1 files changed, 157 insertions, 0 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
new file mode 100644
index 000000000000..1d5dd1337bd1
--- /dev/null
+++ b/kernel/kprobes.c
@@ -0,0 +1,157 @@
+/*
+ *  Kernel Probes (KProbes)
+ *  kernel/kprobes.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2004
+ *
+ * 2002-Oct     Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
+ *              Probes initial implementation (includes suggestions from
+ *              Rusty Russell).
+ * 2004-Aug     Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
+ *              hlists and exceptions notifier as suggested by Andi Kleen.
+ * 2004-July    Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
+ *              interface to access function arguments.
+ * 2004-Sep     Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
+ *              exceptions notifier to be first on the priority list.
+ */
+#include <linux/kprobes.h>
+#include <linux/spinlock.h>
+#include <linux/hash.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <asm/cacheflush.h>
+#include <asm/errno.h>
+#include <asm/kdebug.h>
+
+#define KPROBE_HASH_BITS 6
+#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
+
+static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
+
+unsigned int kprobe_cpu = NR_CPUS;
+static DEFINE_SPINLOCK(kprobe_lock);
+
+/* Locks kprobe: irqs must be disabled */
+void lock_kprobes(void)
+{
+        spin_lock(&kprobe_lock);
+        kprobe_cpu = smp_processor_id();
+}
+
+void unlock_kprobes(void)
+{
+        kprobe_cpu = NR_CPUS;
+        spin_unlock(&kprobe_lock);
+}
+
+/* You have to be holding the kprobe_lock */
+struct kprobe *get_kprobe(void *addr)
+{
+        struct hlist_head *head;
+        struct hlist_node *node;
+
+        head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
+        hlist_for_each(node, head) {
+                struct kprobe *p = hlist_entry(node, struct kprobe, hlist);
+                if (p->addr == addr)
+                        return p;
+        }
+        return NULL;
+}
+
+int register_kprobe(struct kprobe *p)
+{
+        int ret = 0;
+        unsigned long flags = 0;
+
+        if ((ret = arch_prepare_kprobe(p)) != 0) {
+                goto rm_kprobe;
+        }
+        spin_lock_irqsave(&kprobe_lock, flags);
+        INIT_HLIST_NODE(&p->hlist);
+        if (get_kprobe(p->addr)) {
+                ret = -EEXIST;
+                goto out;
+        }
+        arch_copy_kprobe(p);
+
+        hlist_add_head(&p->hlist,
+                       &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
+
+        p->opcode = *p->addr;
+        *p->addr = BREAKPOINT_INSTRUCTION;
+        flush_icache_range((unsigned long) p->addr,
+                           (unsigned long) p->addr + sizeof(kprobe_opcode_t));
+out:
+        spin_unlock_irqrestore(&kprobe_lock, flags);
+rm_kprobe:
+        if (ret == -EEXIST)
+                arch_remove_kprobe(p);
+        return ret;
+}
+
+void unregister_kprobe(struct kprobe *p)
+{
+        unsigned long flags;
+        arch_remove_kprobe(p);
+        spin_lock_irqsave(&kprobe_lock, flags);
+        *p->addr = p->opcode;
+        hlist_del(&p->hlist);
+        flush_icache_range((unsigned long) p->addr,
+                           (unsigned long) p->addr + sizeof(kprobe_opcode_t));
+        spin_unlock_irqrestore(&kprobe_lock, flags);
+}
+
+static struct notifier_block kprobe_exceptions_nb = {
+        .notifier_call = kprobe_exceptions_notify,
+        .priority = 0x7fffffff /* we need to notified first */
+};
+
+int register_jprobe(struct jprobe *jp)
+{
+        /* Todo: Verify probepoint is a function entry point */
+        jp->kp.pre_handler = setjmp_pre_handler;
+        jp->kp.break_handler = longjmp_break_handler;
+
+        return register_kprobe(&jp->kp);
+}
+
+void unregister_jprobe(struct jprobe *jp)
+{
+        unregister_kprobe(&jp->kp);
+}
+
+static int __init init_kprobes(void)
+{
+        int i, err = 0;
+
+        /* 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]);
+
+        err = register_die_notifier(&kprobe_exceptions_nb);
+        return err;
+}
+
+__initcall(init_kprobes);
+
+EXPORT_SYMBOL_GPL(register_kprobe);
+EXPORT_SYMBOL_GPL(unregister_kprobe);
+EXPORT_SYMBOL_GPL(register_jprobe);
+EXPORT_SYMBOL_GPL(unregister_jprobe);
+EXPORT_SYMBOL_GPL(jprobe_return);