mars/kernel/brick_mem.h

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// (c) 2011 Thomas Schoebel-Theuer / 1&1 Internet AG
#ifndef BRICK_MEM_H
#define BRICK_MEM_H
#include <linux/mm_types.h>
#define BRICK_DEBUG_MEM 4096
#ifndef CONFIG_MARS_DEBUG_MEM
#undef BRICK_DEBUG_MEM
#endif
#ifdef CONFIG_MARS_DEBUG_ORDER0
#define BRICK_DEBUG_ORDER0
#endif
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#define GFP_BRICK GFP_NOIO
//#define GFP_BRICK GFP_KERNEL // can lead to deadlocks!
extern long long brick_global_memavail;
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extern long long brick_global_memlimit;
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extern atomic64_t brick_global_block_used;
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/////////////////////////////////////////////////////////////////////////
// compiler tweaking
/* Some functions are known to return non-null pointer values,
* at least under some Kconfig conditions.
*
* In code like...
*
* void *ptr = myfunction();
* if (unlikely(!ptr)) {
* printk("ERROR: this should not happen\n");
* goto fail;
* }
*
* ... the dead code elimination of gcc will not remove the if clause
* because the function might return a NULL value, even if a human
* would know that myfunction() does not return a NULL value.
*
* Unfortunately, the __attribute__((nonnull)) can only be applied
* to input parameters, but not to the return value.
*
* More unfortunately, a small inline wrapper does not help,
* because it seems that together with the elimination of the wrapper,
* its nonnull attribute seems to be eliminated alltogether.
* I don't know whether this is a bug or a feature (or just a weakness).
*
* Following is a small hack which solves the problem at least for gcc 4.7.
*
* In order to be useful, the -fdelete-null-pointer-checks must be set.
* Since MARS is superuser-only anyway, enabling this for MARS should not
* be a security risk
* (c.f. upstream kernel commit a3ca86aea507904148870946d599e07a340b39bf)
*/
extern inline
void *__mark_ptr_nonnull(void *_ptr)
{
char *ptr = _ptr;
// fool gcc to believe that the pointer were dereferenced...
asm("" : : "X" (*ptr));
return ptr;
}
/* All the brick memory allocations are guaranteed to succeed when
* CONFIG_MARS_MEM_RETRY is set. In case of low memory, they will just
* retry (forever).
*
* Allow checking code to be written which works for both cases:
* CONFIG_MARS_MEM_RETRY is selected, or not.
*/
#ifdef CONFIG_MARS_MEM_RETRY
#define brick_mark_nonnull __mark_ptr_nonnull
#else
#define brick_mark_nonnull(p) (p)
#endif
/////////////////////////////////////////////////////////////////////////
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// small memory allocation (use this only for len < PAGE_SIZE)
#define brick_mem_alloc(_len_) \
({ \
void *_res_ = _brick_mem_alloc(_len_, __LINE__); \
brick_mark_nonnull(_res_); \
})
#define brick_zmem_alloc(_len_) \
({ \
void *_res_ = _brick_mem_alloc(_len_, __LINE__); \
_res_ = brick_mark_nonnull(_res_); \
if (_res_) { \
memset(_res_, 0, _len_); \
} \
_res_; \
})
#define brick_mem_free(_data_) \
do { \
if (_data_) { \
_brick_mem_free(_data_, __LINE__); \
} \
} while(0)
// don't use the following directly
extern void *_brick_mem_alloc(int len, int line) __attribute__((malloc)) __attribute__((alloc_size(1)));
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extern void _brick_mem_free(void *data, int line);
/////////////////////////////////////////////////////////////////////////
// string memory allocation
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#define BRICK_STRING_LEN 1024 /* default value when len == 0 */
#define brick_string_alloc(_len_) \
({ \
char *_res_ = _brick_string_alloc((_len_), __LINE__); \
(char*)brick_mark_nonnull(_res_); \
})
#define brick_strndup(_orig_,_len_) \
({ \
char *_res_ = _brick_string_alloc((_len_) + 1, __LINE__); \
_res_ = brick_mark_nonnull(_res_); \
if (_res_) { \
strncpy(_res_, (_orig_), (_len_) + 1); \
/* always null-terminate for safety */ \
_res_[_len_] = '\0'; \
} \
(char*)brick_mark_nonnull(_res_); \
})
#define brick_strdup(_orig_) \
({ \
int _len_ = strlen(_orig_); \
char *_res_ = _brick_string_alloc((_len_) + 1, __LINE__); \
_res_ = brick_mark_nonnull(_res_); \
if (_res_) { \
strncpy(_res_, (_orig_), (_len_) + 1); \
} \
(char*)brick_mark_nonnull(_res_); \
})
#define brick_string_free(_data_) \
do { \
if (_data_) { \
_brick_string_free(_data_, __LINE__); \
} \
} while(0)
// don't use the following directly
extern char *_brick_string_alloc(int len, int line) __attribute__((malloc));
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extern void _brick_string_free(const char *data, int line);
/////////////////////////////////////////////////////////////////////////
// block memory allocation (for aligned multiples of 512 resp PAGE_SIZE)
#define brick_block_alloc(_pos_,_len_) \
({ \
void *_res_ = _brick_block_alloc((_pos_), (_len_), __LINE__); \
brick_mark_nonnull(_res_); \
})
#define brick_block_free(_data_,_len_)\
do { \
if (_data_) { \
_brick_block_free((_data_), (_len_), __LINE__); \
} \
} while(0)
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extern struct page *brick_iomap(void *data, int *offset, int *len);
// don't use the following directly
extern void *_brick_block_alloc(loff_t pos, int len, int line) __attribute__((malloc)) __attribute__((alloc_size(2)));
extern void _brick_block_free(void *data, int len, int cline);
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/////////////////////////////////////////////////////////////////////////
// reservations / preallocation
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#define BRICK_MAX_ORDER 11
extern bool brick_allow_freelist;
struct mem_reservation {
int amount[BRICK_MAX_ORDER+1];
};
extern int brick_mem_reserve(struct mem_reservation *r);
extern void brick_mem_statistics(void);
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/////////////////////////////////////////////////////////////////////////
// init
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#ifdef CONFIG_MARS_HAVE_BIGMODULE
#undef __exit
#define __exit /*empty*/
#endif
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extern int init_brick_mem(void);
extern void exit_brick_mem(void);
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#endif