[U-Boot] [PATCH] lib: tiny-printf: Add "%ll" modifier support

[Ley Foon Tan <lftan.linux@gmail.com>]

On Thu, Mar 21, 2019 at 7:22 PM Tom Rini <trini@konsulko.com> wrote:
>
> On Fri, Mar 22, 2019 at 01:12:14AM +0800, Ley Foon Tan wrote:
>
> > Add "%ll" modifier support for tiny printf.
> >
> > - Tested on ARM32 and ARM64 systems.
> > - Tested "%lld", "%llu", "%llx" and "%p" format with
> >   minimum and maximum ranges. Compared tiny printf
> >   output with full printf.
> >
> > Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
> > ---
> >  lib/tiny-printf.c | 42 +++++++++++++++++++++++++++++-------------
> >  1 file changed, 29 insertions(+), 13 deletions(-)
>
> What's the use case for this, how much does it grow the size, and can
> the code in question be changed to use a different format modifier or be
> debug() instead?  Tiny printf isn't intended to cover all formats but
> rather still allow some amount of printf on constrained systems.
> Thanks!
>
> --
> Tom
This is to support printf %lld, %llu and %llx and 64-bit %p when
CONFIG_USE_TINY_PRINTF=y is enabled.
In 64-bit system, phys_size_t and phys_addr_t are unsigned long long.
Printf these variables will see rubbish in existing tiny printf.

Example %ll printf;
printf("9223372036854775807 ==> %lld \n",  (long long)9223372036854775807);
printf("0xffffffffffffffff ==> 0x%llx \n", (unsigned long
long)0xffffffffffffffff);

There are few issues I've noticed with original tiny printf:
- Some common codes use %ll format
- %p in tiny printf only support 32-bit, it can't support 64-bit address.

If DEBUG is defined and with tiny printf. You can see all rubbish x
for %llx printf. The most serious issue is it cause system hang at
line below (printf from common code).
addr=x level=0
idx=x PTE  at level 16384: x
Creating table for virt 0xx
Setting 4000 to addr=5000
addr=x level=0
idx=x PTE  at level 16384: x
idx=x PTE  at level 20480: x
Checking if pte fits for virt=x size=x blocksize=x
Setting PTE 5000 to block virt=x
addr=x level=1073741824
idx=x PTE  at level 16384: x
addr=x level=1073741824
idx=x PTE  at level 16384: x
idx=x PTE 1 at level 20488: x
Checking if pte fits for virt=x size=x blocksize=x
Setting PTE 5008 to block virt=x
addr=x level=

Example output after apply this patch:
idx=0 PTE 8000 at level 0: 9003
idx=3 PTE 9018 at level 1: a003
Checking if pte fits for virt=c0600000 size=1fa00000 blocksize=40000000
addr=c0600000 level=2
idx=0 PTE 8000 at level 0: 9003
idx=3 PTE 9018 at level 1: a003


ARM64:
----------
It increase 200 bytes.

Before:
   text       data        bss        dec        hex    filename
  69618       5296        232      75146      1258a    spl/u-boot-spl

After:
   text       data        bss        dec        hex    filename
  69818       5296        232      75346      12652    spl/u-boot-spl


ARM32:
----------
It increase 644 bytes.

Before:
   text       data        bss        dec        hex    filename
  31825       2968        132      34925       886d    spl/u-boot-spl

After:
   text    data     bss     dec     hex filename
  32469    2968     132   35569    8af1 spl/u-boot-spl

Regards
Ley Foon