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Define a vm_map method for user-space for advancing from a map entry

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to its successor in cases where examining a map entry requires a
helper like kvm_read_all.  Use that method, with kvm_read_all, to fix
procstat_getfiles_kvm, which tries to find the successor now without
using such a helper.  This addresses a problem introduced by r355491.

Reviewed by: markj (previous version)
Discussed with: kib
Differential Revision: https://reviews.freebsd.org/D22728
This commit is contained in:
Doug Moore 2019-12-08 22:33:51 +00:00
parent abd80ddb94
commit 8b75b1ad0d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=355538
2 changed files with 56 additions and 11 deletions
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26
lib/libprocstat/libprocstat.c
View File

@ -445,6 +445,15 @@ getctty(kvm_t *kd, struct kinfo_proc *kp)
return (sess.s_ttyvp);
}
static int
procstat_vm_map_reader(void *token, vm_map_entry_t addr, vm_map_entry_t dest)
{
kvm_t *kd;
kd = (kvm_t *)token;
return (kvm_read_all(kd, (unsigned long)addr, dest, sizeof(*dest)));
}
static struct filestat_list *
procstat_getfiles_kvm(struct procstat *procstat, struct kinfo_proc *kp, int mmapped)
{
@ -454,7 +463,6 @@ procstat_getfiles_kvm(struct procstat *procstat, struct kinfo_proc *kp, int mmap
struct vm_object object;
struct vmspace vmspace;
vm_map_entry_t entryp;
vm_map_t map;
vm_object_t objp;
struct vnode *vp;
struct file **ofiles;
@ -615,17 +623,11 @@ procstat_getfiles_kvm(struct procstat *procstat, struct kinfo_proc *kp, int mmap
(void *)kp->ki_vmspace);
goto exit;
}
map = &vmspace.vm_map;
for (entryp = vm_map_entry_first(map);
entryp != &kp->ki_vmspace->vm_map.header;
entryp = vm_map_entry_succ(&vmentry)) {
if (!kvm_read_all(kd, (unsigned long)entryp, &vmentry,
sizeof(vmentry))) {
warnx("can't read vm_map_entry at %p",
(void *)entryp);
continue;
}
vmentry = vmspace.vm_map.header;
for (entryp = vm_map_entry_read_succ(kd, &vmentry, procstat_vm_map_reader);
entryp != NULL && entryp != &kp->ki_vmspace->vm_map.header;
entryp = vm_map_entry_read_succ(kd, &vmentry, procstat_vm_map_reader)) {
if (vmentry.eflags & MAP_ENTRY_IS_SUB_MAP)
continue;
if ((objp = vmentry.object.vm_object) == NULL)
@ -660,6 +662,8 @@ procstat_getfiles_kvm(struct procstat *procstat, struct kinfo_proc *kp, int mmap
if (entry != NULL)
STAILQ_INSERT_TAIL(head, entry, next);
}
if (entryp == NULL)
warnx("can't read vm_map_entry");
}
exit:
return (head);

41
sys/vm/vm_map.h
View File

@ -402,6 +402,47 @@ long vmspace_resident_count(struct vmspace *vmspace);
#define VM_MAP_WIRE_WRITE 4 /* Validate writable. */
typedef int vm_map_entry_reader(void *token, vm_map_entry_t addr,
vm_map_entry_t dest);
#ifndef _KERNEL
/*
* Find the successor of a map_entry, using a reader to dereference pointers.
* '*clone' is a copy of a vm_map entry. 'reader' is used to copy a map entry
* at some address into '*clone'. Change *clone to a copy of the next map
* entry, and return the address of that entry, or NULL if copying has failed.
*
* This function is made available to user-space code that needs to traverse
* map entries.
*/
static inline vm_map_entry_t
vm_map_entry_read_succ(void *token, struct vm_map_entry *const clone,
vm_map_entry_reader reader)
{
vm_map_entry_t after, backup;
vm_offset_t start;
after = clone->right;
start = clone->start;
if (!reader(token, after, clone))
return (NULL);
backup = clone->left;
if (!reader(token, backup, clone))
return (NULL);
if (clone->start > start) {
do {
after = backup;
backup = clone->left;
if (!reader(token, backup, clone))
return (NULL);
} while (clone->start != start);
}
if (!reader(token, after, clone))
return (NULL);
return (after);
}
#endif /* ! _KERNEL */
static inline vm_map_entry_t
vm_map_entry_first(vm_map_t map)
{