/*
 * helpers for managing a buffer for many packets
 *
 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
 * Licensed under the terms of the GNU General Public License, version 2.
 */

#include <linux/firewire.h>
#include <linux/export.h>
#include <linux/slab.h>
#include "packets-buffer.h"

/**
 * iso_packets_buffer_init - allocates the memory for packets
 * @b: the buffer structure to initialize
 * @unit: the device at the other end of the stream
 * @count: the number of packets
 * @packet_size: the (maximum) size of a packet, in bytes
 * @direction: %DMA_TO_DEVICE or %DMA_FROM_DEVICE
 */
int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
			    unsigned int count, unsigned int packet_size,
			    enum dma_data_direction direction)
{
	unsigned int packets_per_page, pages;
	unsigned int i, page_index, offset_in_page;
	void *p;
	int err;

	b->packets = kmalloc(count * sizeof(*b->packets), GFP_KERNEL);
	if (!b->packets) {
		err = -ENOMEM;
		goto error;
	}

	packet_size = L1_CACHE_ALIGN(packet_size);
	packets_per_page = PAGE_SIZE / packet_size;
	if (WARN_ON(!packets_per_page)) {
		err = -EINVAL;
		goto error;
	}
	pages = DIV_ROUND_UP(count, packets_per_page);

	err = fw_iso_buffer_init(&b->iso_buffer, fw_parent_device(unit)->card,
				 pages, direction);
	if (err < 0)
		goto err_packets;

	for (i = 0; i < count; ++i) {
		page_index = i / packets_per_page;
		p = page_address(b->iso_buffer.pages[page_index]);
		offset_in_page = (i % packets_per_page) * packet_size;
		b->packets[i].buffer = p + offset_in_page;
		b->packets[i].offset = page_index * PAGE_SIZE + offset_in_page;
	}

	return 0;

err_packets:
	kfree(b->packets);
error:
	return err;
}
EXPORT_SYMBOL(iso_packets_buffer_init);

/**
 * iso_packets_buffer_destroy - frees packet buffer resources
 * @b: the buffer structure to free
 * @unit: the device at the other end of the stream
 */
void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
				struct fw_unit *unit)
{
	fw_iso_buffer_destroy(&b->iso_buffer, fw_parent_device(unit)->card);
	kfree(b->packets);
}
EXPORT_SYMBOL(iso_packets_buffer_destroy);
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ss='logsubject'><a href='/cgit.cgi/linux/net-next.git/commit/include/asm-generic?id=71810db27c1c853b335675bee335d893bc3d324b'>modversions: treat symbol CRCs as 32 bit quantities</a></td><td>Ard Biesheuvel</td><td>1</td><td><span class='deletions'>-5</span>/<span class='insertions'>+6</span></td></tr>
<tr class='nohover-highlight'><td/><td colspan='5' class='logmsg'>
The modversion symbol CRCs are emitted as ELF symbols, which allows us
to easily populate the kcrctab sections by relying on the linker to
associate each kcrctab slot with the correct value.

This has a couple of downsides:

 - Given that the CRCs are treated as memory addresses, we waste 4 bytes
   for each CRC on 64 bit architectures,

 - On architectures that support runtime relocation, a R_&lt;arch&gt;_RELATIVE
   relocation entry is emitted for each CRC value, which identifies it
   as a quantity that requires fixing up based on the actual runtime
   load offset of the kernel. This results in corrupted CRCs unless we
   explicitly undo the fixup (and this is currently being handled in the
   core module code)

 - Such runtime relocation entries take up 24 bytes of __init space
   each, resulting in a x8 overhead in [uncompressed] kernel size for
   CRCs.

Switching to explicit 32 bit values on 64 bit architectures fixes most
of these issues, given that 32 bit values are not treated as quantities
that require fixing up based on the actual runtime load offset.  Note
that on some ELF64 architectures [such as PPC64], these 32-bit values
are still emitted as [absolute] runtime relocatable quantities, even if
the value resolves to a build time constant.  Since relative relocations
are always resolved at build time, this patch enables MODULE_REL_CRCS on
powerpc when CONFIG_RELOCATABLE=y, which turns the absolute CRC
references into relative references into .rodata where the actual CRC
value is stored.

So redefine all CRC fields and variables as u32, and redefine the
__CRC_SYMBOL() macro for 64 bit builds to emit the CRC reference using
inline assembler (which is necessary since 64-bit C code cannot use
32-bit types to hold memory addresses, even if they are ultimately
resolved using values that do not exceed 0xffffffff).  To avoid
potential problems with legacy 32-bit architectures using legacy
toolchains, the equivalent C definition of the kcrctab entry is retained
for 32-bit architectures.

Note that this mostly reverts commit d4703aefdbc8 ("module: handle ppc64
relocating kcrctabs when CONFIG_RELOCATABLE=y")

Acked-by: Rusty Russell &lt;rusty@rustcorp.com.au&gt;
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;


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