- 2.6.17 port work build breaks, but the patch set is relativly stable

[linux-flexiantxendom0-3.2.10.git] / arch / x86_64 / kernel / kprobes.c

diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
index 8b866a8..fa1d19c 100644 (file)
--- a/arch/x86_64/kernel/kprobes.c
+++ b/arch/x86_64/kernel/kprobes.c
@@ -37,10 +37,12 @@
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/preempt.h>
+#include <linux/module.h>
 
 #include <asm/cacheflush.h>
 #include <asm/pgtable.h>
 #include <asm/kdebug.h>
+#include <asm/uaccess.h>
 
 void jprobe_return_end(void);
 static void __kprobes arch_copy_kprobe(struct kprobe *p);
@@ -51,7 +53,7 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 /*
  * returns non-zero if opcode modifies the interrupt flag.
  */
-static inline int is_IF_modifier(kprobe_opcode_t *insn)
+static __always_inline int is_IF_modifier(kprobe_opcode_t *insn)
 {
        switch (*insn) {
        case 0xfa:              /* cli */
@@ -82,7 +84,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
  * If it does, return the address of the 32-bit displacement word.
  * If not, return null.
  */
-static inline s32 *is_riprel(u8 *insn)
+static s32 __kprobes *is_riprel(u8 *insn)
 {
 #define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf)               \
        (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) |   \
@@ -222,12 +224,12 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p)
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-       down(&kprobe_mutex);
+       mutex_lock(&kprobe_mutex);
        free_insn_slot(p->ainsn.insn);
-       up(&kprobe_mutex);
+       mutex_unlock(&kprobe_mutex);
 }
 
-static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
        kcb->prev_kprobe.kp = kprobe_running();
        kcb->prev_kprobe.status = kcb->kprobe_status;
@@ -235,7 +237,7 @@ static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
        kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags;
 }
 
-static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
        __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
        kcb->kprobe_status = kcb->prev_kprobe.status;
@@ -243,7 +245,7 @@ static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
        kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags;
 }
 
-static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
                                struct kprobe_ctlblk *kcb)
 {
        __get_cpu_var(current_kprobe) = p;
@@ -512,13 +514,13 @@ static void __kprobes resume_execution(struct kprobe *p,
                *tos = orig_rip + (*tos - copy_rip);
                break;
        case 0xff:
-               if ((*insn & 0x30) == 0x10) {
+               if ((insn[1] & 0x30) == 0x10) {
                        /* call absolute, indirect */
                        /* Fix return addr; rip is correct. */
                        next_rip = regs->rip;
                        *tos = orig_rip + (*tos - copy_rip);
-               } else if (((*insn & 0x31) == 0x20) ||  /* jmp near, absolute indirect */
-                          ((*insn & 0x31) == 0x21)) {  /* jmp far, absolute indirect */
+               } else if (((insn[1] & 0x31) == 0x20) ||        /* jmp near, absolute indirect */
+                          ((insn[1] & 0x31) == 0x21)) {        /* jmp far, absolute indirect */
                        /* rip is correct. */
                        next_rip = regs->rip;
                }
@@ -578,16 +580,62 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
        struct kprobe *cur = kprobe_running();
        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+       const struct exception_table_entry *fixup;
 
-       if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
-               return 1;
-
-       if (kcb->kprobe_status & KPROBE_HIT_SS) {
-               resume_execution(cur, regs, kcb);
+       switch(kcb->kprobe_status) {
+       case KPROBE_HIT_SS:
+       case KPROBE_REENTER:
+               /*
+                * We are here because the instruction being single
+                * stepped caused a page fault. We reset the current
+                * kprobe and the rip points back to the probe address
+                * and allow the page fault handler to continue as a
+                * normal page fault.
+                */
+               regs->rip = (unsigned long)cur->addr;
                regs->eflags |= kcb->kprobe_old_rflags;
-
-               reset_current_kprobe();
+               if (kcb->kprobe_status == KPROBE_REENTER)
+                       restore_previous_kprobe(kcb);
+               else
+                       reset_current_kprobe();
                preempt_enable_no_resched();
+               break;
+       case KPROBE_HIT_ACTIVE:
+       case KPROBE_HIT_SSDONE:
+               /*
+                * We increment the nmissed count for accounting,
+                * we can also use npre/npostfault count for accouting
+                * these specific fault cases.
+                */
+               kprobes_inc_nmissed_count(cur);
+
+               /*
+                * We come here because instructions in the pre/post
+                * handler caused the page_fault, this could happen
+                * if handler tries to access user space by
+                * copy_from_user(), get_user() etc. Let the
+                * user-specified handler try to fix it first.
+                */
+               if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
+                       return 1;
+
+               /*
+                * In case the user-specified fault handler returned
+                * zero, try to fix up.
+                */
+               fixup = search_exception_tables(regs->rip);
+               if (fixup) {
+                       regs->rip = fixup->fixup;
+                       return 1;
+               }
+
+               /*
+                * fixup() could not handle it,
+                * Let do_page_fault() fix it.
+                */
+               break;
+       default:
+               break;
        }
        return 0;
 }
@@ -601,6 +649,9 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
        struct die_args *args = (struct die_args *)data;
        int ret = NOTIFY_DONE;
 
+       if (args->regs && user_mode(args->regs))
+               return ret;
+
        switch (val) {
        case DIE_INT3:
                if (kprobe_handler(args->regs))