svn commit: r201021 - in head/sys: dev/hwpmc sys
Joseph Koshy
jkoshy at FreeBSD.org
Sat Dec 26 13:58:53 UTC 2009
Author: jkoshy
Date: Sat Dec 26 13:58:52 2009
New Revision: 201021
URL: http://svn.freebsd.org/changeset/base/201021
Log:
Log process mappings for existing processes at PMC start time.
Submitted by: Marc Unangst <mju at panasas dot com> [original patch]
Tested by: fabient
Modified:
head/sys/dev/hwpmc/hwpmc_mod.c
head/sys/sys/pmc.h
Modified: head/sys/dev/hwpmc/hwpmc_mod.c
==============================================================================
--- head/sys/dev/hwpmc/hwpmc_mod.c Sat Dec 26 13:54:34 2009 (r201020)
+++ head/sys/dev/hwpmc/hwpmc_mod.c Sat Dec 26 13:58:52 2009 (r201021)
@@ -63,6 +63,12 @@ __FBSDID("$FreeBSD$");
#include <machine/atomic.h>
#include <machine/md_var.h>
+#include <vm/vm.h>
+#include <vm/vm_extern.h>
+#include <vm/pmap.h>
+#include <vm/vm_map.h>
+#include <vm/vm_object.h>
+
/*
* Types
*/
@@ -1619,6 +1625,151 @@ pmc_log_kernel_mappings(struct pmc *pm)
static void
pmc_log_process_mappings(struct pmc_owner *po, struct proc *p)
{
+ vm_map_t map;
+ struct vnode *vp;
+ struct vmspace *vm;
+ vm_map_entry_t entry;
+ vm_offset_t last_end;
+ u_int last_timestamp;
+ struct vnode *last_vp;
+ vm_offset_t start_addr;
+ vm_object_t obj, lobj, tobj;
+ char *fullpath, *freepath;
+
+ last_vp = NULL;
+ last_end = (vm_offset_t) 0;
+ fullpath = freepath = NULL;
+
+ if ((vm = vmspace_acquire_ref(p)) == NULL)
+ return;
+
+ map = &vm->vm_map;
+ vm_map_lock_read(map);
+
+ for (entry = map->header.next; entry != &map->header; entry = entry->next) {
+
+ if (entry == NULL) {
+ PMCDBG(LOG,OPS,2, "hwpmc: vm_map entry unexpectedly "
+ "NULL! pid=%d vm_map=%p\n", p->p_pid, map);
+ break;
+ }
+
+ /*
+ * We only care about executable map entries.
+ */
+ if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) ||
+ !(entry->protection & VM_PROT_EXECUTE) ||
+ (entry->object.vm_object == NULL)) {
+ continue;
+ }
+
+ obj = entry->object.vm_object;
+ VM_OBJECT_LOCK(obj);
+
+ /*
+ * Walk the backing_object list to find the base
+ * (non-shadowed) vm_object.
+ */
+ for (lobj = tobj = obj; tobj != NULL; tobj = tobj->backing_object) {
+ if (tobj != obj)
+ VM_OBJECT_LOCK(tobj);
+ if (lobj != obj)
+ VM_OBJECT_UNLOCK(lobj);
+ lobj = tobj;
+ }
+
+ /*
+ * At this point lobj is the base vm_object and it is locked.
+ */
+ if (lobj == NULL) {
+ PMCDBG(LOG,OPS,2, "hwpmc: lobj unexpectedly NULL! pid=%d "
+ "vm_map=%p vm_obj=%p\n", p->p_pid, map, obj);
+ VM_OBJECT_UNLOCK(obj);
+ continue;
+ }
+
+ if (lobj->type != OBJT_VNODE || lobj->handle == NULL) {
+ if (lobj != obj)
+ VM_OBJECT_UNLOCK(lobj);
+ VM_OBJECT_UNLOCK(obj);
+ continue;
+ }
+
+ /*
+ * Skip contiguous regions that point to the same
+ * vnode, so we don't emit redundant MAP-IN
+ * directives.
+ */
+ if (entry->start == last_end && lobj->handle == last_vp) {
+ last_end = entry->end;
+ if (lobj != obj)
+ VM_OBJECT_UNLOCK(lobj);
+ VM_OBJECT_UNLOCK(obj);
+ continue;
+ }
+
+ /*
+ * We don't want to keep the proc's vm_map or this
+ * vm_object locked while we walk the pathname, since
+ * vn_fullpath() can sleep. However, if we drop the
+ * lock, it's possible for concurrent activity to
+ * modify the vm_map list. To protect against this,
+ * we save the vm_map timestamp before we release the
+ * lock, and check it after we reacquire the lock
+ * below.
+ */
+ start_addr = entry->start;
+ last_end = entry->end;
+ last_timestamp = map->timestamp;
+ vm_map_unlock_read(map);
+
+ vp = lobj->handle;
+ vref(vp);
+ if (lobj != obj)
+ VM_OBJECT_UNLOCK(lobj);
+
+ VM_OBJECT_UNLOCK(obj);
+
+ freepath = NULL;
+ pmc_getfilename(vp, &fullpath, &freepath);
+ last_vp = vp;
+ vrele(vp);
+ vp = NULL;
+ pmclog_process_map_in(po, p->p_pid, start_addr, fullpath);
+ if (freepath)
+ free(freepath, M_TEMP);
+
+ vm_map_lock_read(map);
+
+ /*
+ * If our saved timestamp doesn't match, this means
+ * that the vm_map was modified out from under us and
+ * we can't trust our current "entry" pointer. Do a
+ * new lookup for this entry. If there is no entry
+ * for this address range, vm_map_lookup_entry() will
+ * return the previous one, so we always want to go to
+ * entry->next on the next loop iteration.
+ *
+ * There is an edge condition here that can occur if
+ * there is no entry at or before this address. In
+ * this situation, vm_map_lookup_entry returns
+ * &map->header, which would cause our loop to abort
+ * without processing the rest of the map. However,
+ * in practice this will never happen for process
+ * vm_map. This is because the executable's text
+ * segment is the first mapping in the proc's address
+ * space, and this mapping is never removed until the
+ * process exits, so there will always be a non-header
+ * entry at or before the requested address for
+ * vm_map_lookup_entry to return.
+ */
+ if (map->timestamp != last_timestamp)
+ vm_map_lookup_entry(map, last_end - 1, &entry);
+ }
+
+ vm_map_unlock_read(map);
+ vmspace_free(vm);
+ return;
}
/*
@@ -1897,7 +2048,7 @@ pmc_allocate_owner_descriptor(struct pro
/* allocate space for N pointers and one descriptor struct */
po = malloc(sizeof(struct pmc_owner), M_PMC, M_WAITOK|M_ZERO);
- po->po_sscount = po->po_error = po->po_flags = 0;
+ po->po_sscount = po->po_error = po->po_flags = po->po_logprocmaps = 0;
po->po_file = NULL;
po->po_owner = p;
po->po_kthread = NULL;
@@ -2520,8 +2671,15 @@ pmc_start(struct pmc *pm)
po->po_sscount++;
}
- /* Log mapping information for all processes in the system. */
- pmc_log_all_process_mappings(po);
+ /*
+ * Log mapping information for all existing processes in the
+ * system. Subsequent mappings are logged as they happen;
+ * see pmc_process_mmap().
+ */
+ if (po->po_logprocmaps == 0) {
+ pmc_log_all_process_mappings(po);
+ po->po_logprocmaps = 1;
+ }
/*
* Move to the CPU associated with this
Modified: head/sys/sys/pmc.h
==============================================================================
--- head/sys/sys/pmc.h Sat Dec 26 13:54:34 2009 (r201020)
+++ head/sys/sys/pmc.h Sat Dec 26 13:58:52 2009 (r201021)
@@ -752,7 +752,8 @@ struct pmc_owner {
struct pmclog_buffer *po_curbuf; /* current log buffer */
struct file *po_file; /* file reference */
int po_error; /* recorded error */
- int po_sscount; /* # SS PMCs owned */
+ short po_sscount; /* # SS PMCs owned */
+ short po_logprocmaps; /* global mappings done */
};
#define PMC_PO_OWNS_LOGFILE 0x00000001 /* has a log file */
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