[PATCH] NOMMU: Implement /proc/pid/maps for NOMMU

Implement /proc/pid/maps for NOMMU by reading the vm_area_list attached to current->mm->context.vmlist. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] NOMMU: Implement /proc/pid/maps for NOMMU
Implement /proc/pid/maps for NOMMU by reading the vm_area_list attached to current->mm->context.vmlist. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
David Howells · Linus Torvalds
1 parent d00c7b9937
Showing 5 changed files with 80 additions and 20 deletions Side-by-side Diff
Documentation/nommu-mmap.txt
fs/proc/internal.h
fs/proc/nommu.c
fs/proc/task_nommu.c
include/linux/proc_fs.h
@@ -116,6 +116,9 @@
  (*) A list of all the mappings on the system is visible through /proc/maps in
      no-MMU mode.
  
+ (*) A list of all the mappings in use by a process is visible through
+     /proc/<pid>/maps in no-MMU mode.
+
  (*) Supplying MAP_FIXED or a requesting a particular mapping address will
      result in an error.
  
@@ -28,6 +28,7 @@
 	(vmi)->largest_chunk = 0;		\
 } while(0)
  
+extern int nommu_vma_show(struct seq_file *, struct vm_area_struct *);
 #endif
  
 extern void create_seq_entry(char *name, mode_t mode, const struct file_operations *f);
@@ -33,19 +33,15 @@
 #include "internal.h"
  
 /*
- * display a list of all the VMAs the kernel knows about
- * - nommu kernals have a single flat list
+ * display a single VMA to a sequenced file
  */
-static int nommu_vma_list_show(struct seq_file *m, void *v)
+int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
 {
-	struct vm_area_struct *vma;
 	unsigned long ino = 0;
 	struct file *file;
 	dev_t dev = 0;
 	int flags, len;
  
-	vma = rb_entry((struct rb_node *) v, struct vm_area_struct, vm_rb);
-
 	flags = vma->vm_flags;
 	file = vma->vm_file;
  
@@ -76,6 +72,18 @@
  
 	seq_putc(m, '\n');
 	return 0;
+}
+
+/*
+ * display a list of all the VMAs the kernel knows about
+ * - nommu kernals have a single flat list
+ */
+static int nommu_vma_list_show(struct seq_file *m, void *v)
+{
+	struct vm_area_struct *vma;
+
+	vma = rb_entry((struct rb_node *) v, struct vm_area_struct, vm_rb);
+	return nommu_vma_show(m, vma);
 }
  
 static void *nommu_vma_list_start(struct seq_file *m, loff_t *_pos)
@@ -138,25 +138,63 @@
 }
  
 /*
- * Albert D. Cahalan suggested to fake entries for the traditional
- * sections here.  This might be worth investigating.
+ * display mapping lines for a particular process's /proc/pid/maps
  */
-static int show_map(struct seq_file *m, void *v)
+static int show_map(struct seq_file *m, void *_vml)
 {
-	return 0;
+	struct vm_list_struct *vml = _vml;
+	return nommu_vma_show(m, vml->vma);
 }
+
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
+	struct proc_maps_private *priv = m->private;
+	struct vm_list_struct *vml;
+	struct mm_struct *mm;
+	loff_t n = *pos;
+
+	/* pin the task and mm whilst we play with them */
+	priv->task = get_pid_task(priv->pid, PIDTYPE_PID);
+	if (!priv->task)
+		return NULL;
+
+	mm = get_task_mm(priv->task);
+	if (!mm) {
+		put_task_struct(priv->task);
+		priv->task = NULL;
+		return NULL;
+	}
+
+	down_read(&mm->mmap_sem);
+
+	/* start from the Nth VMA */
+	for (vml = mm->context.vmlist; vml; vml = vml->next)
+		if (n-- == 0)
+			return vml;
 	return NULL;
 }
-static void m_stop(struct seq_file *m, void *v)
+
+static void m_stop(struct seq_file *m, void *_vml)
 {
+	struct proc_maps_private *priv = m->private;
+
+	if (priv->task) {
+		struct mm_struct *mm = priv->task->mm;
+		up_read(&mm->mmap_sem);
+		mmput(mm);
+		put_task_struct(priv->task);
+	}
 }
-static void *m_next(struct seq_file *m, void *v, loff_t *pos)
+
+static void *m_next(struct seq_file *m, void *_vml, loff_t *pos)
 {
-	return NULL;
+	struct vm_list_struct *vml = _vml;
+
+	(*pos)++;
+	return vml ? vml->next : NULL;
 }
-static struct seq_operations proc_pid_maps_op = {
+
+static struct seq_operations proc_pid_maps_ops = {
 	.start	= m_start,
 	.next	= m_next,
 	.stop	= m_stop,
@@ -165,11 +203,19 @@
  
 static int maps_open(struct inode *inode, struct file *file)
 {
-	int ret;
-	ret = seq_open(file, &proc_pid_maps_op);
-	if (!ret) {
-		struct seq_file *m = file->private_data;
-		m->private = NULL;
+	struct proc_maps_private *priv;
+	int ret = -ENOMEM;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (priv) {
+		priv->pid = proc_pid(inode);
+		ret = seq_open(file, &proc_pid_maps_ops);
+		if (!ret) {
+			struct seq_file *m = file->private_data;
+			m->private = priv;
+		} else {
+			kfree(priv);
+		}
 	}
 	return ret;
 }
@@ -178,6 +224,6 @@
 	.open		= maps_open,
 	.read		= seq_read,
 	.llseek		= seq_lseek,
-	.release	= seq_release,
+	.release	= seq_release_private,
 };
@@ -268,7 +268,9 @@
 struct proc_maps_private {
 	struct pid *pid;
 	struct task_struct *task;
+#ifdef CONFIG_MMU
 	struct vm_area_struct *tail_vma;
+#endif
 };
  
 #endif /* _LINUX_PROC_FS_H */
...	...	@@ -116,6 +116,9 @@
116	116	(*) A list of all the mappings on the system is visible through /proc/maps in
117	117	no-MMU mode.
118	118
	119	+ (*) A list of all the mappings in use by a process is visible through
	120	+ /proc/<pid>/maps in no-MMU mode.
	121	+
119	122	(*) Supplying MAP_FIXED or a requesting a particular mapping address will
120	123	result in an error.
121	124
...	...	@@ -28,6 +28,7 @@
28	28	(vmi)->largest_chunk = 0; \
29	29	} while(0)
30	30
	31	+extern int nommu_vma_show(struct seq_file , struct vm_area_struct );
31	32	#endif
32	33
33	34	extern void create_seq_entry(char name, mode_t mode, const struct file_operations f);
...	...	@@ -33,19 +33,15 @@
33	33	#include "internal.h"
34	34
35	35	/*
36		- * display a list of all the VMAs the kernel knows about
37		- * - nommu kernals have a single flat list
	36	+ * display a single VMA to a sequenced file
38	37	*/
39		-static int nommu_vma_list_show(struct seq_file m, void v)
	38	+int nommu_vma_show(struct seq_file m, struct vm_area_struct vma)
40	39	{
41		- struct vm_area_struct *vma;
42	40	unsigned long ino = 0;
43	41	struct file *file;
44	42	dev_t dev = 0;
45	43	int flags, len;
46	44
47		- vma = rb_entry((struct rb_node *) v, struct vm_area_struct, vm_rb);
48		-
49	45	flags = vma->vm_flags;
50	46	file = vma->vm_file;
51	47
...	...	@@ -76,6 +72,18 @@
76	72
77	73	seq_putc(m, '\n');
78	74	return 0;
	75	+}
	76	+
	77	+/*
	78	+ * display a list of all the VMAs the kernel knows about
	79	+ * - nommu kernals have a single flat list
	80	+ */
	81	+static int nommu_vma_list_show(struct seq_file m, void v)
	82	+{
	83	+ struct vm_area_struct *vma;
	84	+
	85	+ vma = rb_entry((struct rb_node *) v, struct vm_area_struct, vm_rb);
	86	+ return nommu_vma_show(m, vma);
79	87	}
80	88
81	89	static void nommu_vma_list_start(struct seq_file m, loff_t *_pos)
...	...	@@ -138,25 +138,63 @@
138	138	}
139	139
140	140	/*
141		- * Albert D. Cahalan suggested to fake entries for the traditional
142		- * sections here. This might be worth investigating.
	141	+ * display mapping lines for a particular process's /proc/pid/maps
143	142	*/
144		-static int show_map(struct seq_file m, void v)
	143	+static int show_map(struct seq_file m, void _vml)
145	144	{
146		- return 0;
	145	+ struct vm_list_struct *vml = _vml;
	146	+ return nommu_vma_show(m, vml->vma);
147	147	}
	148	+
148	149	static void m_start(struct seq_file m, loff_t *pos)
149	150	{
	151	+ struct proc_maps_private *priv = m->private;
	152	+ struct vm_list_struct *vml;
	153	+ struct mm_struct *mm;
	154	+ loff_t n = *pos;
	155	+
	156	+ /* pin the task and mm whilst we play with them */
	157	+ priv->task = get_pid_task(priv->pid, PIDTYPE_PID);
	158	+ if (!priv->task)
	159	+ return NULL;
	160	+
	161	+ mm = get_task_mm(priv->task);
	162	+ if (!mm) {
	163	+ put_task_struct(priv->task);
	164	+ priv->task = NULL;
	165	+ return NULL;
	166	+ }
	167	+
	168	+ down_read(&mm->mmap_sem);
	169	+
	170	+ /* start from the Nth VMA */
	171	+ for (vml = mm->context.vmlist; vml; vml = vml->next)
	172	+ if (n-- == 0)
	173	+ return vml;
150	174	return NULL;
151	175	}
152		-static void m_stop(struct seq_file m, void v)
	176	+
	177	+static void m_stop(struct seq_file m, void _vml)
153	178	{
	179	+ struct proc_maps_private *priv = m->private;
	180	+
	181	+ if (priv->task) {
	182	+ struct mm_struct *mm = priv->task->mm;
	183	+ up_read(&mm->mmap_sem);
	184	+ mmput(mm);
	185	+ put_task_struct(priv->task);
	186	+ }
154	187	}
155		-static void m_next(struct seq_file m, void v, loff_t pos)
	188	+
	189	+static void m_next(struct seq_file m, void _vml, loff_t pos)
156	190	{
157		- return NULL;
	191	+ struct vm_list_struct *vml = _vml;
	192	+
	193	+ (*pos)++;
	194	+ return vml ? vml->next : NULL;
158	195	}
159		-static struct seq_operations proc_pid_maps_op = {
	196	+
	197	+static struct seq_operations proc_pid_maps_ops = {
160	198	.start = m_start,
161	199	.next = m_next,
162	200	.stop = m_stop,
...	...	@@ -165,11 +203,19 @@
165	203
166	204	static int maps_open(struct inode inode, struct file file)
167	205	{
168		- int ret;
169		- ret = seq_open(file, &proc_pid_maps_op);
170		- if (!ret) {
171		- struct seq_file *m = file->private_data;
172		- m->private = NULL;
	206	+ struct proc_maps_private *priv;
	207	+ int ret = -ENOMEM;
	208	+
	209	+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	210	+ if (priv) {
	211	+ priv->pid = proc_pid(inode);
	212	+ ret = seq_open(file, &proc_pid_maps_ops);
	213	+ if (!ret) {
	214	+ struct seq_file *m = file->private_data;
	215	+ m->private = priv;
	216	+ } else {
	217	+ kfree(priv);
	218	+ }
173	219	}
174	220	return ret;
175	221	}
...	...	@@ -178,6 +224,6 @@
178	224	.open = maps_open,
179	225	.read = seq_read,
180	226	.llseek = seq_lseek,
181		- .release = seq_release,
	227	+ .release = seq_release_private,
182	228	};
...	...	@@ -268,7 +268,9 @@
268	268	struct proc_maps_private {
269	269	struct pid *pid;
270	270	struct task_struct *task;
	271	+#ifdef CONFIG_MMU
271	272	struct vm_area_struct *tail_vma;
	273	+#endif
272	274	};
273	275
274	276	#endif /* _LINUX_PROC_FS_H */