[v12,20/25] kasan, arm64: add brk handler for inline instrumentation
diff mbox series

Message ID e825441eda1dbbbb7f583f826a66c94e6f88316a.1543337629.git.andreyknvl@google.com
State Not Applicable, archived
Headers show
Series
  • kasan: add software tag-based mode for arm64
Related show

Commit Message

Andrey Konovalov Nov. 27, 2018, 4:55 p.m. UTC
Tag-based KASAN inline instrumentation mode (which embeds checks of shadow
memory into the generated code, instead of inserting a callback) generates
a brk instruction when a tag mismatch is detected.

This commit adds a tag-based KASAN specific brk handler, that decodes the
immediate value passed to the brk instructions (to extract information
about the memory access that triggered the mismatch), reads the register
values (x0 contains the guilty address) and reports the bug.

Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 arch/arm64/include/asm/brk-imm.h |  2 +
 arch/arm64/kernel/traps.c        | 68 +++++++++++++++++++++++++++++++-
 include/linux/kasan.h            |  3 ++
 3 files changed, 71 insertions(+), 2 deletions(-)

Comments

Will Deacon Nov. 29, 2018, 6:01 p.m. UTC | #1
On Tue, Nov 27, 2018 at 05:55:38PM +0100, Andrey Konovalov wrote:
> Tag-based KASAN inline instrumentation mode (which embeds checks of shadow
> memory into the generated code, instead of inserting a callback) generates
> a brk instruction when a tag mismatch is detected.
> 
> This commit adds a tag-based KASAN specific brk handler, that decodes the
> immediate value passed to the brk instructions (to extract information
> about the memory access that triggered the mismatch), reads the register
> values (x0 contains the guilty address) and reports the bug.
> 
> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>  arch/arm64/include/asm/brk-imm.h |  2 +
>  arch/arm64/kernel/traps.c        | 68 +++++++++++++++++++++++++++++++-
>  include/linux/kasan.h            |  3 ++
>  3 files changed, 71 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h
> index ed693c5bcec0..2945fe6cd863 100644
> --- a/arch/arm64/include/asm/brk-imm.h
> +++ b/arch/arm64/include/asm/brk-imm.h
> @@ -16,10 +16,12 @@
>   * 0x400: for dynamic BRK instruction
>   * 0x401: for compile time BRK instruction
>   * 0x800: kernel-mode BUG() and WARN() traps
> + * 0x9xx: tag-based KASAN trap (allowed values 0x900 - 0x9ff)
>   */
>  #define FAULT_BRK_IMM			0x100
>  #define KGDB_DYN_DBG_BRK_IMM		0x400
>  #define KGDB_COMPILED_DBG_BRK_IMM	0x401
>  #define BUG_BRK_IMM			0x800
> +#define KASAN_BRK_IMM			0x900
>  
>  #endif
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 5f4d9acb32f5..04bdc53716ef 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -35,6 +35,7 @@
>  #include <linux/sizes.h>
>  #include <linux/syscalls.h>
>  #include <linux/mm_types.h>
> +#include <linux/kasan.h>
>  
>  #include <asm/atomic.h>
>  #include <asm/bug.h>
> @@ -284,10 +285,14 @@ void arm64_notify_die(const char *str, struct pt_regs *regs,
>  	}
>  }
>  
> -void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> +void __arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
>  {
>  	regs->pc += size;
> +}
>  
> +void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> +{
> +	__arm64_skip_faulting_instruction(regs, size);
>  	/*
>  	 * If we were single stepping, we want to get the step exception after
>  	 * we return from the trap.
> @@ -959,7 +964,7 @@ static int bug_handler(struct pt_regs *regs, unsigned int esr)
>  	}
>  
>  	/* If thread survives, skip over the BUG instruction and continue: */
> -	arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
> +	__arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);

Why do you want to avoid the single-step logic here? Given that we're
skipping over the brk instruction, why wouldn't you want that to trigger
a step exception if single-step is enabled?

Will
Andrey Konovalov Dec. 6, 2018, 10:31 a.m. UTC | #2
On Thu, Nov 29, 2018 at 7:01 PM Will Deacon <will.deacon@arm.com> wrote:
>
> On Tue, Nov 27, 2018 at 05:55:38PM +0100, Andrey Konovalov wrote:
> > Tag-based KASAN inline instrumentation mode (which embeds checks of shadow
> > memory into the generated code, instead of inserting a callback) generates
> > a brk instruction when a tag mismatch is detected.
> >
> > This commit adds a tag-based KASAN specific brk handler, that decodes the
> > immediate value passed to the brk instructions (to extract information
> > about the memory access that triggered the mismatch), reads the register
> > values (x0 contains the guilty address) and reports the bug.
> >
> > Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> > Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > ---
> >  arch/arm64/include/asm/brk-imm.h |  2 +
> >  arch/arm64/kernel/traps.c        | 68 +++++++++++++++++++++++++++++++-
> >  include/linux/kasan.h            |  3 ++
> >  3 files changed, 71 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h
> > index ed693c5bcec0..2945fe6cd863 100644
> > --- a/arch/arm64/include/asm/brk-imm.h
> > +++ b/arch/arm64/include/asm/brk-imm.h
> > @@ -16,10 +16,12 @@
> >   * 0x400: for dynamic BRK instruction
> >   * 0x401: for compile time BRK instruction
> >   * 0x800: kernel-mode BUG() and WARN() traps
> > + * 0x9xx: tag-based KASAN trap (allowed values 0x900 - 0x9ff)
> >   */
> >  #define FAULT_BRK_IMM                        0x100
> >  #define KGDB_DYN_DBG_BRK_IMM         0x400
> >  #define KGDB_COMPILED_DBG_BRK_IMM    0x401
> >  #define BUG_BRK_IMM                  0x800
> > +#define KASAN_BRK_IMM                        0x900
> >
> >  #endif
> > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> > index 5f4d9acb32f5..04bdc53716ef 100644
> > --- a/arch/arm64/kernel/traps.c
> > +++ b/arch/arm64/kernel/traps.c
> > @@ -35,6 +35,7 @@
> >  #include <linux/sizes.h>
> >  #include <linux/syscalls.h>
> >  #include <linux/mm_types.h>
> > +#include <linux/kasan.h>
> >
> >  #include <asm/atomic.h>
> >  #include <asm/bug.h>
> > @@ -284,10 +285,14 @@ void arm64_notify_die(const char *str, struct pt_regs *regs,
> >       }
> >  }
> >
> > -void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> > +void __arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> >  {
> >       regs->pc += size;
> > +}
> >
> > +void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> > +{
> > +     __arm64_skip_faulting_instruction(regs, size);
> >       /*
> >        * If we were single stepping, we want to get the step exception after
> >        * we return from the trap.
> > @@ -959,7 +964,7 @@ static int bug_handler(struct pt_regs *regs, unsigned int esr)
> >       }
> >
> >       /* If thread survives, skip over the BUG instruction and continue: */
> > -     arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
> > +     __arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
>
> Why do you want to avoid the single-step logic here? Given that we're
> skipping over the brk instruction, why wouldn't you want that to trigger
> a step exception if single-step is enabled?

I was asked to do that, see the discussion here:

https://www.spinics.net/lists/linux-mm/msg146575.html
https://www.spinics.net/lists/linux-mm/msg148215.html
https://www.spinics.net/lists/linux-mm/msg148367.html
Will Deacon Dec. 6, 2018, 11:11 a.m. UTC | #3
On Thu, Dec 06, 2018 at 11:31:43AM +0100, Andrey Konovalov wrote:
> On Thu, Nov 29, 2018 at 7:01 PM Will Deacon <will.deacon@arm.com> wrote:
> >
> > On Tue, Nov 27, 2018 at 05:55:38PM +0100, Andrey Konovalov wrote:
> > > Tag-based KASAN inline instrumentation mode (which embeds checks of shadow
> > > memory into the generated code, instead of inserting a callback) generates
> > > a brk instruction when a tag mismatch is detected.
> > >
> > > This commit adds a tag-based KASAN specific brk handler, that decodes the
> > > immediate value passed to the brk instructions (to extract information
> > > about the memory access that triggered the mismatch), reads the register
> > > values (x0 contains the guilty address) and reports the bug.
> > >
> > > Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> > > Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > ---
> > >  arch/arm64/include/asm/brk-imm.h |  2 +
> > >  arch/arm64/kernel/traps.c        | 68 +++++++++++++++++++++++++++++++-
> > >  include/linux/kasan.h            |  3 ++
> > >  3 files changed, 71 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h
> > > index ed693c5bcec0..2945fe6cd863 100644
> > > --- a/arch/arm64/include/asm/brk-imm.h
> > > +++ b/arch/arm64/include/asm/brk-imm.h
> > > @@ -16,10 +16,12 @@
> > >   * 0x400: for dynamic BRK instruction
> > >   * 0x401: for compile time BRK instruction
> > >   * 0x800: kernel-mode BUG() and WARN() traps
> > > + * 0x9xx: tag-based KASAN trap (allowed values 0x900 - 0x9ff)
> > >   */
> > >  #define FAULT_BRK_IMM                        0x100
> > >  #define KGDB_DYN_DBG_BRK_IMM         0x400
> > >  #define KGDB_COMPILED_DBG_BRK_IMM    0x401
> > >  #define BUG_BRK_IMM                  0x800
> > > +#define KASAN_BRK_IMM                        0x900
> > >
> > >  #endif
> > > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> > > index 5f4d9acb32f5..04bdc53716ef 100644
> > > --- a/arch/arm64/kernel/traps.c
> > > +++ b/arch/arm64/kernel/traps.c
> > > @@ -35,6 +35,7 @@
> > >  #include <linux/sizes.h>
> > >  #include <linux/syscalls.h>
> > >  #include <linux/mm_types.h>
> > > +#include <linux/kasan.h>
> > >
> > >  #include <asm/atomic.h>
> > >  #include <asm/bug.h>
> > > @@ -284,10 +285,14 @@ void arm64_notify_die(const char *str, struct pt_regs *regs,
> > >       }
> > >  }
> > >
> > > -void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> > > +void __arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> > >  {
> > >       regs->pc += size;
> > > +}
> > >
> > > +void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> > > +{
> > > +     __arm64_skip_faulting_instruction(regs, size);
> > >       /*
> > >        * If we were single stepping, we want to get the step exception after
> > >        * we return from the trap.
> > > @@ -959,7 +964,7 @@ static int bug_handler(struct pt_regs *regs, unsigned int esr)
> > >       }
> > >
> > >       /* If thread survives, skip over the BUG instruction and continue: */
> > > -     arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
> > > +     __arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
> >
> > Why do you want to avoid the single-step logic here? Given that we're
> > skipping over the brk instruction, why wouldn't you want that to trigger
> > a step exception if single-step is enabled?
> 
> I was asked to do that, see the discussion here:
> 
> https://www.spinics.net/lists/linux-mm/msg146575.html
> https://www.spinics.net/lists/linux-mm/msg148215.html
> https://www.spinics.net/lists/linux-mm/msg148367.html

Aha, but we subsequently fixed the underlying problem in commit
9478f1927e6e ("arm64: only advance singlestep for user instruction traps").
You were on cc, but I appreciate it's not clear that it was related to this.

Anyway, you can just call arm64_skip_faulting_instruction() as you were
doing and there's no need for this refactoring.

Please could you spin a new version so that akpm can replace the one which
he has queued?

Thanks,

Will
Andrey Konovalov Dec. 6, 2018, 12:25 p.m. UTC | #4
On Thu, Dec 6, 2018 at 12:10 PM Will Deacon <will.deacon@arm.com> wrote:
>
> On Thu, Dec 06, 2018 at 11:31:43AM +0100, Andrey Konovalov wrote:
> > On Thu, Nov 29, 2018 at 7:01 PM Will Deacon <will.deacon@arm.com> wrote:
> > >
> > > On Tue, Nov 27, 2018 at 05:55:38PM +0100, Andrey Konovalov wrote:
> > > > Tag-based KASAN inline instrumentation mode (which embeds checks of shadow
> > > > memory into the generated code, instead of inserting a callback) generates
> > > > a brk instruction when a tag mismatch is detected.
> > > >
> > > > This commit adds a tag-based KASAN specific brk handler, that decodes the
> > > > immediate value passed to the brk instructions (to extract information
> > > > about the memory access that triggered the mismatch), reads the register
> > > > values (x0 contains the guilty address) and reports the bug.
> > > >
> > > > Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> > > > Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
> > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > > ---
> > > >  arch/arm64/include/asm/brk-imm.h |  2 +
> > > >  arch/arm64/kernel/traps.c        | 68 +++++++++++++++++++++++++++++++-
> > > >  include/linux/kasan.h            |  3 ++
> > > >  3 files changed, 71 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h
> > > > index ed693c5bcec0..2945fe6cd863 100644
> > > > --- a/arch/arm64/include/asm/brk-imm.h
> > > > +++ b/arch/arm64/include/asm/brk-imm.h
> > > > @@ -16,10 +16,12 @@
> > > >   * 0x400: for dynamic BRK instruction
> > > >   * 0x401: for compile time BRK instruction
> > > >   * 0x800: kernel-mode BUG() and WARN() traps
> > > > + * 0x9xx: tag-based KASAN trap (allowed values 0x900 - 0x9ff)
> > > >   */
> > > >  #define FAULT_BRK_IMM                        0x100
> > > >  #define KGDB_DYN_DBG_BRK_IMM         0x400
> > > >  #define KGDB_COMPILED_DBG_BRK_IMM    0x401
> > > >  #define BUG_BRK_IMM                  0x800
> > > > +#define KASAN_BRK_IMM                        0x900
> > > >
> > > >  #endif
> > > > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> > > > index 5f4d9acb32f5..04bdc53716ef 100644
> > > > --- a/arch/arm64/kernel/traps.c
> > > > +++ b/arch/arm64/kernel/traps.c
> > > > @@ -35,6 +35,7 @@
> > > >  #include <linux/sizes.h>
> > > >  #include <linux/syscalls.h>
> > > >  #include <linux/mm_types.h>
> > > > +#include <linux/kasan.h>
> > > >
> > > >  #include <asm/atomic.h>
> > > >  #include <asm/bug.h>
> > > > @@ -284,10 +285,14 @@ void arm64_notify_die(const char *str, struct pt_regs *regs,
> > > >       }
> > > >  }
> > > >
> > > > -void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> > > > +void __arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> > > >  {
> > > >       regs->pc += size;
> > > > +}
> > > >
> > > > +void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
> > > > +{
> > > > +     __arm64_skip_faulting_instruction(regs, size);
> > > >       /*
> > > >        * If we were single stepping, we want to get the step exception after
> > > >        * we return from the trap.
> > > > @@ -959,7 +964,7 @@ static int bug_handler(struct pt_regs *regs, unsigned int esr)
> > > >       }
> > > >
> > > >       /* If thread survives, skip over the BUG instruction and continue: */
> > > > -     arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
> > > > +     __arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
> > >
> > > Why do you want to avoid the single-step logic here? Given that we're
> > > skipping over the brk instruction, why wouldn't you want that to trigger
> > > a step exception if single-step is enabled?
> >
> > I was asked to do that, see the discussion here:
> >
> > https://www.spinics.net/lists/linux-mm/msg146575.html
> > https://www.spinics.net/lists/linux-mm/msg148215.html
> > https://www.spinics.net/lists/linux-mm/msg148367.html
>
> Aha, but we subsequently fixed the underlying problem in commit
> 9478f1927e6e ("arm64: only advance singlestep for user instruction traps").
> You were on cc, but I appreciate it's not clear that it was related to this.

Sorry, missed that patch.

> Anyway, you can just call arm64_skip_faulting_instruction() as you were
> doing and there's no need for this refactoring.
>
> Please could you spin a new version so that akpm can replace the one which
> he has queued?

Done. Thanks!

Patch
diff mbox series

diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h
index ed693c5bcec0..2945fe6cd863 100644
--- a/arch/arm64/include/asm/brk-imm.h
+++ b/arch/arm64/include/asm/brk-imm.h
@@ -16,10 +16,12 @@ 
  * 0x400: for dynamic BRK instruction
  * 0x401: for compile time BRK instruction
  * 0x800: kernel-mode BUG() and WARN() traps
+ * 0x9xx: tag-based KASAN trap (allowed values 0x900 - 0x9ff)
  */
 #define FAULT_BRK_IMM			0x100
 #define KGDB_DYN_DBG_BRK_IMM		0x400
 #define KGDB_COMPILED_DBG_BRK_IMM	0x401
 #define BUG_BRK_IMM			0x800
+#define KASAN_BRK_IMM			0x900
 
 #endif
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 5f4d9acb32f5..04bdc53716ef 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -35,6 +35,7 @@ 
 #include <linux/sizes.h>
 #include <linux/syscalls.h>
 #include <linux/mm_types.h>
+#include <linux/kasan.h>
 
 #include <asm/atomic.h>
 #include <asm/bug.h>
@@ -284,10 +285,14 @@  void arm64_notify_die(const char *str, struct pt_regs *regs,
 	}
 }
 
-void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
+void __arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
 {
 	regs->pc += size;
+}
 
+void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
+{
+	__arm64_skip_faulting_instruction(regs, size);
 	/*
 	 * If we were single stepping, we want to get the step exception after
 	 * we return from the trap.
@@ -959,7 +964,7 @@  static int bug_handler(struct pt_regs *regs, unsigned int esr)
 	}
 
 	/* If thread survives, skip over the BUG instruction and continue: */
-	arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
+	__arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
 	return DBG_HOOK_HANDLED;
 }
 
@@ -969,6 +974,58 @@  static struct break_hook bug_break_hook = {
 	.fn = bug_handler,
 };
 
+#ifdef CONFIG_KASAN_SW_TAGS
+
+#define KASAN_ESR_RECOVER	0x20
+#define KASAN_ESR_WRITE	0x10
+#define KASAN_ESR_SIZE_MASK	0x0f
+#define KASAN_ESR_SIZE(esr)	(1 << ((esr) & KASAN_ESR_SIZE_MASK))
+
+static int kasan_handler(struct pt_regs *regs, unsigned int esr)
+{
+	bool recover = esr & KASAN_ESR_RECOVER;
+	bool write = esr & KASAN_ESR_WRITE;
+	size_t size = KASAN_ESR_SIZE(esr);
+	u64 addr = regs->regs[0];
+	u64 pc = regs->pc;
+
+	if (user_mode(regs))
+		return DBG_HOOK_ERROR;
+
+	kasan_report(addr, size, write, pc);
+
+	/*
+	 * The instrumentation allows to control whether we can proceed after
+	 * a crash was detected. This is done by passing the -recover flag to
+	 * the compiler. Disabling recovery allows to generate more compact
+	 * code.
+	 *
+	 * Unfortunately disabling recovery doesn't work for the kernel right
+	 * now. KASAN reporting is disabled in some contexts (for example when
+	 * the allocator accesses slab object metadata; this is controlled by
+	 * current->kasan_depth). All these accesses are detected by the tool,
+	 * even though the reports for them are not printed.
+	 *
+	 * This is something that might be fixed at some point in the future.
+	 */
+	if (!recover)
+		die("Oops - KASAN", regs, 0);
+
+	/* If thread survives, skip over the brk instruction and continue: */
+	__arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
+	return DBG_HOOK_HANDLED;
+}
+
+#define KASAN_ESR_VAL (0xf2000000 | KASAN_BRK_IMM)
+#define KASAN_ESR_MASK 0xffffff00
+
+static struct break_hook kasan_break_hook = {
+	.esr_val = KASAN_ESR_VAL,
+	.esr_mask = KASAN_ESR_MASK,
+	.fn = kasan_handler,
+};
+#endif
+
 /*
  * Initial handler for AArch64 BRK exceptions
  * This handler only used until debug_traps_init().
@@ -976,6 +1033,10 @@  static struct break_hook bug_break_hook = {
 int __init early_brk64(unsigned long addr, unsigned int esr,
 		struct pt_regs *regs)
 {
+#ifdef CONFIG_KASAN_SW_TAGS
+	if ((esr & KASAN_ESR_MASK) == KASAN_ESR_VAL)
+		return kasan_handler(regs, esr) != DBG_HOOK_HANDLED;
+#endif
 	return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
 }
 
@@ -983,4 +1044,7 @@  int __init early_brk64(unsigned long addr, unsigned int esr,
 void __init trap_init(void)
 {
 	register_break_hook(&bug_break_hook);
+#ifdef CONFIG_KASAN_SW_TAGS
+	register_break_hook(&kasan_break_hook);
+#endif
 }
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index a477ce2abdc9..8da7b7a4397a 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -173,6 +173,9 @@  void kasan_init_tags(void);
 
 void *kasan_reset_tag(const void *addr);
 
+void kasan_report(unsigned long addr, size_t size,
+		bool is_write, unsigned long ip);
+
 #else /* CONFIG_KASAN_SW_TAGS */
 
 static inline void kasan_init_tags(void) { }