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Message-ID: <CANpmjNMznQsC6ftzy7MCa7uQVCFv=MFg6JW28QdnGPyzFEZn5A@mail.gmail.com>
Date: Thu, 12 Jan 2023 12:34:37 +0100
From: Marco Elver <elver@...gle.com>
To: Alexander Potapenko <glider@...gle.com>
Cc: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
peterz@...radead.org, mingo@...hat.com, dvyukov@...gle.com,
linux-mm@...ck.org, kasan-dev@...glegroups.com,
kernel test robot <lkp@...el.com>,
Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCH] kmsan: silence -Wmissing-prototypes warnings
On Thu, 12 Jan 2023 at 11:31, Alexander Potapenko <glider@...gle.com> wrote:
>
> When building the kernel with W=1, the compiler reports numerous
> warnings about the missing prototypes for KMSAN instrumentation hooks.
>
> Because these functions are not supposed to be called explicitly by the
> kernel code (calls to them are emitted by the compiler), they do not
> have to be declared in the headers. Instead, we add forward declarations
> right before the definitions to silence the warnings produced by
> -Wmissing-prototypes.
>
> Reported-by: kernel test robot <lkp@...el.com>
> Link: https://lore.kernel.org/lkml/202301020356.dFruA4I5-lkp@intel.com/T/
> Reported-by: Vlastimil Babka <vbabka@...e.cz>
> Suggested-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Alexander Potapenko <glider@...gle.com>
Reviewed-by: Marco Elver <elver@...gle.com>
> ---
> mm/kmsan/instrumentation.c | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/mm/kmsan/instrumentation.c b/mm/kmsan/instrumentation.c
> index 770fe02904f36..cf12e9616b243 100644
> --- a/mm/kmsan/instrumentation.c
> +++ b/mm/kmsan/instrumentation.c
> @@ -38,7 +38,15 @@ get_shadow_origin_ptr(void *addr, u64 size, bool store)
> return ret;
> }
>
> +/*
> + * KMSAN instrumentation functions follow. They are not declared elsewhere in
> + * the kernel code, so they are preceded by prototypes, to silence
> + * -Wmissing-prototypes warnings.
> + */
> +
> /* Get shadow and origin pointers for a memory load with non-standard size. */
> +struct shadow_origin_ptr __msan_metadata_ptr_for_load_n(void *addr,
> + uintptr_t size);
> struct shadow_origin_ptr __msan_metadata_ptr_for_load_n(void *addr,
> uintptr_t size)
> {
> @@ -47,6 +55,8 @@ struct shadow_origin_ptr __msan_metadata_ptr_for_load_n(void *addr,
> EXPORT_SYMBOL(__msan_metadata_ptr_for_load_n);
>
> /* Get shadow and origin pointers for a memory store with non-standard size. */
> +struct shadow_origin_ptr __msan_metadata_ptr_for_store_n(void *addr,
> + uintptr_t size);
> struct shadow_origin_ptr __msan_metadata_ptr_for_store_n(void *addr,
> uintptr_t size)
> {
> @@ -59,12 +69,16 @@ EXPORT_SYMBOL(__msan_metadata_ptr_for_store_n);
> * with fixed size.
> */
> #define DECLARE_METADATA_PTR_GETTER(size) \
> + struct shadow_origin_ptr __msan_metadata_ptr_for_load_##size( \
> + void *addr); \
> struct shadow_origin_ptr __msan_metadata_ptr_for_load_##size( \
> void *addr) \
> { \
> return get_shadow_origin_ptr(addr, size, /*store*/ false); \
> } \
> EXPORT_SYMBOL(__msan_metadata_ptr_for_load_##size); \
> + struct shadow_origin_ptr __msan_metadata_ptr_for_store_##size( \
> + void *addr); \
> struct shadow_origin_ptr __msan_metadata_ptr_for_store_##size( \
> void *addr) \
> { \
> @@ -86,6 +100,7 @@ DECLARE_METADATA_PTR_GETTER(8);
> * entering or leaving IRQ. We omit the check for kmsan_in_runtime() to ensure
> * the memory written to in these cases is also marked as initialized.
> */
> +void __msan_instrument_asm_store(void *addr, uintptr_t size);
> void __msan_instrument_asm_store(void *addr, uintptr_t size)
> {
> unsigned long ua_flags;
> @@ -138,6 +153,7 @@ static inline void set_retval_metadata(u64 shadow, depot_stack_handle_t origin)
> }
>
> /* Handle llvm.memmove intrinsic. */
> +void *__msan_memmove(void *dst, const void *src, uintptr_t n);
> void *__msan_memmove(void *dst, const void *src, uintptr_t n)
> {
> depot_stack_handle_t origin;
> @@ -162,6 +178,7 @@ void *__msan_memmove(void *dst, const void *src, uintptr_t n)
> EXPORT_SYMBOL(__msan_memmove);
>
> /* Handle llvm.memcpy intrinsic. */
> +void *__msan_memcpy(void *dst, const void *src, uintptr_t n);
> void *__msan_memcpy(void *dst, const void *src, uintptr_t n)
> {
> depot_stack_handle_t origin;
> @@ -188,6 +205,7 @@ void *__msan_memcpy(void *dst, const void *src, uintptr_t n)
> EXPORT_SYMBOL(__msan_memcpy);
>
> /* Handle llvm.memset intrinsic. */
> +void *__msan_memset(void *dst, int c, uintptr_t n);
> void *__msan_memset(void *dst, int c, uintptr_t n)
> {
> depot_stack_handle_t origin;
> @@ -217,6 +235,7 @@ EXPORT_SYMBOL(__msan_memset);
> * uninitialized value to memory. When reporting an error, KMSAN unrolls and
> * prints the whole chain of stores that preceded the use of this value.
> */
> +depot_stack_handle_t __msan_chain_origin(depot_stack_handle_t origin);
> depot_stack_handle_t __msan_chain_origin(depot_stack_handle_t origin)
> {
> depot_stack_handle_t ret = 0;
> @@ -237,6 +256,7 @@ depot_stack_handle_t __msan_chain_origin(depot_stack_handle_t origin)
> EXPORT_SYMBOL(__msan_chain_origin);
>
> /* Poison a local variable when entering a function. */
> +void __msan_poison_alloca(void *address, uintptr_t size, char *descr);
> void __msan_poison_alloca(void *address, uintptr_t size, char *descr)
> {
> depot_stack_handle_t handle;
> @@ -272,6 +292,7 @@ void __msan_poison_alloca(void *address, uintptr_t size, char *descr)
> EXPORT_SYMBOL(__msan_poison_alloca);
>
> /* Unpoison a local variable. */
> +void __msan_unpoison_alloca(void *address, uintptr_t size);
> void __msan_unpoison_alloca(void *address, uintptr_t size)
> {
> if (!kmsan_enabled || kmsan_in_runtime())
> @@ -287,6 +308,7 @@ EXPORT_SYMBOL(__msan_unpoison_alloca);
> * Report that an uninitialized value with the given origin was used in a way
> * that constituted undefined behavior.
> */
> +void __msan_warning(u32 origin);
> void __msan_warning(u32 origin)
> {
> if (!kmsan_enabled || kmsan_in_runtime())
> @@ -303,6 +325,7 @@ EXPORT_SYMBOL(__msan_warning);
> * At the beginning of an instrumented function, obtain the pointer to
> * `struct kmsan_context_state` holding the metadata for function parameters.
> */
> +struct kmsan_context_state *__msan_get_context_state(void);
> struct kmsan_context_state *__msan_get_context_state(void)
> {
> return &kmsan_get_context()->cstate;
> --
> 2.39.0.314.g84b9a713c41-goog
>
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