Re: [RFC PATCH 2/4] kmemtrace: SLAB hooks.

[Pekka Enberg]

On Tue, 2008-07-22 at 21:36 +0300, Eduard - Gabriel Munteanu wrote:
> This adds hooks for the SLAB allocator, to allow tracing with kmemtrace.
> 
> Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@xxxxxxxxxxx>
> ---
>  include/linux/slab_def.h |   68 ++++++++++++++++++++++++++++++++++++++------
>  mm/slab.c                |   71 +++++++++++++++++++++++++++++++++++++++++----
>  2 files changed, 123 insertions(+), 16 deletions(-)
> 
> diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
> index 39c3a5e..7555ce9 100644
> --- a/include/linux/slab_def.h
> +++ b/include/linux/slab_def.h
> @@ -14,6 +14,7 @@
>  #include <asm/page.h>		/* kmalloc_sizes.h needs PAGE_SIZE */
>  #include <asm/cache.h>		/* kmalloc_sizes.h needs L1_CACHE_BYTES */
>  #include <linux/compiler.h>
> +#include <linux/kmemtrace.h>
>  
>  /* Size description struct for general caches. */
>  struct cache_sizes {
> @@ -28,8 +29,26 @@ extern struct cache_sizes malloc_sizes[];
>  void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
>  void *__kmalloc(size_t size, gfp_t flags);
>  
> -static inline void *kmalloc(size_t size, gfp_t flags)
> +#ifdef CONFIG_KMEMTRACE
> +extern void *kmem_cache_alloc_notrace(struct kmem_cache *cachep, gfp_t flags);
> +extern size_t slab_buffer_size(struct kmem_cache *cachep);
> +#else
> +static __always_inline void *
> +kmem_cache_alloc_notrace(struct kmem_cache *cachep, gfp_t flags)
>  {
> +	return kmem_cache_alloc(cachep, flags);
> +}
> +static inline size_t slab_buffer_size(struct kmem_cache *cachep)
> +{
> +	return 0;
> +}

You're introducing this to work around the fact that struct kmem_cache
is defined in mm/slab.c? Please note that for kmemcheck we already moved
struct kmem_cache to a header file so we should be able to use the same
approach.

> +#endif
> +
> +static __always_inline void *kmalloc(size_t size, gfp_t flags)
> +{
> +	struct kmem_cache *cachep;
> +	void *ret;
> +
>  	if (__builtin_constant_p(size)) {
>  		int i = 0;
>  
> @@ -50,10 +69,17 @@ static inline void *kmalloc(size_t size, gfp_t flags)
>  found:
>  #ifdef CONFIG_ZONE_DMA
>  		if (flags & GFP_DMA)
> -			return kmem_cache_alloc(malloc_sizes[i].cs_dmacachep,
> -						flags);
> +			cachep = malloc_sizes[i].cs_dmacachep;
> +		else
>  #endif
> -		return kmem_cache_alloc(malloc_sizes[i].cs_cachep, flags);
> +			cachep = malloc_sizes[i].cs_cachep;
> +
> +		ret = kmem_cache_alloc_notrace(cachep, flags);
> +
> +		kmemtrace_mark_alloc(KMEMTRACE_TYPE_KMALLOC, _THIS_IP_, ret,
> +				     size, slab_buffer_size(cachep), flags);
> +
> +		return ret;
>  	}
>  	return __kmalloc(size, flags);
>  }
> @@ -62,8 +88,25 @@ found:
>  extern void *__kmalloc_node(size_t size, gfp_t flags, int node);
>  extern void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
>  
> -static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
> +#ifdef CONFIG_KMEMTRACE
> +extern void *kmem_cache_alloc_node_notrace(struct kmem_cache *cachep,
> +					   gfp_t flags,
> +					   int nodeid);
> +#else
> +static __always_inline void *
> +kmem_cache_alloc_node_notrace(struct kmem_cache *cachep,
> +			      gfp_t flags,
> +			      int nodeid)
> +{
> +	return kmem_cache_alloc_node(cachep, flags, nodeid);
> +}
> +#endif
> +
> +static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
>  {
> +	struct kmem_cache *cachep;
> +	void *ret;
> +
>  	if (__builtin_constant_p(size)) {
>  		int i = 0;
>  
> @@ -84,11 +127,18 @@ static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
>  found:
>  #ifdef CONFIG_ZONE_DMA
>  		if (flags & GFP_DMA)
> -			return kmem_cache_alloc_node(malloc_sizes[i].cs_dmacachep,
> -						flags, node);
> +			cachep = malloc_sizes[i].cs_dmacachep;
> +		else
>  #endif
> -		return kmem_cache_alloc_node(malloc_sizes[i].cs_cachep,
> -						flags, node);
> +			cachep = malloc_sizes[i].cs_cachep;
> +
> +		ret = kmem_cache_alloc_node_notrace(cachep, flags, node);
> +
> +		kmemtrace_mark_alloc_node(KMEMTRACE_TYPE_KMALLOC, _THIS_IP_,
> +					  ret, size, slab_buffer_size(cachep),
> +					  flags, node);
> +
> +		return ret;
>  	}
>  	return __kmalloc_node(size, flags, node);
>  }
> diff --git a/mm/slab.c b/mm/slab.c
> index 046607f..1496962 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -111,6 +111,7 @@
>  #include	<linux/rtmutex.h>
>  #include	<linux/reciprocal_div.h>
>  #include	<linux/debugobjects.h>
> +#include	<linux/kmemtrace.h>
>  
>  #include	<asm/cacheflush.h>
>  #include	<asm/tlbflush.h>
> @@ -567,6 +568,14 @@ static void **dbg_userword(struct kmem_cache *cachep, void *objp)
>  
>  #endif
>  
> +#ifdef CONFIG_KMEMTRACE
> +size_t slab_buffer_size(struct kmem_cache *cachep)
> +{
> +	return cachep->buffer_size;
> +}
> +EXPORT_SYMBOL(slab_buffer_size);
> +#endif
> +
>  /*
>   * Do not go above this order unless 0 objects fit into the slab.
>   */
> @@ -3621,10 +3630,23 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp)
>   */
>  void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
>  {
> -	return __cache_alloc(cachep, flags, __builtin_return_address(0));
> +	void *ret = __cache_alloc(cachep, flags, __builtin_return_address(0));
> +
> +	kmemtrace_mark_alloc(KMEMTRACE_TYPE_CACHE, _RET_IP_, ret,
> +			     obj_size(cachep), cachep->buffer_size, flags);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL(kmem_cache_alloc);
>  
> +#ifdef CONFIG_KMEMTRACE
> +void *kmem_cache_alloc_notrace(struct kmem_cache *cachep, gfp_t flags)
> +{
> +	return __cache_alloc(cachep, flags, __builtin_return_address(0));
> +}
> +EXPORT_SYMBOL(kmem_cache_alloc_notrace);
> +#endif
> +
>  /**
>   * kmem_ptr_validate - check if an untrusted pointer might be a slab entry.
>   * @cachep: the cache we're checking against
> @@ -3669,23 +3691,47 @@ out:
>  #ifdef CONFIG_NUMA
>  void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
>  {
> -	return __cache_alloc_node(cachep, flags, nodeid,
> -			__builtin_return_address(0));
> +	void *ret = __cache_alloc_node(cachep, flags, nodeid,
> +				       __builtin_return_address(0));
> +
> +	kmemtrace_mark_alloc_node(KMEMTRACE_TYPE_CACHE, _RET_IP_, ret,
> +				  obj_size(cachep), cachep->buffer_size,
> +				  flags, nodeid);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL(kmem_cache_alloc_node);
>  
> +#ifdef CONFIG_KMEMTRACE
> +void *kmem_cache_alloc_node_notrace(struct kmem_cache *cachep,
> +				    gfp_t flags,
> +				    int nodeid)
> +{
> +	return __cache_alloc_node(cachep, flags, nodeid,
> +				  __builtin_return_address(0));
> +}
> +EXPORT_SYMBOL(kmem_cache_alloc_node_notrace);
> +#endif
> +
>  static __always_inline void *
>  __do_kmalloc_node(size_t size, gfp_t flags, int node, void *caller)
>  {
>  	struct kmem_cache *cachep;
> +	void *ret;
>  
>  	cachep = kmem_find_general_cachep(size, flags);
>  	if (unlikely(ZERO_OR_NULL_PTR(cachep)))
>  		return cachep;
> -	return kmem_cache_alloc_node(cachep, flags, node);
> +	ret = kmem_cache_alloc_node_notrace(cachep, flags, node);
> +
> +	kmemtrace_mark_alloc_node(KMEMTRACE_TYPE_KMALLOC,
> +				  (unsigned long) caller, ret,
> +				  size, cachep->buffer_size, flags, node);
> +
> +	return ret;
>  }
>  
> -#ifdef CONFIG_DEBUG_SLAB
> +#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_KMEMTRACE)
>  void *__kmalloc_node(size_t size, gfp_t flags, int node)
>  {
>  	return __do_kmalloc_node(size, flags, node,
> @@ -3718,6 +3764,7 @@ static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
>  					  void *caller)
>  {
>  	struct kmem_cache *cachep;
> +	void *ret;
>  
>  	/* If you want to save a few bytes .text space: replace
>  	 * __ with kmem_.
> @@ -3727,11 +3774,17 @@ static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
>  	cachep = __find_general_cachep(size, flags);
>  	if (unlikely(ZERO_OR_NULL_PTR(cachep)))
>  		return cachep;
> -	return __cache_alloc(cachep, flags, caller);
> +	ret = __cache_alloc(cachep, flags, caller);
> +
> +	kmemtrace_mark_alloc(KMEMTRACE_TYPE_KMALLOC,
> +			     (unsigned long) caller, ret,
> +			     size, cachep->buffer_size, flags);
> +
> +	return ret;
>  }
>  
> 
> -#ifdef CONFIG_DEBUG_SLAB
> +#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_KMEMTRACE)
>  void *__kmalloc(size_t size, gfp_t flags)
>  {
>  	return __do_kmalloc(size, flags, __builtin_return_address(0));
> @@ -3770,6 +3823,8 @@ void kmem_cache_free(struct kmem_cache *cachep, void *objp)
>  		debug_check_no_obj_freed(objp, obj_size(cachep));
>  	__cache_free(cachep, objp);
>  	local_irq_restore(flags);
> +
> +	kmemtrace_mark_free(KMEMTRACE_TYPE_CACHE, _RET_IP_, objp);
>  }
>  EXPORT_SYMBOL(kmem_cache_free);
>  
> @@ -3796,6 +3851,8 @@ void kfree(const void *objp)
>  	debug_check_no_obj_freed(objp, obj_size(c));
>  	__cache_free(c, (void *)objp);
>  	local_irq_restore(flags);
> +
> +	kmemtrace_mark_free(KMEMTRACE_TYPE_KMALLOC, _RET_IP_, objp);
>  }
>  EXPORT_SYMBOL(kfree);
>  

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