[PATCH 1/4] kasan: mark addr_has_metadata __always_inline

[PATCH 1/4] kasan: mark addr_has_metadata __always_inline

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

When the compiler decides not to inline this function, objdump
complains about incorrect UACCESS state:

mm/kasan/generic.o: warning: objtool: __asan_load2+0x11: call to addr_has_metadata() with UACCESS enabled

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 mm/kasan/kasan.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 3231314e071f..9377b0789edc 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -297,7 +297,7 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
 		<< KASAN_SHADOW_SCALE_SHIFT);
 }
 
-static inline bool addr_has_metadata(const void *addr)
+static __always_inline bool addr_has_metadata(const void *addr)
 {
 	return (kasan_reset_tag(addr) >=
 		kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
@@ -316,7 +316,7 @@ bool kasan_check_range(unsigned long addr, size_t size, bool write,
 
 #else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
 
-static inline bool addr_has_metadata(const void *addr)
+static __always_inline bool addr_has_metadata(const void *addr)
 {
 	return (is_vmalloc_addr(addr) || virt_addr_valid(addr));
 }
-- 
2.39.1

[PATCH 2/4] kmsan: disable ftrace in kmsan core code

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

objtool warns about some suspicous code inside of kmsan:

vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_n+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_n+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_1+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_1+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_2+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_2+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_4+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_4+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_8+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_8+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_instrument_asm_store+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_chain_origin+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_poison_alloca+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_warning+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: __msan_get_context_state+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: kmsan_copy_to_user+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: kmsan_unpoison_memory+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: kmsan_unpoison_entry_regs+0x4: call to __fentry__() with UACCESS enabled
vmlinux.o: warning: objtool: kmsan_report+0x4: call to __fentry__() with UACCESS enabled

Similar code already exists in kasan, which avoids this by skipping
ftrace annotations, so do the same thing here.

Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 mm/kmsan/Makefile | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/kmsan/Makefile b/mm/kmsan/Makefile
index 98eab2856626..389fd767a11f 100644
--- a/mm/kmsan/Makefile
+++ b/mm/kmsan/Makefile
@@ -16,6 +16,14 @@ CC_FLAGS_KMSAN_RUNTIME += -DDISABLE_BRANCH_PROFILING
 
 CFLAGS_REMOVE.o = $(CC_FLAGS_FTRACE)
 
+# Disable ftrace to avoid recursion.
+CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_hooks.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_init.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_instrumentation.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_shadow.o = $(CC_FLAGS_FTRACE)
+
 CFLAGS_core.o := $(CC_FLAGS_KMSAN_RUNTIME)
 CFLAGS_hooks.o := $(CC_FLAGS_KMSAN_RUNTIME)
 CFLAGS_init.o := $(CC_FLAGS_KMSAN_RUNTIME)
-- 
2.39.1

Re: [PATCH 2/4] kmsan: disable ftrace in kmsan core code

[Marco Elver]

On Wed, 8 Feb 2023 at 17:40, Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> objtool warns about some suspicous code inside of kmsan:
>
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_n+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_n+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_1+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_1+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_2+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_2+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_4+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_4+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_load_8+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_metadata_ptr_for_store_8+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_instrument_asm_store+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_chain_origin+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_poison_alloca+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_warning+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: __msan_get_context_state+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: kmsan_copy_to_user+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: kmsan_unpoison_memory+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: kmsan_unpoison_entry_regs+0x4: call to __fentry__() with UACCESS enabled
> vmlinux.o: warning: objtool: kmsan_report+0x4: call to __fentry__() with UACCESS enabled
>
> Similar code already exists in kasan, which avoids this by skipping
> ftrace annotations, so do the same thing here.
>
> Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  mm/kmsan/Makefile | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/mm/kmsan/Makefile b/mm/kmsan/Makefile
> index 98eab2856626..389fd767a11f 100644
> --- a/mm/kmsan/Makefile
> +++ b/mm/kmsan/Makefile
> @@ -16,6 +16,14 @@ CC_FLAGS_KMSAN_RUNTIME += -DDISABLE_BRANCH_PROFILING
>
>  CFLAGS_REMOVE.o = $(CC_FLAGS_FTRACE)

That means this CFLAGS_REMOVE.o didn't work, right? Can it be removed?

> +# Disable ftrace to avoid recursion.
> +CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_hooks.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_init.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_instrumentation.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_shadow.o = $(CC_FLAGS_FTRACE)
> +
>  CFLAGS_core.o := $(CC_FLAGS_KMSAN_RUNTIME)
>  CFLAGS_hooks.o := $(CC_FLAGS_KMSAN_RUNTIME)
>  CFLAGS_init.o := $(CC_FLAGS_KMSAN_RUNTIME)
> --
> 2.39.1
>

Re: [PATCH 2/4] kmsan: disable ftrace in kmsan core code

[Arnd Bergmann]

On Wed, Feb 8, 2023, at 18:00, Marco Elver wrote:

>>  CFLAGS_REMOVE.o = $(CC_FLAGS_FTRACE)
>
> That means this CFLAGS_REMOVE.o didn't work, right? Can it be removed?
>

Ah, I missed this. Adjusted the patch and description accordingly.

    Arnd

Re: [PATCH 2/4] kmsan: disable ftrace in kmsan core code

[Alexander Potapenko]

On Wed, Feb 8, 2023 at 8:32 PM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Wed, Feb 8, 2023, at 18:00, Marco Elver wrote:
>
> >>  CFLAGS_REMOVE.o = $(CC_FLAGS_FTRACE)
> >
> > That means this CFLAGS_REMOVE.o didn't work, right? Can it be removed?
> >
>
> Ah, I missed this. Adjusted the patch and description accordingly.
>
>     Arnd

Acked-by: Alexander Potapenko <glider@google.com>

(assuming you did, b/c I couldn't find the new version)

Re: [PATCH 1/4] kasan: mark addr_has_metadata __always_inline

[Marco Elver]

On Wed, 8 Feb 2023 at 17:40, Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> When the compiler decides not to inline this function, objdump
> complains about incorrect UACCESS state:
>
> mm/kasan/generic.o: warning: objtool: __asan_load2+0x11: call to addr_has_metadata() with UACCESS enabled
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Marco Elver <elver@google.com>

> ---
>  mm/kasan/kasan.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 3231314e071f..9377b0789edc 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -297,7 +297,7 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
>                 << KASAN_SHADOW_SCALE_SHIFT);
>  }
>
> -static inline bool addr_has_metadata(const void *addr)
> +static __always_inline bool addr_has_metadata(const void *addr)
>  {
>         return (kasan_reset_tag(addr) >=
>                 kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
> @@ -316,7 +316,7 @@ bool kasan_check_range(unsigned long addr, size_t size, bool write,
>
>  #else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
>
> -static inline bool addr_has_metadata(const void *addr)
> +static __always_inline bool addr_has_metadata(const void *addr)
>  {
>         return (is_vmalloc_addr(addr) || virt_addr_valid(addr));
>  }
> --
> 2.39.1
>

Re: [PATCH 1/4] kasan: mark addr_has_metadata __always_inline

[Peter Zijlstra]

On Wed, Feb 08, 2023 at 05:39:55PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> When the compiler decides not to inline this function, objdump
> complains about incorrect UACCESS state:
> 
> mm/kasan/generic.o: warning: objtool: __asan_load2+0x11: call to addr_has_metadata() with UACCESS enabled
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

> ---
>  mm/kasan/kasan.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 3231314e071f..9377b0789edc 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -297,7 +297,7 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
>  		<< KASAN_SHADOW_SCALE_SHIFT);
>  }
>  
> -static inline bool addr_has_metadata(const void *addr)
> +static __always_inline bool addr_has_metadata(const void *addr)
>  {
>  	return (kasan_reset_tag(addr) >=
>  		kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
> @@ -316,7 +316,7 @@ bool kasan_check_range(unsigned long addr, size_t size, bool write,
>  
>  #else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
>  
> -static inline bool addr_has_metadata(const void *addr)
> +static __always_inline bool addr_has_metadata(const void *addr)
>  {
>  	return (is_vmalloc_addr(addr) || virt_addr_valid(addr));
>  }
> -- 
> 2.39.1
> 

Re: [PATCH 1/4] kasan: mark addr_has_metadata __always_inline

[Josh Poimboeuf]

On Wed, Feb 08, 2023 at 05:39:55PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> When the compiler decides not to inline this function, objdump

"objdump" -> "objtool" here and in patch subject.

-- 
Josh

Re: [PATCH 1/4] kasan: mark addr_has_metadata __always_inline

[Andrey Konovalov]

On Wed, Feb 8, 2023 at 5:40 PM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> When the compiler decides not to inline this function, objdump
> complains about incorrect UACCESS state:
>
> mm/kasan/generic.o: warning: objtool: __asan_load2+0x11: call to addr_has_metadata() with UACCESS enabled
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  mm/kasan/kasan.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index 3231314e071f..9377b0789edc 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -297,7 +297,7 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
>                 << KASAN_SHADOW_SCALE_SHIFT);
>  }
>
> -static inline bool addr_has_metadata(const void *addr)
> +static __always_inline bool addr_has_metadata(const void *addr)
>  {
>         return (kasan_reset_tag(addr) >=
>                 kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
> @@ -316,7 +316,7 @@ bool kasan_check_range(unsigned long addr, size_t size, bool write,
>
>  #else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
>
> -static inline bool addr_has_metadata(const void *addr)
> +static __always_inline bool addr_has_metadata(const void *addr)
>  {
>         return (is_vmalloc_addr(addr) || virt_addr_valid(addr));
>  }
> --
> 2.39.1
>

Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>

Thanks!