From a21d81ec8b00571cb5987fe04ce74a3fe873351c Mon Sep 17 00:00:00 2001
From: David Smith <dsmith@redhat.com>
Date: Mon, 23 Jun 2008 12:41:45 -0500
Subject: Major update to memory map change notification code. 2008-06-23 
 David Smith  <dsmith@redhat.com>

	* tapsets.cxx (utrace_derived_probe_group::emit_probe_decl):
	Handles UDPF_NONE value.
	(utrace_derived_probe_group::emit_vm_callback_probe_decl): New
	function.
	(utrace_derived_probe_group::emit_module_decls): Calls
	emit_vm_callback_probe_decl() to set up vm_callbacks.

2008-06-23  David Smith  <dsmith@redhat.com>

	* task_finder.c (__stp_tf_vm_cb): New function.
	(stap_register_task_finder_target): Sets up syscall entry and
	syscall exit handlers.
	(__stp_find_file_based_vma): New function.
	(__stp_utrace_task_finder_target_syscall_entry): New function.
	Saves vma information off at syscall entry.
	(__stp_target_call_vm_callback): New function.
	(__stp_utrace_task_finder_target_syscall_exit): New function.
	Handles changes to memory maps based on information saved at
	syscall entry.
	* syscall.h: New file containing syscall function.
	* task_finder_vma.c: New file containing saved vma information
	handling functions.
---
 runtime/task_finder_vma.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 runtime/task_finder_vma.c

(limited to 'runtime/task_finder_vma.c')

diff --git a/runtime/task_finder_vma.c b/runtime/task_finder_vma.c
new file mode 100644
index 00000000..c849f187
--- /dev/null
+++ b/runtime/task_finder_vma.c
@@ -0,0 +1,112 @@
+#include <linux/list.h>
+#include <linux/jhash.h>
+#include <linux/mutex.h>
+
+// __stp_tf_vma_mutex protects the hash table.
+static DEFINE_MUTEX(__stp_tf_vma_mutex);
+
+#define __STP_TF_HASH_BITS 4
+#define __STP_TF_TABLE_SIZE (1 << __STP_TF_HASH_BITS)
+
+struct __stp_tf_vma_entry {
+	struct hlist_node hlist;
+
+	pid_t pid;
+	unsigned long addr;
+	unsigned long vm_start;
+	unsigned long vm_end;
+	unsigned long vm_pgoff;
+	// Is that enough?  Should we store a dcookie for vm_file?
+};
+
+static struct hlist_head __stp_tf_vma_table[__STP_TF_TABLE_SIZE];
+
+static inline u32
+__stp_tf_vma_hash(struct task_struct *tsk, unsigned long addr)
+{
+#if (__SIZEOF_LONG__ == 8)
+    return (jhash_3words(tsk->pid, (u32)addr, (u32)(addr >> 32), 0)
+	    & (__STP_TF_TABLE_SIZE - 1));
+#else
+    return (jhash_2words(tsk->pid, addr, 0) & (__STP_TF_TABLE_SIZE - 1));
+#endif
+}
+
+
+// Get vma_entry if the vma is present in the vma hash table.
+// Returns NULL if not present.
+static struct __stp_tf_vma_entry *
+__stp_tf_get_vma_entry(struct task_struct *tsk, unsigned long addr)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct __stp_tf_vma_entry *entry;
+
+	mutex_lock(&__stp_tf_vma_mutex);
+	head = &__stp_tf_vma_table[__stp_tf_vma_hash(tsk, addr)];
+	hlist_for_each_entry(entry, node, head, hlist) {
+		if (tsk->pid == entry->pid
+		    && addr == entry->addr) {
+			mutex_unlock(&__stp_tf_vma_mutex);
+			return entry;
+		}
+	}
+	mutex_unlock(&__stp_tf_vma_mutex);
+	return NULL;
+}
+
+// Add the vma info to the vma hash table.
+static int
+__stp_tf_add_vma(struct task_struct *tsk, unsigned long addr,
+		 struct vm_area_struct *vma)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct __stp_tf_vma_entry *entry;
+
+	mutex_lock(&__stp_tf_vma_mutex);
+	head = &__stp_tf_vma_table[__stp_tf_vma_hash(tsk, addr)];
+	hlist_for_each_entry(entry, node, head, hlist) {
+		if (tsk->pid == entry->pid
+		    && addr == entry->addr) {
+			printk(KERN_NOTICE
+			       "vma (pid: %d, vm_start: 0x%lx) present?\n",
+			       tsk->pid, vma->vm_start);
+			mutex_unlock(&__stp_tf_vma_mutex);
+			return -EBUSY;	/* Already there */
+		}
+	}
+
+	// Using kmalloc here to allocate an element. Could cause some
+	// memory fragmentation if overused.
+	entry = kmalloc(sizeof(struct __stp_tf_vma_entry), GFP_KERNEL);
+	if (!entry) {
+		mutex_unlock(&__stp_tf_vma_mutex);
+		return -ENOMEM;
+	}
+	entry->pid = tsk->pid;
+	entry->addr = addr;
+	entry->vm_start = vma->vm_start;
+	entry->vm_end = vma->vm_end;
+	entry->vm_pgoff = vma->vm_pgoff;
+	hlist_add_head(&entry->hlist, head);
+	mutex_unlock(&__stp_tf_vma_mutex);
+	return 0;
+}
+
+// Remove the vma entry from the vma hash table.
+static int
+__stp_tf_remove_vma_entry(struct __stp_tf_vma_entry *entry)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	int found = 0;
+
+	if (entry != NULL) {
+		mutex_lock(&__stp_tf_vma_mutex);
+		hlist_del(&entry->hlist);
+		kfree(entry);
+		mutex_unlock(&__stp_tf_vma_mutex);
+	}
+	return 0;
+}
-- 
cgit