Merge branch 'uprobes/core' of...

Merge branch 'uprobes/core' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc into perf/core

Pull uprobes fixes and cleanups from Oleg Nesterov:

  "Any probed jmp/call can kill the application, see the changelog in 11/15."
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/uprobes.h

@@ -33,15 +33,27 @@ 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;
+
+	union {
 #ifdef CONFIG_X86_64
 		unsigned long			rip_rela_target_address;
 #endif
+		struct {
+			s32	offs;
+			u8	ilen;
+			u8	opc1;
+		}				branch;
+	};
 };
 
 struct arch_uprobe_task {

kernel/events/uprobes.c

@@ -60,8 +60,6 @@ static struct percpu_rw_semaphore dup_mmap_sem;
 
 /* Have a copy of original instruction */
 #define UPROBE_COPY_INSN	0
-/* Can skip singlestep */
-#define UPROBE_SKIP_SSTEP	1
 
 struct uprobe {
 	struct rb_node		rb_node;	/* node in the rb tree */
@@ -491,12 +489,9 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
 	uprobe->offset = offset;
 	init_rwsem(&uprobe->register_rwsem);
 	init_rwsem(&uprobe->consumer_rwsem);
-	/* For now assume that the instruction need not be single-stepped */
-	__set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
 
 	/* add to uprobes_tree, sorted on inode:offset */
 	cur_uprobe = insert_uprobe(uprobe);
-
 	/* a uprobe exists for this inode:offset combination */
 	if (cur_uprobe) {
 		kfree(uprobe);
@@ -1628,20 +1623,6 @@ bool uprobe_deny_signal(void)
 	return true;
 }
 
-/*
- * Avoid singlestepping the original instruction if the original instruction
- * is a NOP or can be emulated.
- */
-static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
-{
-	if (test_bit(UPROBE_SKIP_SSTEP, &uprobe->flags)) {
-		if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
-			return true;
-		clear_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
-	}
-	return false;
-}
-
 static void mmf_recalc_uprobes(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
@@ -1868,13 +1849,13 @@ static void handle_swbp(struct pt_regs *regs)
 
 	handler_chain(uprobe, regs);
 
-	if (can_skip_sstep(uprobe, regs))
+	if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
 		goto out;
 
 	if (!pre_ssout(uprobe, regs, bp_vaddr))
 		return;
 
-	/* can_skip_sstep() succeeded, or restart if can't singlestep */
+	/* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */
 out:
 	put_uprobe(uprobe);
 }
@@ -1886,10 +1867,11 @@ static void handle_swbp(struct pt_regs *regs)
 static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
 {
 	struct uprobe *uprobe;
+	int err = 0;
 
 	uprobe = utask->active_uprobe;
 	if (utask->state == UTASK_SSTEP_ACK)
-		arch_uprobe_post_xol(&uprobe->arch, regs);
+		err = arch_uprobe_post_xol(&uprobe->arch, regs);
 	else if (utask->state == UTASK_SSTEP_TRAPPED)
 		arch_uprobe_abort_xol(&uprobe->arch, regs);
 	else
@@ -1903,6 +1885,11 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
 	spin_lock_irq(&current->sighand->siglock);
 	recalc_sigpending(); /* see uprobe_deny_signal() */
 	spin_unlock_irq(&current->sighand->siglock);
+
+	if (unlikely(err)) {
+		uprobe_warn(current, "execute the probed insn, sending SIGILL.");
+		force_sig_info(SIGILL, SEND_SIG_FORCED, current);
+	}
 }
 
 /*