linux-kernel - [PATCH 3/3] lkdtm/stackleak: Fix noinstr violation

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Date:   Wed, 12 Apr 2023 10:24:08 -0700
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>, frederic@...nel.org,
        paulmck@...nel.org, keescook@...omium.org
Subject: [PATCH 3/3] lkdtm/stackleak: Fix noinstr violation

Fixes the following warning:

  vmlinux.o: warning: objtool: check_stackleak_irqoff+0x2b6: call to _printk() leaves .noinstr.text section

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 drivers/misc/lkdtm/stackleak.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/misc/lkdtm/stackleak.c b/drivers/misc/lkdtm/stackleak.c
index 025b133297a6..f1d022160913 100644
--- a/drivers/misc/lkdtm/stackleak.c
+++ b/drivers/misc/lkdtm/stackleak.c
@@ -43,12 +43,14 @@ static void noinstr check_stackleak_irqoff(void)
 	 * STACK_END_MAGIC, and in either casee something is seriously wrong.
 	 */
 	if (current_sp < task_stack_low || current_sp >= task_stack_high) {
+		instrumentation_begin();
 		pr_err("FAIL: current_stack_pointer (0x%lx) outside of task stack bounds [0x%lx..0x%lx]\n",
 		       current_sp, task_stack_low, task_stack_high - 1);
 		test_failed = true;
 		goto out;
 	}
 	if (lowest_sp < task_stack_low || lowest_sp >= task_stack_high) {
+		instrumentation_begin();
 		pr_err("FAIL: current->lowest_stack (0x%lx) outside of task stack bounds [0x%lx..0x%lx]\n",
 		       lowest_sp, task_stack_low, task_stack_high - 1);
 		test_failed = true;
@@ -86,11 +88,14 @@ static void noinstr check_stackleak_irqoff(void)
 		if (*(unsigned long *)poison_low == STACKLEAK_POISON)
 			continue;
 
+		instrumentation_begin();
 		pr_err("FAIL: non-poison value %lu bytes below poison boundary: 0x%lx\n",
 		       poison_high - poison_low, *(unsigned long *)poison_low);
 		test_failed = true;
+		goto out;
 	}
 
+	instrumentation_begin();
 	pr_info("stackleak stack usage:\n"
 		"  high offset: %lu bytes\n"
 		"  current:     %lu bytes\n"
@@ -113,6 +118,7 @@ static void noinstr check_stackleak_irqoff(void)
 	} else {
 		pr_info("OK: the rest of the thread stack is properly erased\n");
 	}
+	instrumentation_end();
 }
 
 static void lkdtm_STACKLEAK_ERASING(void)
-- 
2.39.2