uprobes/x86: Introduce uprobe_xol_ops and arch_uprobe->ops

Introduce arch_uprobe->ops pointing to the "struct uprobe_xol_ops",
move the current UPROBE_FIX_{RIP*,IP,CALL} code into the default
set of methods and change arch_uprobe_pre/post_xol() accordingly.

This way we can add the new uprobe_xol_ops's to handle the insns
which need the special processing (rip-relative jmp/call at least).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index 3087ea9..9f8210b 100644 (file)
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -33,12 +33,17 @@ typedef u8 uprobe_opcode_t;
 #define UPROBE_SWBP_INSN               0xcc
 #define UPROBE_SWBP_INSN_SIZE             1
 
+struct uprobe_xol_ops;
+
 struct arch_uprobe {
-       u16                             fixups;
        union {
                u8                      insn[MAX_UINSN_BYTES];
                u8                      ixol[MAX_UINSN_BYTES];
        };
+
+       u16                             fixups;
+       const struct uprobe_xol_ops     *ops;
+
 #ifdef CONFIG_X86_64
        unsigned long                   rip_rela_target_address;
 #endif

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 3bb4198..13ad8a3 100644 (file)
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -402,6 +402,64 @@ static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm,
 }
 #endif /* CONFIG_X86_64 */
 
+struct uprobe_xol_ops {
+       bool    (*emulate)(struct arch_uprobe *, struct pt_regs *);
+       int     (*pre_xol)(struct arch_uprobe *, struct pt_regs *);
+       int     (*post_xol)(struct arch_uprobe *, struct pt_regs *);
+};
+
+static int default_pre_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+       pre_xol_rip_insn(auprobe, regs, &current->utask->autask);
+       return 0;
+}
+
+/*
+ * Adjust the return address pushed by a call insn executed out of line.
+ */
+static int adjust_ret_addr(unsigned long sp, long correction)
+{
+       int rasize, ncopied;
+       long ra = 0;
+
+       if (is_ia32_task())
+               rasize = 4;
+       else
+               rasize = 8;
+
+       ncopied = copy_from_user(&ra, (void __user *)sp, rasize);
+       if (unlikely(ncopied))
+               return -EFAULT;
+
+       ra += correction;
+       ncopied = copy_to_user((void __user *)sp, &ra, rasize);
+       if (unlikely(ncopied))
+               return -EFAULT;
+
+       return 0;
+}
+
+static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+       struct uprobe_task *utask = current->utask;
+       long correction = (long)(utask->vaddr - utask->xol_vaddr);
+       int ret = 0;
+
+       handle_riprel_post_xol(auprobe, regs, &correction);
+       if (auprobe->fixups & UPROBE_FIX_IP)
+               regs->ip += correction;
+
+       if (auprobe->fixups & UPROBE_FIX_CALL)
+               ret = adjust_ret_addr(regs->sp, correction);
+
+       return ret;
+}
+
+static struct uprobe_xol_ops default_xol_ops = {
+       .pre_xol  = default_pre_xol_op,
+       .post_xol = default_post_xol_op,
+};
+
 /**
  * arch_uprobe_analyze_insn - instruction analysis including validity and fixups.
  * @mm: the probed address space.
@@ -464,6 +522,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
        if (fix_call)
                auprobe->fixups |= UPROBE_FIX_CALL;
 
+       auprobe->ops = &default_xol_ops;
        return 0;
 }
 
@@ -485,33 +544,8 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
        if (test_tsk_thread_flag(current, TIF_BLOCKSTEP))
                set_task_blockstep(current, false);
 
-       pre_xol_rip_insn(auprobe, regs, &utask->autask);
-       return 0;
-}
-
-/*
- * This function is called by arch_uprobe_post_xol() to adjust the return
- * address pushed by a call instruction executed out of line.
- */
-static int adjust_ret_addr(unsigned long sp, long correction)
-{
-       int rasize, ncopied;
-       long ra = 0;
-
-       if (is_ia32_task())
-               rasize = 4;
-       else
-               rasize = 8;
-
-       ncopied = copy_from_user(&ra, (void __user *)sp, rasize);
-       if (unlikely(ncopied))
-               return -EFAULT;
-
-       ra += correction;
-       ncopied = copy_to_user((void __user *)sp, &ra, rasize);
-       if (unlikely(ncopied))
-               return -EFAULT;
-
+       if (auprobe->ops->pre_xol)
+               return auprobe->ops->pre_xol(auprobe, regs);
        return 0;
 }
 
@@ -560,11 +594,8 @@ bool arch_uprobe_xol_was_trapped(struct task_struct *t)
 int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
        struct uprobe_task *utask = current->utask;
-       long correction;
-       int result = 0;
 
        WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
-
        current->thread.trap_nr = utask->autask.saved_trap_nr;
        /*
         * arch_uprobe_pre_xol() doesn't save the state of TIF_BLOCKSTEP
@@ -576,15 +607,9 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
        else if (!(auprobe->fixups & UPROBE_FIX_SETF))
                regs->flags &= ~X86_EFLAGS_TF;
 
-       correction = (long)(utask->vaddr - utask->xol_vaddr);
-       handle_riprel_post_xol(auprobe, regs, &correction);
-       if (auprobe->fixups & UPROBE_FIX_IP)
-               regs->ip += correction;
-
-       if (auprobe->fixups & UPROBE_FIX_CALL)
-               result = adjust_ret_addr(regs->sp, correction);
-
-       return result;
+       if (auprobe->ops->post_xol)
+               return auprobe->ops->post_xol(auprobe, regs);
+       return 0;
 }
 
 /* callback routine for handling exceptions. */
@@ -642,6 +667,10 @@ static bool __skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
        int i;
 
+       if (auprobe->ops->emulate)
+               return auprobe->ops->emulate(auprobe, regs);
+
+       /* TODO: move this code into ->emulate() hook */
        for (i = 0; i < MAX_UINSN_BYTES; i++) {
                if (auprobe->insn[i] == 0x66)
                        continue;