[PATCH 0/3] noinstr fixes

[PATCH 0/3] noinstr fixes

[Josh Poimboeuf]

Fix a few noinstr violations reported by objtool.

Josh Poimboeuf (3):
  context_tracking: Fix KCSAN noinstr violation
  sched: Fix KCSAN noinstr violation
  lkdtm/stackleak: Fix noinstr violation

 drivers/misc/lkdtm/stackleak.c   | 6 ++++++
 include/linux/context_tracking.h | 2 +-
 include/linux/sched/task_stack.h | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)

-- 
2.39.2

[PATCH 1/3] context_tracking: Fix KCSAN noinstr violation

[Josh Poimboeuf]

With KCSAN enabled, even empty inline stubs can be out-of-lined.

Force the context_tracking_guest_exit() stub inline.

Fixes the following warnings:

  vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x1be: call to context_tracking_guest_exit() leaves .noinstr.text section
  vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0x85: call to context_tracking_guest_exit() leaves .noinstr.text section

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 include/linux/context_tracking.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index d4afa8508a80..5ae3abd767b4 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -97,7 +97,7 @@ static inline int exception_enter(void) { return 0; }
 static inline void exception_exit(enum ctx_state prev_ctx) { }
 static inline int ct_state(void) { return -1; }
 static __always_inline bool context_tracking_guest_enter(void) { return false; }
-static inline void context_tracking_guest_exit(void) { }
+static __always_inline void context_tracking_guest_exit(void) { }
 #define CT_WARN_ON(cond) do { } while (0)
 #endif /* !CONFIG_CONTEXT_TRACKING_USER */
 
-- 
2.39.2

[PATCH 2/3] sched: Fix KCSAN noinstr violation

[Josh Poimboeuf]

With KCSAN enabled, end_of_stack() can get out-of-lined.  Force it
inline.

Fixes the following warnings:

  vmlinux.o: warning: objtool: check_stackleak_irqoff+0x2b: call to end_of_stack() leaves .noinstr.text section

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 include/linux/sched/task_stack.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h
index 5e799a47431e..f158b025c175 100644
--- a/include/linux/sched/task_stack.h
+++ b/include/linux/sched/task_stack.h
@@ -23,7 +23,7 @@ static __always_inline void *task_stack_page(const struct task_struct *task)
 
 #define setup_thread_stack(new,old)	do { } while(0)
 
-static inline unsigned long *end_of_stack(const struct task_struct *task)
+static __always_inline unsigned long *end_of_stack(const struct task_struct *task)
 {
 #ifdef CONFIG_STACK_GROWSUP
 	return (unsigned long *)((unsigned long)task->stack + THREAD_SIZE) - 1;
-- 
2.39.2

[PATCH 3/3] lkdtm/stackleak: Fix noinstr violation

[Josh Poimboeuf]

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@kernel.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

Re: [PATCH 1/3] context_tracking: Fix KCSAN noinstr violation

[Frederic Weisbecker]

Le Wed, Apr 12, 2023 at 10:24:06AM -0700, Josh Poimboeuf a écrit :
> With KCSAN enabled, even empty inline stubs can be out-of-lined.
> 
> Force the context_tracking_guest_exit() stub inline.
> 
> Fixes the following warnings:
> 
>   vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x1be: call to context_tracking_guest_exit() leaves .noinstr.text section
>   vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0x85: call to context_tracking_guest_exit() leaves .noinstr.text section
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

Acked-by: Frederic Weisbecker <frederic@kernel.org>

Thanks!

[tip: objtool/core] context_tracking: Fix KCSAN noinstr violation

[tip-bot2 for Josh Poimboeuf]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     e8deb00c0c4808654d1bf96a8f79cf1deb59b631
Gitweb:        https://git.kernel.org/tip/e8deb00c0c4808654d1bf96a8f79cf1deb59b631
Author:        Josh Poimboeuf <jpoimboe@kernel.org>
AuthorDate:    Wed, 12 Apr 2023 10:24:06 -07:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 14 Apr 2023 16:08:27 +02:00

context_tracking: Fix KCSAN noinstr violation

With KCSAN enabled, even empty inline stubs can be out-of-lined.

Force the context_tracking_guest_exit() stub inline.

Fixes the following warnings:

  vmlinux.o: warning: objtool: vmx_vcpu_enter_exit+0x1be: call to context_tracking_guest_exit() leaves .noinstr.text section
  vmlinux.o: warning: objtool: svm_vcpu_enter_exit+0x85: call to context_tracking_guest_exit() leaves .noinstr.text section

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/dc93f45abdec90c171108b4b590b7fff5790963c.1681320026.git.jpoimboe@kernel.org
---
 include/linux/context_tracking.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index d4afa85..5ae3abd 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -97,7 +97,7 @@ static inline int exception_enter(void) { return 0; }
 static inline void exception_exit(enum ctx_state prev_ctx) { }
 static inline int ct_state(void) { return -1; }
 static __always_inline bool context_tracking_guest_enter(void) { return false; }
-static inline void context_tracking_guest_exit(void) { }
+static __always_inline void context_tracking_guest_exit(void) { }
 #define CT_WARN_ON(cond) do { } while (0)
 #endif /* !CONFIG_CONTEXT_TRACKING_USER */
 

[tip: objtool/core] lkdtm/stackleak: Fix noinstr violation

[tip-bot2 for Josh Poimboeuf]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     f571da059f86fd9d432aea32c9c7e5aaa53245d8
Gitweb:        https://git.kernel.org/tip/f571da059f86fd9d432aea32c9c7e5aaa53245d8
Author:        Josh Poimboeuf <jpoimboe@kernel.org>
AuthorDate:    Wed, 12 Apr 2023 10:24:08 -07:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 14 Apr 2023 16:08:26 +02:00

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@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/ee5209f53aa0a62aea58be18f2b78b17606779a6.1681320026.git.jpoimboe@kernel.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 025b133..f1d0221 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 @@ out:
 	} else {
 		pr_info("OK: the rest of the thread stack is properly erased\n");
 	}
+	instrumentation_end();
 }
 
 static void lkdtm_STACKLEAK_ERASING(void)

[tip: objtool/core] sched: Fix KCSAN noinstr violation

[tip-bot2 for Josh Poimboeuf]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     e0b081d17a9f4e5c0cbb0e5fbeb1abe3de0f7e4e
Gitweb:        https://git.kernel.org/tip/e0b081d17a9f4e5c0cbb0e5fbeb1abe3de0f7e4e
Author:        Josh Poimboeuf <jpoimboe@kernel.org>
AuthorDate:    Wed, 12 Apr 2023 10:24:07 -07:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 14 Apr 2023 16:08:26 +02:00

sched: Fix KCSAN noinstr violation

With KCSAN enabled, end_of_stack() can get out-of-lined.  Force it
inline.

Fixes the following warnings:

  vmlinux.o: warning: objtool: check_stackleak_irqoff+0x2b: call to end_of_stack() leaves .noinstr.text section

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/cc1b4d73d3a428a00d206242a68fdf99a934ca7b.1681320026.git.jpoimboe@kernel.org
---
 include/linux/sched/task_stack.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h
index 5e799a4..f158b02 100644
--- a/include/linux/sched/task_stack.h
+++ b/include/linux/sched/task_stack.h
@@ -23,7 +23,7 @@ static __always_inline void *task_stack_page(const struct task_struct *task)
 
 #define setup_thread_stack(new,old)	do { } while(0)
 
-static inline unsigned long *end_of_stack(const struct task_struct *task)
+static __always_inline unsigned long *end_of_stack(const struct task_struct *task)
 {
 #ifdef CONFIG_STACK_GROWSUP
 	return (unsigned long *)((unsigned long)task->stack + THREAD_SIZE) - 1;