Uprobes uses notifier mechanism to get in control when an application
encounters a breakpoint or a singlestep exception.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/uprobes.h | 4 ++++
arch/x86/kernel/signal.c | 14 ++++++++++++++
arch/x86/kernel/uprobes.c | 29 +++++++++++++++++++++++++++++
3 files changed, 47 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index 35ac9d7..7d9d0a5 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -23,6 +23,8 @@
* Jim Keniston
*/
+#include <linux/notifier.h>
+
typedef u8 uprobe_opcode_t;
#define MAX_UINSN_BYTES 16
#define UPROBES_XOL_SLOT_BYTES 128 /* to keep it cache aligned */
@@ -40,4 +42,6 @@ struct uprobe_arch_info {};
struct uprobe;
extern int analyze_insn(struct task_struct *tsk, struct uprobe *uprobe);
extern void set_instruction_pointer(struct pt_regs *regs, unsigned long vaddr);
+extern int uprobe_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data);
#endif /* _ASM_UPROBES_H */
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 54ddaeb..97fac33 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -20,6 +20,7 @@
#include <linux/personality.h>
#include <linux/uaccess.h>
#include <linux/user-return-notifier.h>
+#include <linux/uprobes.h>
#include <asm/processor.h>
#include <asm/ucontext.h>
@@ -820,6 +821,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
mce_notify_process();
#endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
+ if (thread_info_flags & _TIF_UPROBE) {
+ clear_thread_flag(TIF_UPROBE);
+#ifdef CONFIG_X86_32
+ /*
+ * On x86_32, do_notify_resume() gets called with
+ * interrupts disabled. Hence enable interrupts if they
+ * are still disabled.
+ */
+ local_irq_enable();
+#endif
+ uprobe_notify_resume(regs);
+ }
+
/* deal with pending signal delivery */
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs);
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index e1c1dfe..8ec759a 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -393,3 +393,32 @@ void set_instruction_pointer(struct pt_regs *regs, unsigned long vaddr)
{
regs->ip = vaddr;
}
+
+/*
+ * Wrapper routine for handling exceptions.
+ */
+int uprobe_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ struct die_args *args = data;
+ struct pt_regs *regs = args->regs;
+ int ret = NOTIFY_DONE;
+
+ /* We are only interested in userspace traps */
+ if (regs && !user_mode_vm(regs))
+ return NOTIFY_DONE;
+
+ switch (val) {
+ case DIE_INT3:
+ /* Run your handler here */
+ if (uprobe_bkpt_notifier(regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_DEBUG:
+ if (uprobe_post_notifier(regs))
+ ret = NOTIFY_STOP;
+ default:
+ break;
+ }
+ return ret;
+}
--
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