Nathan Chancellor <natechancel...@gmail.com> wrote on Tue, 5 May 2020
19:38:28 -0700:
> On Tue, May 05, 2020 at 04:01:16PM +0200, Arnd Bergmann wrote:
> > 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: 96ba9dd65788 ("mtd: lpddr: add driver for LPDDR2-NVM PCM memories")
> > Signed-off-by: Arnd Bergmann <a...@arndb.de>
>
> Reviewed-by: Nathan Chancellor <natechancel...@gmail.com>
Acked-by: Miquel Raynal <miquel.ray...@bootlin.com>
>
> > ---
> > drivers/mtd/lpddr/lpddr2_nvm.c | 35 ++++++++++++++++++----------------
> > 1 file changed, 19 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/mtd/lpddr/lpddr2_nvm.c b/drivers/mtd/lpddr/lpddr2_nvm.c
> > index 0f1547f09d08..72f5c7b30079 100644
> > --- a/drivers/mtd/lpddr/lpddr2_nvm.c
> > +++ b/drivers/mtd/lpddr/lpddr2_nvm.c
> > @@ -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)) {
> > --
> > 2.26.0
> >
