Re: [PATCH v3 3/5] RISC-V: Improve init_resources

[Geert Uytterhoeven]

Hi Nick,

On Tue, Apr 6, 2021 at 10:11 AM Nick Kossifidis <mick@xxxxxxxxxxxx> wrote:
> Hello Geert,
> Στις 2021-04-06 10:19, Geert Uytterhoeven έγραψε:
> > On Mon, Apr 5, 2021 at 10:57 AM Nick Kossifidis <mick@xxxxxxxxxxxx>
> > wrote:
> >> * Kernel region is always present and we know where it is, no
> >> need to look for it inside the loop, just ignore it like the
> >> rest of the reserved regions within system's memory.
> >>
> >> * Don't call memblock_free inside the loop, if called it'll split
> >> the region of pre-allocated resources in two parts, messing things
> >> up, just re-use the previous pre-allocated resource and free any
> >> unused resources after both loops finish.
> >>
> >> * memblock_alloc may add a region when called, so increase the
> >> number of pre-allocated regions by one to be on the safe side
> >> (reported and patched by Geert Uytterhoeven)
> >>
> >> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> >
> > Where does this SoB come from?
> >
> >> Signed-off-by: Nick Kossifidis <mick@xxxxxxxxxxxx>
> >
> >> --- a/arch/riscv/kernel/setup.c
> >> +++ b/arch/riscv/kernel/setup.c
> >
> >> @@ -129,53 +139,42 @@ static void __init init_resources(void)
> >>         struct resource *res = NULL;
> >>         struct resource *mem_res = NULL;
> >>         size_t mem_res_sz = 0;
> >> -       int ret = 0, i = 0;
> >> -
> >> -       code_res.start = __pa_symbol(_text);
> >> -       code_res.end = __pa_symbol(_etext) - 1;
> >> -       code_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> -
> >> -       rodata_res.start = __pa_symbol(__start_rodata);
> >> -       rodata_res.end = __pa_symbol(__end_rodata) - 1;
> >> -       rodata_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> -
> >> -       data_res.start = __pa_symbol(_data);
> >> -       data_res.end = __pa_symbol(_edata) - 1;
> >> -       data_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> +       int num_resources = 0, res_idx = 0;
> >> +       int ret = 0;
> >>
> >> -       bss_res.start = __pa_symbol(__bss_start);
> >> -       bss_res.end = __pa_symbol(__bss_stop) - 1;
> >> -       bss_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> >> +       /* + 1 as memblock_alloc() might increase
> >> memblock.reserved.cnt */
> >> +       num_resources = memblock.memory.cnt + memblock.reserved.cnt +
> >> 1;
> >> +       res_idx = num_resources - 1;
> >>
> >> -       mem_res_sz = (memblock.memory.cnt + memblock.reserved.cnt) *
> >> sizeof(*mem_res);
> >
> > Oh, you incorporated my commit ce989f1472ae350e ("RISC-V: Fix
> > out-of-bounds
> > accesses in init_resources()") (from v5.12-rc4) into your patch.
> > Why? This means your patch does not apply against upstream.
> >
>
> Sorry if this looks awkward, I'm under the impression that new features
> go on for-next instead of fixes and your patch hasn't been merged on
> for-next yet. I thought it would be cleaner to have one patch to merge
> for init_resources instead of two, and simpler for people to test the
> series. I can rebase this on top of fixes if that works better for you
> or Palmer.

Ideally the fixes branch is part of the next branch.  That also helps
to avoid other people having to fix conflicts when merging both.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds