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32b064108a
The new code allows to replace the existing one buffer at a time
shared memory facility with a malloc/free implementation. A new
configuration option is being provided (CONFIG_MALLOC).
The names of functions allocating and freeing memory are not being
changed to allow to switch between the two implementations seamlessly.
A double linked list of buffers is used to keep track of free and
allocated memory. During initialization the entire free memory block
is considered a single free buffer. No allocations/frees are allowed
from within interrupts. The control structures are protected by a
semaphore, so allocate and free invocation could be blocking.
A test is added which randomly allocates and frees memory, continuing
until all branches in the allocate and free functions are taken.
BUG=chrome-os-partner:
TEST=make buildall -j succeeds, which includes testing the new
malloc/free implementation.
Change-Id: I5e71c0190c6c247ec73bb459f66a6d7a06e3d248
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/420466
Reviewed-by: Randall Spangler <rspangler@chromium.org>
80 lines
2.4 KiB
C
80 lines
2.4 KiB
C
/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/*
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* Shared memory interface for Chrome EC.
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*
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* This is intended to supply a relatively large block of memory for use by a
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* task for a relatively short amount of time. For example, verified boot may
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* need a buffer to hold signature data during a verification operation. It is
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* NOT intended for allocating long-term buffers; those should in general be
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* static variables allocated at compile-time. It is NOT a full-featured
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* replacement for malloc() / free().
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*/
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#ifndef __CROS_EC_SHARED_MEM_H
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#define __CROS_EC_SHARED_MEM_H
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#include "common.h"
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#include <stddef.h>
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/**
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* Returns the maximum amount of shared memory which can be acquired, in
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* bytes.
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*/
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int shared_mem_size(void);
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/*
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* Acquires a shared memory area of the requested size in bytes.
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*
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* Doing a sysjump between images will corrupt and/or erase shared memory as
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* jump tags are added and .bss is reinitialized. Due to the way jump tags are
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* added to the end of RAM, shared memory must not be allocated, accessed, or
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* freed after the start of a sysjump (for example, in HOOK_SYSJUMP).
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*
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* @param size Number of bytes requested
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* @param dest_ptr If successful, set on return to the start of the
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* granted memory buffer.
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*
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* @return EC_SUCCESS if successful, EC_ERROR_BUSY if buffer in use, or
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* other non-zero error code.
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*/
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int shared_mem_acquire(int size, char **dest_ptr);
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/**
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* Releases a shared memory area previously allocated via shared_mem_acquire().
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*/
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void shared_mem_release(void *ptr);
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/*
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* This structure is allocated at the base of the free memory chunk and every
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* allocated buffer.
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*/
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struct shm_buffer {
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struct shm_buffer *next_buffer;
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struct shm_buffer *prev_buffer;
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size_t buffer_size;
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};
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#ifdef TEST_BUILD
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/*
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* When in test mode, all possible paths in the allocation/free functions set
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* unique bits in an integer bitmap.
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*
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* The test function generates random allocation and free requests and
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* monitors the bitmap until all bits have been set, which indicates that all
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* possible paths have been executed.
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*/
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#define MAX_MASK_BIT 24
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#define ALL_PATHS_MASK ((1 << (MAX_MASK_BIT + 1)) - 1)
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void set_map_bit(uint32_t mask);
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extern struct shm_buffer *free_buf_chain;
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extern struct shm_buffer *allocced_buf_chain;
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#endif
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#endif /* __CROS_EC_SHARED_MEM_H */
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