Hi
On Mon, Jul 31, 2023 at 10:10 AM Heinrich Schuchardt <
heinrich.schucha...@canonical.com> wrote:
>
>
>
> On 7/31/23 09:00, Michael Nazzareno Trimarchi wrote:
> > Hi
> >
> > On Sun, Jul 30, 2023 at 3:03 PM Heinrich Schuchardt
> > <heinrich.schucha...@canonical.com> wrote:
> >>
> >> Multiplication of u32 factors has an u32 result even if an overflow
occurs.
> >> An overflow may occur in
> >>
> >> u64 data_off = page * mtd->writesize;
> >>
> >> The size of the flash device may exceed 4 GiB.
> >>
> >
> > Instead of force variables to u64 just cast where expansion is needed
before
> > multiple. Why we should thinking to have u64 number of nand pages?
>
> Does anything stop MTD devices from reaching 2^32 pages?
>
Pages is integer right now in the code. What is the problem just to fix
what you are claim
Michael
> The driver layer uses loff_t for 'from'. I can't see any limitation there.
>
> Best regards
>
> Heinrich
>
> >
> > Michael
> >
> >> Play it safe and use u64 consistently.
> >>
> >> Signed-off-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com>
> >> ---
> >> cmd/mtd.c | 17 +++++++----------
> >> 1 file changed, 7 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/cmd/mtd.c b/cmd/mtd.c
> >> index eb6e2d6892..fb6e2bb047 100644
> >> --- a/cmd/mtd.c
> >> +++ b/cmd/mtd.c
> >> @@ -33,11 +33,9 @@ static struct mtd_info *get_mtd_by_name(const char
*name)
> >> return mtd;
> >> }
> >>
> >> -static uint mtd_len_to_pages(struct mtd_info *mtd, u64 len)
> >> +static u64 mtd_len_to_pages(struct mtd_info *mtd, u64 len)
> >> {
> >> - do_div(len, mtd->writesize);
> >> -
> >> - return len;
> >> + return lldiv(len, mtd->writesize);
> >> }
> >>
> >> static bool mtd_is_aligned_with_min_io_size(struct mtd_info *mtd,
u64 size)
> >> @@ -72,8 +70,7 @@ static void mtd_dump_device_buf(struct mtd_info
*mtd, u64 start_off,
> >> {
> >> bool has_pages = mtd->type == MTD_NANDFLASH ||
> >> mtd->type == MTD_MLCNANDFLASH;
> >> - int npages = mtd_len_to_pages(mtd, len);
> >> - uint page;
> >> + u64 page, npages = mtd_len_to_pages(mtd, len);
> >>
> >> if (has_pages) {
> >> for (page = 0; page < npages; page++) {
> >> @@ -251,12 +248,12 @@ static int do_mtd_io(struct cmd_tbl *cmdtp, int
flag, int argc,
> >> char *const argv[])
> >> {
> >> bool dump, read, raw, woob, write_empty_pages, has_pages =
false;
> >> - u64 start_off, off, len, remaining, default_len;
> >> + u64 start_off, off, len, oob_len, remaining, default_len;
> >> struct mtd_oob_ops io_op = {};
> >> - uint user_addr = 0, npages;
> >> + uint user_addr = 0;
> >> + u64 npages;
> >> const char *cmd = argv[0];
> >> struct mtd_info *mtd;
> >> - u32 oob_len;
> >> u8 *buf;
> >> int ret;
> >>
> >> @@ -322,7 +319,7 @@ static int do_mtd_io(struct cmd_tbl *cmdtp, int
flag, int argc,
> >> }
> >>
> >> if (has_pages)
> >> - printf("%s %lld byte(s) (%d page(s)) at offset
0x%08llx%s%s%s\n",
> >> + printf("%s %lld byte(s) (%lld page(s)) at offset
0x%08llx%s%s%s\n",
> >> read ? "Reading" : "Writing", len, npages,
start_off,
> >> raw ? " [raw]" : "", woob ? " [oob]" : "",
> >> !read && write_empty_pages ? " [dontskipff]" :
"");
> >> --
> >> 2.40.1
> >>
