr_uid != tc->cr_uid &&
- oc->cr_uid != tc->cr_svuid &&
- oc->cr_uid != tc->cr_ruid;
-
- /*
- * Every one of the target's group ids, must be in the owner's
- * group list.
- */
- for (i = 0; !decline_attach && i < tc->cr_ngroups; i++)
- decline_attach = !groupmember(tc->cr_groups[i], oc);
-
- /* check the read and saved gids too */
- if (decline_attach == 0)
- decline_attach = !groupmember(tc->cr_rgid, oc) ||
- !groupmember(tc->cr_svgid, oc);
-
- crfree(tc);
- crfree(oc);
-
- return !decline_attach;
-}
-
/*
* Attach a process to a PMC.
*/
@@ -1401,38 +1345,26 @@
if (freepath != NULL)
free(freepath, M_TEMP);
- PMCDBG4(PRC,EXC,1, "exec proc=%p (%d, %s) cred-changed=%d",
- p, p->p_pid, p->p_comm, pk->pm_credentialschanged);
-
- if (pk->pm_credentialschanged == 0) /* no change */
- return;
+ PMCDBG3(PRC,EXC,1, "exec proc=%p (%d, %s)", p, p->p_pid, p->p_comm);
/*
- * If the newly exec()'ed process has a different credential
- * than before, allow it to be the target of a PMC only if
- * the PMC's owner has sufficient privilege.
+ * For each PMC attached to the newly exec()'ed target process, the
+ * owning process must have sufficient privilege to re-attach. If the
+ * target process has different credentials than before the exec, or is
+ * otherwise not considered 'debuggable' by the owner in question (e.g.
+ * P2_NOTRACE is set for the process), then we may be forced to detach
+ * one or more PMCs.
+ *
+ * This is analogous to the call to p_candebug() in the
+ * PMC_OP_PMCATTACH path.
*/
for (ri = 0; ri < md->pmd_npmc; ri++) {
- if ((pm = pp->pp_pmcs[ri].pp_pmc) != NULL) {
- if (pmc_can_attach(pm, td->td_proc) != 0) {
- pmc_detach_one_process(td->td_proc, pm,
- PMC_FLAG_NONE);
- }
- }
- }
-
- KASSERT(pp->pp_refcnt >= 0 && pp->pp_refcnt <= md->pmd_npmc,
- ("[pmc,%d] Illegal ref count %u on pp %p", __LINE__,
- pp->pp_refcnt, pp));
+ if ((pm = pp->pp_pmcs[ri].pp_pmc) == NULL)
+ continue;
- /*
- * If this process is no longer the target of any
- * PMCs, we can remove the process entry and free
- * up space.
- */
- if (pp->pp_refcnt == 0) {
- pmc_remove_process_descriptor(pp);
- pmc_destroy_process_descriptor(pp);
+ po = pm->pm_owner;
+ if (p_candebug(FIRST_THREAD_IN_PROC(po->po_owner), p) != 0)
+ pmc_detach_one_process(p, pm, PMC_FLAG_REMOVE);
}
}
diff --git a/sys/kern/kern_exec.c b/sys/kern/kern_exec.c
--- a/sys/kern/kern_exec.c
+++ b/sys/kern/kern_exec.c
@@ -918,7 +918,6 @@
*/
if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
VOP_UNLOCK(imgp->vp);
- pe.pm_credentialschanged = credential_changing;
pe.pm_entryaddr = imgp->entry_addr;
PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
diff --git a/sys/sys/pmckern.h b/sys/sys/pmckern.h
--- a/sys/sys/pmckern.h
+++ b/sys/sys/pmckern.h
@@ -75,7 +75,6 @@
} ring_type_t;
struct pmckern_procexec {
- int pm_credentialschanged;
uintfptr_t pm_entryaddr;
};

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