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buflib: refactor CRC checks as paranoia

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Move CRC checking and updating behind a paranoia bit, like the
other checks, so it can be enabled and disabled.

Change-Id: Icff66c842cbd5af2d99aa91e6c40447a64e6d4b2
This commit is contained in:
Aidan MacDonald 2022-03-30 18:15:49 +01:00
parent f82f3044a7
commit dcc4e54b77
1 changed files with 54 additions and 24 deletions
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78
firmware/buflib.c
View file

@ -101,6 +101,7 @@
#define PARANOIA_CHECK_LENGTH (1 << 0)
#define PARANOIA_CHECK_HANDLE (1 << 1)
#define PARANOIA_CHECK_BLOCK_HANDLE (1 << 2)
#define PARANOIA_CHECK_CRC (1 << 3)
/* Bitmask of enabled paranoia checks */
#define BUFLIB_PARANOIA 0
@ -166,6 +167,16 @@ static void check_handle(struct buflib_context *ctx,
static void check_block_handle(struct buflib_context *ctx,
union buflib_data *block);
/* Update the block's CRC checksum if CRCs are enabled. */
static void update_block_crc(struct buflib_context *ctx,
union buflib_data *block,
union buflib_data *block_end);
/* Check the block's CRC if CRCs are enabled. */
static void check_block_crc(struct buflib_context *ctx,
union buflib_data *block,
union buflib_data *block_end);
/* Initialize buffer manager */
void
buflib_init(struct buflib_context *ctx, void *buf, size_t size)
@ -334,14 +345,6 @@ static inline bool handle_table_shrink(struct buflib_context *ctx)
return handle != old_last;
}
static uint32_t calc_block_crc(union buflib_data *block,
union buflib_data *block_end)
{
union buflib_data *crc_slot = &block_end[-bidx_CRC];
const size_t size = (crc_slot - block) * sizeof(*block);
return crc_32(block, size, 0xffffffff);
}
/* If shift is non-zero, it represents the number of places to move
* blocks in memory. Calculate the new address for this block,
* update its entry in the handle table, and then move its contents.
@ -358,11 +361,7 @@ move_block(struct buflib_context* ctx, union buflib_data* block, int shift)
check_block_handle(ctx, block);
union buflib_data *h_entry = block[fidx_HANDLE].handle;
union buflib_data *block_end = h_entry_to_block_end(ctx, h_entry);
uint32_t crc = calc_block_crc(block, block_end);
if (crc != block_end[-bidx_CRC].crc)
buflib_panic(ctx, "buflib metadata corrupted, crc: 0x%08x, expected: 0x%08x",
(unsigned int)crc, (unsigned int)block_end[-bidx_CRC].crc);
check_block_crc(ctx, block, block_end);
if (!IS_MOVABLE(block))
return false;
@ -722,13 +721,12 @@ buffer_alloc:
size_t bsize = BUFLIB_NUM_FIELDS + name_len/sizeof(union buflib_data);
union buflib_data *block_end = block + bsize;
block_end[-bidx_BSIZE].val = bsize;
block_end[-bidx_CRC].crc = calc_block_crc(block, block_end);
update_block_crc(ctx, block, block_end);
handle->alloc = (char*)&block_end[-bidx_USER];
BDEBUGF("buflib_alloc_ex: size=%d handle=%p clb=%p crc=0x%0x name=\"%s\"\n",
(unsigned int)size, (void *)handle, (void *)ops,
(unsigned int)block_end[-bidx_CRC].crc, name ? name : "");
BDEBUGF("buflib_alloc_ex: size=%d handle=%p clb=%p name=\"%s\"\n",
(unsigned int)size, (void *)handle, (void *)ops, name ? name : "");
block += size;
/* alloc_end must be kept current if we're taking the last block. */
@ -1000,7 +998,7 @@ buflib_shrink(struct buflib_context* ctx, int handle, void* new_start, size_t ne
/* update crc of the metadata */
union buflib_data *new_h_entry = new_block[fidx_HANDLE].handle;
union buflib_data *new_block_end = h_entry_to_block_end(ctx, new_h_entry);
new_block_end[-bidx_CRC].crc = calc_block_crc(new_block, new_block_end);
update_block_crc(ctx, new_block, new_block_end);
/* Now deal with size changes that create free blocks after the allocation */
if (old_next_block != new_next_block)
@ -1055,12 +1053,7 @@ void buflib_check_valid(struct buflib_context *ctx)
check_block_handle(ctx, block);
union buflib_data *h_entry = block[fidx_HANDLE].handle;
union buflib_data *block_end = h_entry_to_block_end(ctx, h_entry);
uint32_t crc = calc_block_crc(block, block_end);
if (crc != block_end[-bidx_CRC].crc)
{
buflib_panic(ctx, "crc mismatch: 0x%08x, expected: 0x%08x",
(unsigned int)crc, (unsigned int)block_end[-bidx_CRC].crc);
}
check_block_crc(ctx, block, block_end);
}
}
#endif
@ -1217,3 +1210,40 @@ static void check_block_handle(struct buflib_context *ctx,
}
}
}
static uint32_t calc_block_crc(union buflib_data *block,
union buflib_data *block_end)
{
union buflib_data *crc_slot = &block_end[-bidx_CRC];
const size_t size = (crc_slot - block) * sizeof(*block);
return crc_32(block, size, 0xffffffff);
}
static void update_block_crc(struct buflib_context *ctx,
union buflib_data *block,
union buflib_data *block_end)
{
(void)ctx;
if (BUFLIB_PARANOIA & PARANOIA_CHECK_CRC)
{
block_end[-bidx_CRC].crc = calc_block_crc(block, block_end);
}
}
static void check_block_crc(struct buflib_context *ctx,
union buflib_data *block,
union buflib_data *block_end)
{
if (BUFLIB_PARANOIA & PARANOIA_CHECK_CRC)
{
uint32_t crc = calc_block_crc(block, block_end);
if (block_end[-bidx_CRC].crc != crc)
{
buflib_panic(ctx, "buflib crc mismatch [%p]=%08lx, got %08lx",
&block_end[-bidx_CRC],
(unsigned long)block_end[-bidx_CRC].crc,
(unsigned long)crc);
}
}
}