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Date:      Wed, 8 Jan 2020 16:57:08 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r356494 - head/sys/compat/linprocfs
Message-ID:  <202001081657.008Gv837056124@repo.freebsd.org>
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Author: markj
Date: Wed Jan  8 16:57:08 2020
New Revision: 356494
URL: https://svnweb.freebsd.org/changeset/base/356494

Log:
  linprocfs: Fix some bugs in the maps file implementation.
  
  - Export the offset into the backing object, not the object size.
  - Fix a bug where we would print the previous entry's "offset" when a
    map_entry has no object.
  - Try to identify shared mappings.  Linux prints "s" when the mapping
    "may be shared".  This attempt is not perfect, for example, we print
    "p" for anonymous memory that may be shared via
    minherit(INHERIT_SHARE).
  
  PR:		240992
  Reviewed by:	kib
  MFC after:	1 week
  MFC note:	no OBJ_ANON in stable/12
  Differential Revision:	https://reviews.freebsd.org/D23062

Modified:
  head/sys/compat/linprocfs/linprocfs.c

Modified: head/sys/compat/linprocfs/linprocfs.c
==============================================================================
--- head/sys/compat/linprocfs/linprocfs.c	Wed Jan  8 16:32:16 2020	(r356493)
+++ head/sys/compat/linprocfs/linprocfs.c	Wed Jan  8 16:57:08 2020	(r356494)
@@ -1146,7 +1146,7 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
 	vm_map_entry_t entry, tmp_entry;
 	vm_object_t obj, tobj, lobj;
 	vm_offset_t e_start, e_end;
-	vm_ooffset_t off = 0;
+	vm_ooffset_t off;
 	vm_prot_t e_prot;
 	unsigned int last_timestamp;
 	char *name = "", *freename = NULL;
@@ -1156,6 +1156,7 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
 	int error;
 	struct vnode *vp;
 	struct vattr vat;
+	bool private;
 
 	PROC_LOCK(p);
 	error = p_candebug(td, p);
@@ -1186,17 +1187,20 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
 		e_start = entry->start;
 		e_end = entry->end;
 		obj = entry->object.vm_object;
-		for (lobj = tobj = obj; tobj; tobj = tobj->backing_object) {
+		off = entry->offset;
+		for (lobj = tobj = obj; tobj != NULL;
+		    lobj = tobj, tobj = tobj->backing_object) {
 			VM_OBJECT_RLOCK(tobj);
+			off += lobj->backing_object_offset;
 			if (lobj != obj)
 				VM_OBJECT_RUNLOCK(lobj);
-			lobj = tobj;
 		}
+		private = (entry->eflags & MAP_ENTRY_COW) != 0 || obj == NULL ||
+		    (obj->flags & OBJ_ANON) != 0;
 		last_timestamp = map->timestamp;
 		vm_map_unlock_read(map);
 		ino = 0;
 		if (lobj) {
-			off = IDX_TO_OFF(lobj->size);
 			vp = vm_object_vnode(lobj);
 			if (vp != NULL)
 				vref(vp);
@@ -1233,7 +1237,7 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
 		    (e_prot & VM_PROT_READ)?"r":"-",
 		    (e_prot & VM_PROT_WRITE)?"w":"-",
 		    (e_prot & VM_PROT_EXECUTE)?"x":"-",
-		    "p",
+		    private ? "p" : "s",
 		    (u_long)off,
 		    0,
 		    0,

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