svn commit: r327561 - head/sys/kern

[John Baldwin]

Author: jhb
Date: Thu Jan  4 21:59:34 2018
New Revision: 327561
URL: https://svnweb.freebsd.org/changeset/base/327561

Log:
  Report offset relative to the backing object for kinfo_vmentry structures.
  
  For the pathname reported in kinfo_vmentry structures (kve_path), the
  sysctl handlers walk the object chain to find the bottom-most VM object.
  This permits a COW mapping of a file with dirty pages to report the
  pathname of the originally mapped file.  Do the same for the object
  offset (kve_offset) computing a cumulative offset during the same object
  walk so that the reported offset is relative to the reported pathname.
  
  Note that ptrace(PT_VM_ENTRY) already returns a cumulative offset
  rather than the raw offset of the VM map entry.
  
  Note also that this does not affect procstat -v output (even structured
  output) since that output does not include the kve_offset field.
  
  Reviewed by:	kib
  MFC after:	2 weeks
  Sponsored by:	DARPA / AFRL
  Differential Revision:	https://reviews.freebsd.org/D13767

Modified:
  head/sys/kern/kern_proc.c

Modified: head/sys/kern/kern_proc.c
==============================================================================
--- head/sys/kern/kern_proc.c	Thu Jan  4 21:57:37 2018	(r327560)
+++ head/sys/kern/kern_proc.c	Thu Jan  4 21:59:34 2018	(r327561)
@@ -2159,8 +2159,10 @@ sysctl_kern_proc_ovmmap(SYSCTL_HANDLER_ARGS)
 		}
 
 		for (lobj = tobj = obj; tobj; tobj = tobj->backing_object) {
-			if (tobj != obj)
+			if (tobj != obj) {
 				VM_OBJECT_RLOCK(tobj);
+				kve->kve_offset += tobj->backing_object_offset;
+			}
 			if (lobj != obj)
 				VM_OBJECT_RUNLOCK(lobj);
 			lobj = tobj;
@@ -2168,7 +2170,7 @@ sysctl_kern_proc_ovmmap(SYSCTL_HANDLER_ARGS)
 
 		kve->kve_start = (void*)entry->start;
 		kve->kve_end = (void*)entry->end;
-		kve->kve_offset = (off_t)entry->offset;
+		kve->kve_offset += (off_t)entry->offset;
 
 		if (entry->protection & VM_PROT_READ)
 			kve->kve_protection |= KVME_PROT_READ;
@@ -2389,6 +2391,7 @@ kern_proc_vmmap_out(struct proc *p, struct sbuf *sb, s
 			for (tobj = obj; tobj != NULL;
 			    tobj = tobj->backing_object) {
 				VM_OBJECT_RLOCK(tobj);
+				kve->kve_offset += tobj->backing_object_offset;
 				lobj = tobj;
 			}
 			if (obj->backing_object == NULL)
@@ -2409,7 +2412,7 @@ kern_proc_vmmap_out(struct proc *p, struct sbuf *sb, s
 
 		kve->kve_start = entry->start;
 		kve->kve_end = entry->end;
-		kve->kve_offset = entry->offset;
+		kve->kve_offset += entry->offset;
 
 		if (entry->protection & VM_PROT_READ)
 			kve->kve_protection |= KVME_PROT_READ;