1 files changed, 120 insertions, 50 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 334f37472c56..90c0e82b650c 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -36,6 +36,7 @@
 #include <linux/hash.h>
 #include <linux/init.h>
 #include <linux/module.h>
+#include <linux/moduleloader.h>
 #include <asm/cacheflush.h>
 #include <asm/errno.h>
 #include <asm/kdebug.h>
@@ -50,6 +51,106 @@ unsigned int kprobe_cpu = NR_CPUS;
 static DEFINE_SPINLOCK(kprobe_lock);
 static struct kprobe *curr_kprobe;
 
+/*
+ * kprobe->ainsn.insn points to the copy of the instruction to be
+ * single-stepped. x86_64, POWER4 and above have no-exec support and
+ * stepping on the instruction on a vmalloced/kmalloced/data page
+ * is a recipe for disaster
+ */
+#define INSNS_PER_PAGE  (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
+
+struct kprobe_insn_page {
+        struct hlist_node hlist;
+        kprobe_opcode_t *insns;         /* Page of instruction slots */
+        char slot_used[INSNS_PER_PAGE];
+        int nused;
+};
+
+static struct hlist_head kprobe_insn_pages;
+
+/**
+ * get_insn_slot() - Find a slot on an executable page for an instruction.
+ * We allocate an executable page if there's no room on existing ones.
+ */
+kprobe_opcode_t *get_insn_slot(void)
+{
+        struct kprobe_insn_page *kip;
+        struct hlist_node *pos;
+
+        hlist_for_each(pos, &kprobe_insn_pages) {
+                kip = hlist_entry(pos, struct kprobe_insn_page, hlist);
+                if (kip->nused < INSNS_PER_PAGE) {
+                        int i;
+                        for (i = 0; i < INSNS_PER_PAGE; i++) {
+                                if (!kip->slot_used[i]) {
+                                        kip->slot_used[i] = 1;
+                                        kip->nused++;
+                                        return kip->insns + (i * MAX_INSN_SIZE);
+                                }
+                        }
+                        /* Surprise!  No unused slots.  Fix kip->nused. */
+                        kip->nused = INSNS_PER_PAGE;
+                }
+        }
+
+        /* All out of space.  Need to allocate a new page. Use slot 0.*/
+        kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
+        if (!kip) {
+                return NULL;
+        }
+
+        /*
+         * Use module_alloc so this page is within +/- 2GB of where the
+         * kernel image and loaded module images reside. This is required
+         * so x86_64 can correctly handle the %rip-relative fixups.
+         */
+        kip->insns = module_alloc(PAGE_SIZE);
+        if (!kip->insns) {
+                kfree(kip);
+                return NULL;
+        }
+        INIT_HLIST_NODE(&kip->hlist);
+        hlist_add_head(&kip->hlist, &kprobe_insn_pages);
+        memset(kip->slot_used, 0, INSNS_PER_PAGE);
+        kip->slot_used[0] = 1;
+        kip->nused = 1;
+        return kip->insns;
+}
+
+void free_insn_slot(kprobe_opcode_t *slot)
+{
+        struct kprobe_insn_page *kip;
+        struct hlist_node *pos;
+
+        hlist_for_each(pos, &kprobe_insn_pages) {
+                kip = hlist_entry(pos, struct kprobe_insn_page, hlist);
+                if (kip->insns <= slot &&
+                    slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
+                        int i = (slot - kip->insns) / MAX_INSN_SIZE;
+                        kip->slot_used[i] = 0;
+                        kip->nused--;
+                        if (kip->nused == 0) {
+                                /*
+                                 * Page is no longer in use.  Free it unless
+                                 * it's the last one.  We keep the last one
+                                 * so as not to have to set it up again the
+                                 * next time somebody inserts a probe.
+                                 */
+                                hlist_del(&kip->hlist);
+                                if (hlist_empty(&kprobe_insn_pages)) {
+                                        INIT_HLIST_NODE(&kip->hlist);
+                                        hlist_add_head(&kip->hlist,
+                                                &kprobe_insn_pages);
+                                } else {
+                                        module_free(NULL, kip->insns);
+                                        kfree(kip);
+                                }
+                        }
+                        return;
+                }
+        }
+}
+
 /* Locks kprobe: irqs must be disabled */
 void lock_kprobes(void)
 {
@@ -139,12 +240,6 @@ static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
         return 0;
 }
 
-struct kprobe trampoline_p = {
-                .addr = (kprobe_opcode_t *) &kretprobe_trampoline,
-                .pre_handler = trampoline_probe_handler,
-                .post_handler = trampoline_post_handler
-};
-
 struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp)
 {
         struct hlist_node *node;
@@ -163,35 +258,18 @@ static struct kretprobe_instance *get_used_rp_inst(struct kretprobe *rp)
         return NULL;
 }
 
-struct kretprobe_instance *get_rp_inst(void *sara)
-{
-        struct hlist_head *head;
-        struct hlist_node *node;
-        struct task_struct *tsk;
-        struct kretprobe_instance *ri;
-
-        tsk = arch_get_kprobe_task(sara);
-        head = &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
-        hlist_for_each_entry(ri, node, head, hlist) {
-                if (ri->stack_addr == sara)
-                        return ri;
-        }
-        return NULL;
-}
-
 void add_rp_inst(struct kretprobe_instance *ri)
 {
-        struct task_struct *tsk;
         /*
          * Remove rp inst off the free list -
          * Add it back when probed function returns
          */
         hlist_del(&ri->uflist);
-        tsk = arch_get_kprobe_task(ri->stack_addr);
+
         /* Add rp inst onto table */
         INIT_HLIST_NODE(&ri->hlist);
         hlist_add_head(&ri->hlist,
-                        &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)]);
+                        &kretprobe_inst_table[hash_ptr(ri->task, KPROBE_HASH_BITS)]);
 
         /* Also add this rp inst to the used list. */
         INIT_HLIST_NODE(&ri->uflist);
@@ -218,34 +296,25 @@ struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk)
         return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
 }
 
-struct kretprobe_instance *get_rp_inst_tsk(struct task_struct *tk)
-{
-        struct task_struct *tsk;
-        struct hlist_head *head;
-        struct hlist_node *node;
-        struct kretprobe_instance *ri;
-
-        head = &kretprobe_inst_table[hash_ptr(tk, KPROBE_HASH_BITS)];
-
-        hlist_for_each_entry(ri, node, head, hlist) {
-                tsk = arch_get_kprobe_task(ri->stack_addr);
-                if (tsk == tk)
-                        return ri;
-        }
-        return NULL;
-}
-
 /*
- * This function is called from do_exit or do_execv when task tk's stack is
- * about to be recycled. Recycle any function-return probe instances
- * associated with this task. These represent probed functions that have
- * been called but may never return.
+ * This function is called from exit_thread or flush_thread when task tk's
+ * stack is being recycled so that we can recycle any function-return probe
+ * instances associated with this task. These left over instances represent
+ * probed functions that have been called but will never return.
  */
 void kprobe_flush_task(struct task_struct *tk)
 {
+        struct kretprobe_instance *ri;
+        struct hlist_head *head;
+        struct hlist_node *node, *tmp;
         unsigned long flags = 0;
+
         spin_lock_irqsave(&kprobe_lock, flags);
-        arch_kprobe_flush_task(tk);
+        head = kretprobe_inst_table_head(current);
+        hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+                if (ri->task == tk)
+                        recycle_rp_inst(ri);
+        }
         spin_unlock_irqrestore(&kprobe_lock, flags);
 }
 
@@ -505,9 +574,10 @@ static int __init init_kprobes(void)
                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
         }
 
-        err = register_die_notifier(&kprobe_exceptions_nb);
-        /* Register the trampoline probe for return probe */
-        register_kprobe(&trampoline_p);
+        err = arch_init();
+        if (!err)
+                err = register_die_notifier(&kprobe_exceptions_nb);
+
         return err;
 }