ptrace/x86: introduce ptrace_register_breakpoint()

No functional changes, preparation. Extract the "register breakpoint" code from ptrace_get_debugreg() into the new/generic helper, ptrace_register_breakpoint(). It will have more users. The patch also adds another simple helper, ptrace_fill_bp_fields(), to factor out the arch_bp_generic_fields() logic in register/modify. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jan Kratochvil <jan.kratochvil@redhat.com> Cc: Michael Neuling <mikey@neuling.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Russell King <linux@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ptrace/x86: introduce ptrace_register_breakpoint()
No functional changes, preparation. Extract the "register breakpoint" code from ptrace_get_debugreg() into the new/generic helper, ptrace_register_breakpoint(). It will have more users. The patch also adds another simple helper, ptrace_fill_bp_fields(), to factor out the arch_bp_generic_fields() logic in register/modify. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jan Kratochvil <jan.kratochvil@redhat.com> Cc: Michael Neuling <mikey@neuling.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Russell King <linux@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Oleg Nesterov · Linus Torvalds
1 parent 29a5551341
Showing 1 changed file with 50 additions and 36 deletions Side-by-side Diff
arch/x86/kernel/ptrace.c
@@ -601,23 +601,49 @@
 	return dr7;
 }
  
-static int
-ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
-			 struct task_struct *tsk, int disabled)
+static int ptrace_fill_bp_fields(struct perf_event_attr *attr,
+					int len, int type, bool disabled)
 {
-	int err;
-	int gen_len, gen_type;
+	int err, bp_len, bp_type;
+
+	err = arch_bp_generic_fields(len, type, &bp_len, &bp_type);
+	if (!err) {
+		attr->bp_len = bp_len;
+		attr->bp_type = bp_type;
+		attr->disabled = disabled;
+	}
+
+	return err;
+}
+
+static struct perf_event *
+ptrace_register_breakpoint(struct task_struct *tsk, int len, int type,
+				unsigned long addr, bool disabled)
+{
 	struct perf_event_attr attr;
+	int err;
  
-	err = arch_bp_generic_fields(len, type, &gen_len, &gen_type);
+	ptrace_breakpoint_init(&attr);
+	attr.bp_addr = addr;
+
+	err = ptrace_fill_bp_fields(&attr, len, type, disabled);
 	if (err)
-		return err;
+		return ERR_PTR(err);
  
-	attr = bp->attr;
-	attr.bp_len = gen_len;
-	attr.bp_type = gen_type;
-	attr.disabled = disabled;
+	return register_user_hw_breakpoint(&attr, ptrace_triggered,
+						 NULL, tsk);
+}
  
+static int ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
+					int disabled)
+{
+	struct perf_event_attr attr = bp->attr;
+	int err;
+
+	err = ptrace_fill_bp_fields(&attr, len, type, disabled);
+	if (err)
+		return err;
+
 	return modify_user_hw_breakpoint(bp, &attr);
 }
  
@@ -653,7 +679,7 @@
 			break;
 		}
  
-		rc = ptrace_modify_breakpoint(bp, len, type, tsk, disabled);
+		rc = ptrace_modify_breakpoint(bp, len, type, disabled);
 		if (rc)
 			break;
 	}
  
  
  
@@ -693,26 +719,14 @@
 static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
 				      unsigned long addr)
 {
-	struct perf_event *bp;
 	struct thread_struct *t = &tsk->thread;
-	struct perf_event_attr attr;
+	struct perf_event *bp = t->ptrace_bps[nr];
 	int err = 0;
  
-	if (!t->ptrace_bps[nr]) {
-		ptrace_breakpoint_init(&attr);
+	if (!bp) {
 		/*
-		 * Put stub len and type to register (reserve) an inactive but
-		 * correct bp
-		 */
-		attr.bp_addr = addr;
-		attr.bp_len = HW_BREAKPOINT_LEN_1;
-		attr.bp_type = HW_BREAKPOINT_W;
-		attr.disabled = 1;
-
-		bp = register_user_hw_breakpoint(&attr, ptrace_triggered,
-						 NULL, tsk);
-
-		/*
+		 * Put stub len and type to create an inactive but correct bp.
+		 *
 		 * CHECKME: the previous code returned -EIO if the addr wasn't
 		 * a valid task virtual addr. The new one will return -EINVAL in
 		 *  this case.
  
  
  
  
@@ -721,20 +735,20 @@
 		 * writing for the user. And anyway this is the previous
 		 * behaviour.
 		 */
-		if (IS_ERR(bp)) {
+		bp = ptrace_register_breakpoint(tsk,
+				X86_BREAKPOINT_LEN_1, X86_BREAKPOINT_WRITE,
+				addr, true);
+		if (IS_ERR(bp))
 			err = PTR_ERR(bp);
-			goto out;
-		}
-
-		t->ptrace_bps[nr] = bp;
+		else
+			t->ptrace_bps[nr] = bp;
 	} else {
-		bp = t->ptrace_bps[nr];
+		struct perf_event_attr attr = bp->attr;
  
-		attr = bp->attr;
 		attr.bp_addr = addr;
 		err = modify_user_hw_breakpoint(bp, &attr);
 	}
-out:
+
 	return err;
 }
...	...	@@ -601,23 +601,49 @@
601	601	return dr7;
602	602	}
603	603
604		-static int
605		-ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
606		- struct task_struct *tsk, int disabled)
	604	+static int ptrace_fill_bp_fields(struct perf_event_attr *attr,
	605	+ int len, int type, bool disabled)
607	606	{
608		- int err;
609		- int gen_len, gen_type;
	607	+ int err, bp_len, bp_type;
	608	+
	609	+ err = arch_bp_generic_fields(len, type, &bp_len, &bp_type);
	610	+ if (!err) {
	611	+ attr->bp_len = bp_len;
	612	+ attr->bp_type = bp_type;
	613	+ attr->disabled = disabled;
	614	+ }
	615	+
	616	+ return err;
	617	+}
	618	+
	619	+static struct perf_event *
	620	+ptrace_register_breakpoint(struct task_struct *tsk, int len, int type,
	621	+ unsigned long addr, bool disabled)
	622	+{
610	623	struct perf_event_attr attr;
	624	+ int err;
611	625
612		- err = arch_bp_generic_fields(len, type, &gen_len, &gen_type);
	626	+ ptrace_breakpoint_init(&attr);
	627	+ attr.bp_addr = addr;
	628	+
	629	+ err = ptrace_fill_bp_fields(&attr, len, type, disabled);
613	630	if (err)
614		- return err;
	631	+ return ERR_PTR(err);
615	632
616		- attr = bp->attr;
617		- attr.bp_len = gen_len;
618		- attr.bp_type = gen_type;
619		- attr.disabled = disabled;
	633	+ return register_user_hw_breakpoint(&attr, ptrace_triggered,
	634	+ NULL, tsk);
	635	+}
620	636
	637	+static int ptrace_modify_breakpoint(struct perf_event *bp, int len, int type,
	638	+ int disabled)
	639	+{
	640	+ struct perf_event_attr attr = bp->attr;
	641	+ int err;
	642	+
	643	+ err = ptrace_fill_bp_fields(&attr, len, type, disabled);
	644	+ if (err)
	645	+ return err;
	646	+
621	647	return modify_user_hw_breakpoint(bp, &attr);
622	648	}
623	649
...	...	@@ -653,7 +679,7 @@
653	679	break;
654	680	}
655	681
656		- rc = ptrace_modify_breakpoint(bp, len, type, tsk, disabled);
	682	+ rc = ptrace_modify_breakpoint(bp, len, type, disabled);
657	683	if (rc)
658	684	break;
659	685	}
660	686
661	687
662	688
...	...	@@ -693,26 +719,14 @@
693	719	static int ptrace_set_breakpoint_addr(struct task_struct *tsk, int nr,
694	720	unsigned long addr)
695	721	{
696		- struct perf_event *bp;
697	722	struct thread_struct *t = &tsk->thread;
698		- struct perf_event_attr attr;
	723	+ struct perf_event *bp = t->ptrace_bps[nr];
699	724	int err = 0;
700	725
701		- if (!t->ptrace_bps[nr]) {
702		- ptrace_breakpoint_init(&attr);
	726	+ if (!bp) {
703	727	/*
704		- * Put stub len and type to register (reserve) an inactive but
705		- * correct bp
706		- */
707		- attr.bp_addr = addr;
708		- attr.bp_len = HW_BREAKPOINT_LEN_1;
709		- attr.bp_type = HW_BREAKPOINT_W;
710		- attr.disabled = 1;
711		-
712		- bp = register_user_hw_breakpoint(&attr, ptrace_triggered,
713		- NULL, tsk);
714		-
715		- /*
	728	+ * Put stub len and type to create an inactive but correct bp.
	729	+ *
716	730	* CHECKME: the previous code returned -EIO if the addr wasn't
717	731	* a valid task virtual addr. The new one will return -EINVAL in
718	732	* this case.
719	733
720	734
721	735
722	736
...	...	@@ -721,20 +735,20 @@
721	735	* writing for the user. And anyway this is the previous
722	736	* behaviour.
723	737	*/
724		- if (IS_ERR(bp)) {
	738	+ bp = ptrace_register_breakpoint(tsk,
	739	+ X86_BREAKPOINT_LEN_1, X86_BREAKPOINT_WRITE,
	740	+ addr, true);
	741	+ if (IS_ERR(bp))
725	742	err = PTR_ERR(bp);
726		- goto out;
727		- }
728		-
729		- t->ptrace_bps[nr] = bp;
	743	+ else
	744	+ t->ptrace_bps[nr] = bp;
730	745	} else {
731		- bp = t->ptrace_bps[nr];
	746	+ struct perf_event_attr attr = bp->attr;
732	747
733		- attr = bp->attr;
734	748	attr.bp_addr = addr;
735	749	err = modify_user_hw_breakpoint(bp, &attr);
736	750	}
737		-out:
	751	+
738	752	return err;
739	753	}
740	754