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mtd: lpddr: fix excessive stack usage with clang 

[ Upstream commit 3e1b6469f8 ]

Building lpddr2_nvm with clang can result in a giant stack usage
in one function:

drivers/mtd/lpddr/lpddr2_nvm.c:399:12: error: stack frame size of 1144 bytes in function 'lpddr2_nvm_probe' [-Werror,-Wframe-larger-than=]

The problem is that clang decides to build a copy of the mtd_info
structure on the stack and then do a memcpy() into the actual version. It
shouldn't really do it that way, but it's not strictly a bug either.

As a workaround, use a static const version of the structure to assign
most of the members upfront and then only set the few members that
require runtime knowledge at probe time.

Fixes: 96ba9dd657 ("mtd: lpddr: add driver for LPDDR2-NVM PCM memories")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200505140136.263461-1-arnd@arndb.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Arnd Bergmann 2020-05-05 16:01:16 +02:00 committed by Greg Kroah-Hartman
parent 1564884a41
commit 4a5aaa1747
1 changed files with 19 additions and 16 deletions
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35
drivers/mtd/lpddr/lpddr2_nvm.c
View File

@ -393,6 +393,17 @@ static int lpddr2_nvm_lock(struct mtd_info *mtd, loff_t start_add,
return lpddr2_nvm_do_block_op(mtd, start_add, len, LPDDR2_NVM_LOCK);
}
static const struct mtd_info lpddr2_nvm_mtd_info = {
.type = MTD_RAM,
.writesize = 1,
.flags = (MTD_CAP_NVRAM | MTD_POWERUP_LOCK),
._read = lpddr2_nvm_read,
._write = lpddr2_nvm_write,
._erase = lpddr2_nvm_erase,
._unlock = lpddr2_nvm_unlock,
._lock = lpddr2_nvm_lock,
};
/*
* lpddr2_nvm driver probe method
*/
@ -433,6 +444,7 @@ static int lpddr2_nvm_probe(struct platform_device *pdev)
.pfow_base = OW_BASE_ADDRESS,
.fldrv_priv = pcm_data,
};
if (IS_ERR(map->virt))
return PTR_ERR(map->virt);
@ -444,22 +456,13 @@ static int lpddr2_nvm_probe(struct platform_device *pdev)
return PTR_ERR(pcm_data->ctl_regs);
/* Populate mtd_info data structure */
*mtd = (struct mtd_info) {
.dev = { .parent = &pdev->dev },
.name = pdev->dev.init_name,
.type = MTD_RAM,
.priv = map,
.size = resource_size(add_range),
.erasesize = ERASE_BLOCKSIZE * pcm_data->bus_width,
.writesize = 1,
.writebufsize = WRITE_BUFFSIZE * pcm_data->bus_width,
.flags = (MTD_CAP_NVRAM | MTD_POWERUP_LOCK),
._read = lpddr2_nvm_read,
._write = lpddr2_nvm_write,
._erase = lpddr2_nvm_erase,
._unlock = lpddr2_nvm_unlock,
._lock = lpddr2_nvm_lock,
};
*mtd = lpddr2_nvm_mtd_info;
mtd->dev.parent = &pdev->dev;
mtd->name = pdev->dev.init_name;
mtd->priv = map;
mtd->size = resource_size(add_range);
mtd->erasesize = ERASE_BLOCKSIZE * pcm_data->bus_width;
mtd->writebufsize = WRITE_BUFFSIZE * pcm_data->bus_width;
/* Verify the presence of the device looking for PFOW string */
if (!lpddr2_nvm_pfow_present(map)) {