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SubjectRe: [PATCH] Kprobes /proc entry
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Greg KH ha scritto:
> Also, why not use the seqfile interface for this, to prevent overflowing
> the read buffer?
Great idea!

> Am I missing where you allocate the space for the data to be put into?
seq_read does the job now. It manages to allocate PAGE_SIZE bytes.
Assuming function, hook and module names occupy KSYM_NAME_LEN bytes each,
maximum length will be 424 bytes for each kprobe. I don't think it would be
useful to allocate more memory than PAGE_SIZE. Please, let me know your opinion.



- --- ./kernel/kprobes.c 2005-01-19 11:03:03.000000000 +0100
+++ ./kernel/kprobes.c 2005-01-20 15:02:47.000000000 +0100
@@ -33,6 +33,10 @@
#include <linux/hash.h>
#include <linux/init.h>
#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
+#include <linux/seq_file.h>
#include <asm/cacheflush.h>
#include <asm/errno.h>
#include <asm/kdebug.h>
@@ -45,6 +49,13 @@
unsigned int kprobe_cpu = NR_CPUS;
static DEFINE_SPINLOCK(kprobe_lock);

+static char *ktype[] = {
+ "PRE",
+ "POST",
+ "FAULT",
+ "BREAK",
+};
+
/* Locks kprobe: irqs must be disabled */
void lock_kprobes(void)
{
@@ -131,15 +142,92 @@
unregister_kprobe(&jp->kp);
}

+static void kprobes_print(struct seq_file *seq, unsigned long addr,
+ unsigned long handler, int type)
+{
+ char *module, namebuf[KSYM_NAME_LEN+1];
+ const char *hook, *func;
+ unsigned long off, size;
+
+ func = kallsyms_lookup(addr, &size, &off, &module, namebuf);
+ seq_printf(seq, "%s\t0x%lx(%s+%#lx)\t", ktype[type], addr, func, off);
+ hook = kallsyms_lookup(handler, &size, &off, &module, namebuf);
+ seq_printf(seq, "0x%lx(%s)\t%s\n", handler, hook,
+ strlen(module) ? module : "[built-in]");
+}
+
+static int kprobes_show(struct seq_file *seq, void *unused)
+{
+ int i;
+ struct kprobe *k;
+ struct hlist_node *node;
+ unsigned long addr, handler;
+
+ spin_lock(&kprobe_lock);
+ for(i = 0; i < KPROBE_TABLE_SIZE; i++) {
+ hlist_for_each_entry(k, node, &kprobe_table[i], hlist) {
+ if(!k)
+ continue;
+ addr = (unsigned long)k->addr;
+ if(k->pre_handler) {
+ handler = (unsigned long)k->pre_handler;
+ kprobes_print(seq, addr, handler, PRE);
+ }
+ if(k->post_handler) {
+ handler = (unsigned long)k->post_handler;
+ kprobes_print(seq, addr, handler, POST);
+ }
+ if(k->fault_handler) {
+ handler = (unsigned long)k->fault_handler;
+ kprobes_print(seq, addr, handler, FAULT);
+ }
+ if(k->break_handler) {
+ handler = (unsigned long)k->break_handler;
+ kprobes_print(seq, addr, handler, BREAK);
+ }
+ }
+ }
+ spin_unlock(&kprobe_lock);
+ return 0;
+}
+
+static int kprobes_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, kprobes_show, NULL);
+}
+
+static struct file_operations kprobes_fops = {
+ .open = kprobes_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+ .owner = THIS_MODULE
+};
+
static int __init init_kprobes(void)
{
int i, err = 0;
+ struct dentry *kprobes_dir, *kprobes_list;

/* FIXME allocate the probe table, currently defined statically */
/* initialize all list heads */
for (i = 0; i < KPROBE_TABLE_SIZE; i++)
INIT_HLIST_HEAD(&kprobe_table[i]);

+ kprobes_dir = debugfs_create_dir("kprobes", NULL);
+ if(!kprobes_dir) {
+ printk("kprobes: could not create debugfs entry\n");
+ goto finish;
+ }
+ kprobes_list = debugfs_create_file("list", S_IRUGO, kprobes_dir,
+ NULL, &kprobes_fops);
+ if(!kprobes_list) {
+ printk("kprobes: could not create debugfs entry\n");
+ debugfs_remove(kprobes_dir);
+ goto finish;
+ }
+
+finish:
err = register_die_notifier(&kprobe_exceptions_nb);
return err;
}
- --- ./include/linux/kprobes.h 2005-01-03 20:40:51.000000000 +0100
+++ ./include/linux/kprobes.h 2005-01-20 13:59:27.000000000 +0100
@@ -82,6 +82,13 @@
kprobe_opcode_t *entry; /* probe handling code to jump to */
};

+enum kprobe_type {
+ PRE=0,
+ POST,
+ FAULT,
+ BREAK,
+};
+
#ifdef CONFIG_KPROBES
/* Locks kprobe: irq must be disabled */
void lock_kprobes(void);
Signed-off-by: Luca Falavigna <dktrkranz@gmail.com>



Regards,

Luca
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