On Fri, Jun 28, 2019 at 11:35:45AM +0300, Antony Pavlov wrote:
> On Wed, 26 Jun 2019 08:53:54 +0200
> Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote:
>
> > Hi Antony,
> >
> > On Fri, Jun 21, 2019 at 08:15:07AM +0300, Antony Pavlov wrote:
> > > flush_cache_all() uses 'struct cpuinfo_mips current_cpu_data' data fields.
> > > These data fields are initialized in r4k_cache_init().
> > >
> > > However in the current implementation the r4k_cache_init() function
> > > is called __AFTER__ relocate_code().
> > >
> > > Signed-off-by: Antony Pavlov <antonynpavlov@xxxxxxxxx>
> > > ---
> > > arch/mips/lib/reloc.c | 12 ++++++++++++
> > > 1 file changed, 12 insertions(+)
> > >
> > > diff --git a/arch/mips/lib/reloc.c b/arch/mips/lib/reloc.c
> > > index 14ba6167dd..6f1cd6d82f 100644
> > > --- a/arch/mips/lib/reloc.c
> > > +++ b/arch/mips/lib/reloc.c
> > > @@ -37,6 +37,7 @@
> > > #include <asm/mipsregs.h>
> > > #include <asm/relocs.h>
> > > #include <asm/sections.h>
> > > +#include <asm/cpu-features.h>
> > > #include <linux/sizes.h>
> > > #include <asm-generic/memory_layout.h>
> > >
> > > @@ -157,6 +158,17 @@ void relocate_code(void *fdt, u32 fdt_size, u32 ram_size)
> > > apply_reloc(type, (void *)addr, off);
> > > }
> > >
> > > + /* clear the BSS first */
> > > + memset(__bss_start, 0x00, bss_len);
> > > +
> > > + cpu_probe();
> > > +
> > > + if (cpu_has_4k_cache) {
> > > + extern void r4k_cache_init(void);
> > > +
> > > + r4k_cache_init();
> > > + }
> > > +
> > > /* Ensure the icache is coherent */
> > > flush_cache_all();
> >
> > Can we initialize one field in current_cpu_data to something nonzero so
> > that it goes out of the bss?
>
> Or clear only current_cpu_data and keep it in bss?
That would at least make it clear why this is done.
That's important because otherwise some day somebody sends a patch
"mips: remove duplicate clearing of bss" and I might apply it because
it looks correct ;)
There might be one problem with putting current_cpu_data into bss. I
don't know much about MIPS booting, but in case the initial image is
located in some potentially small SRAM then putting current_cpu_data
into bss means that the SRAM has to be big enough for initial image and
bss.
>
> > Another way would be to pass cpu_probe() a pointer to a struct
> > cpuinfo_mips allocated on the stack and then pass it to
> > flush_cache_all().
> >
> > Clearing the bss twice doesn't look very nice.
>
> It's two diffrent bss segments: one before relocation and one after relocation.
Yes, I know, otherwise you could just drop the second bss clearing.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
_______________________________________________
barebox mailing list
barebox@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/barebox
