[PATCH] kprobe handler: discard user space trap

Currently kprobe handler traps only happen in kernel space, so function
kprobe_exceptions_notify should skip traps which happen in user space.
This patch modifies this, and it is based on 2.6.16-rc4.

Signed-off-by: bibo mao <bibo.mao@intel.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>
Cc: <hiramatu@sdl.hitachi.co.jp>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index acdcc64..df1b346 100644 (file)
--- a/arch/i386/kernel/kprobes.c
+++ b/arch/i386/kernel/kprobes.c
@@ -203,13 +203,14 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
 {
        struct kprobe *p;
        int ret = 0;
-       kprobe_opcode_t *addr = NULL;
-       unsigned long *lp;
+       kprobe_opcode_t *addr;
        struct kprobe_ctlblk *kcb;
 #ifdef CONFIG_PREEMPT
        unsigned pre_preempt_count = preempt_count();
 #endif /* CONFIG_PREEMPT */
 
+       addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
+
        /*
         * We don't want to be preempted for the entire
         * duration of kprobe processing
@@ -217,17 +218,6 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
        preempt_disable();
        kcb = get_kprobe_ctlblk();
 
-       /* Check if the application is using LDT entry for its code segment and
-        * calculate the address by reading the base address from the LDT entry.
-        */
-       if ((regs->xcs & 4) && (current->mm)) {
-               lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8)
-                                       + (char *) current->mm->context.ldt);
-               addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip -
-                                               sizeof(kprobe_opcode_t));
-       } else {
-               addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
-       }
        /* Check we're not actually recursing */
        if (kprobe_running()) {
                p = get_kprobe(addr);
@@ -579,6 +569,9 @@ 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))

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 50ae8c7..45b8479 100644 (file)
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -740,6 +740,9 @@ 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_BREAK:
                /* err is break number from ia64_bad_break() */

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index cb1fe58..aea25dd 100644 (file)
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -396,6 +396,9 @@ 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_BPT:
                if (kprobe_handler(args->regs))

diff --git a/arch/sparc64/kernel/kprobes.c b/arch/sparc64/kernel/kprobes.c
index b9a9ce7..d91c318 100644 (file)
--- a/arch/sparc64/kernel/kprobes.c
+++ b/arch/sparc64/kernel/kprobes.c
@@ -324,6 +324,9 @@ 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_DEBUG:
                if (kprobe_handler(args->regs))

diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
index 14f0ced..218e015 100644 (file)
--- a/arch/x86_64/kernel/kprobes.c
+++ b/arch/x86_64/kernel/kprobes.c
@@ -601,6 +601,9 @@ 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))