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Date:   Fri, 09 Oct 2020 14:23:43 -0700 (PDT)
Subject:     Re: [PATCH 2/2] riscv: Fixup static_obj() fail v2
In-Reply-To: <CAOnJCUKcs8quZdHDx6SZ0USbOifE1D_zeL7XaGqMr+-DuN1MwQ@mail.gmail.com>
CC:     guoren@kernel.org, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org, schwab@linux-m68k.org,
        aurelien@aurel32.net, guoren@linux.alibaba.com
From:   Palmer Dabbelt <palmerdabbelt@google.com>
To:     atishp@atishpatra.org
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On Fri, 09 Oct 2020 14:16:00 PDT (-0700), atishp@atishpatra.org wrote:
> On Thu, Oct 8, 2020 at 6:53 PM Guo Ren <guoren@kernel.org> wrote:
>>
>> On Thu, Oct 8, 2020 at 11:54 AM Palmer Dabbelt <palmerdabbelt@google.com> wrote:
>> >
>> > On Wed, 07 Oct 2020 08:08:33 PDT (-0700), guoren@kernel.org wrote:
>> > > From: Guo Ren <guoren@linux.alibaba.com>
>> > >
>> > > v1 is commit: 6184358da0004c8fd940afda6c0a0fa4027dc911 which has
>> > > been reverted.
>> > >
>> > > When enable LOCKDEP, static_obj() will cause error:
>> > >
>> > > [    0.067192] INFO: trying to register non-static key.
>> > > [    0.067325] the code is fine but needs lockdep annotation.
>> > > [    0.067449] turning off the locking correctness validator.
>> > > [    0.067718] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-rc7-dirty #44
>> > > [    0.067945] Call Trace:
>> > > [    0.068369] [<ffffffe00020323c>] walk_stackframe+0x0/0xa4
>> > > [    0.068506] [<ffffffe000203422>] show_stack+0x2a/0x34
>> > > [    0.068631] [<ffffffe000521e4e>] dump_stack+0x94/0xca
>> > > [    0.068757] [<ffffffe000255a4e>] register_lock_class+0x5b8/0x5bc
>> > > [    0.068969] [<ffffffe000255abe>] __lock_acquire+0x6c/0x1d5c
>> > > [    0.069101] [<ffffffe0002550fe>] lock_acquire+0xae/0x312
>> > > [    0.069228] [<ffffffe000989a8e>] _raw_spin_lock_irqsave+0x40/0x5a
>> > > [    0.069357] [<ffffffe000247c64>] complete+0x1e/0x50
>> > > [    0.069479] [<ffffffe000984c38>] rest_init+0x1b0/0x28a
>> > > [    0.069660] [<ffffffe0000016a2>] 0xffffffe0000016a2
>> > > [    0.069779] [<ffffffe000001b84>] 0xffffffe000001b84
>> > > [    0.069953] [<ffffffe000001092>] 0xffffffe000001092
>> > >
>> > > Because some __initdata static variables is before _stext:
>> > >
>> > > static int static_obj(const void *obj)
>> > > {
>> > >         unsigned long start = (unsigned long) &_stext,
>> > >                       end   = (unsigned long) &_end,
>> > >                       addr  = (unsigned long) obj;
>> > >
>> > >         /*
>> > >          * static variable?
>> > >          */
>> > >         if ((addr >= start) && (addr < end))
>> > >                 return 1;
>> > >
>> > >       if (arch_is_kernel_data(addr))
>> > >               return 1;
>> > >
>> > > We could implement arch_is_kernel_data to fixup it.
>> > >
>> > > Link: https://lore.kernel.org/linux-riscv/1593266228-61125-1-git-send-email-guoren@kernel.org/T/#t
>> > > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
>> > > Reported-by: Aurelien Jarno <aurelien@aurel32.net>
>> > > Cc: Palmer Dabbelt <palmerdabbelt@google.com>
>> > > Cc: Atish Patra <atishp@atishpatra.org>
>> > > Cc: Andreas Schwab <schwab@linux-m68k.org>
>> > > Cc: Aurelien Jarno <aurelien@aurel32.net>
>> > > ---
>> > >  arch/riscv/include/asm/sections.h | 20 ++++++++++++++++++++
>> > >  arch/riscv/kernel/setup.c         |  9 +++++++++
>> > >  2 files changed, 29 insertions(+)
>> > >  create mode 100644 arch/riscv/include/asm/sections.h
>> > >
>> > > diff --git a/arch/riscv/include/asm/sections.h b/arch/riscv/include/asm/sections.h
>> > > new file mode 100644
>> > > index 00000000..2317b9e
>> > > --- /dev/null
>> > > +++ b/arch/riscv/include/asm/sections.h
>> > > @@ -0,0 +1,20 @@
>> > > +/* SPDX-License-Identifier: GPL-2.0-only */
>> > > +
>> > > +#ifndef _ASM_RISCV_SECTIONS_H
>> > > +#define _ASM_RISCV_SECTIONS_H
>> > > +
>> > > +#define arch_is_kernel_data arch_is_kernel_data
>> > > +
>> > > +#include <asm-generic/sections.h>
>> > > +
>> > > +extern bool init_mem_is_free;
>> > > +
>> > > +static inline int arch_is_kernel_data(unsigned long addr)
>> > > +{
>> > > +     if (init_mem_is_free)
>> > > +             return 0;
>> > > +
>> > > +     return addr >= (unsigned long)__init_begin &&
>> > > +             addr < (unsigned long)__init_end;
>> > > +}
>> > > +#endif /* _ASM_RISCV_SECTIONS_H */
>> > > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
>> > > index 2c6dd32..9ebd5eb4 100644
>> > > --- a/arch/riscv/kernel/setup.c
>> > > +++ b/arch/riscv/kernel/setup.c
>> > > @@ -17,6 +17,7 @@
>> > >  #include <linux/sched/task.h>
>> > >  #include <linux/swiotlb.h>
>> > >  #include <linux/smp.h>
>> > > +#include <linux/poison.h>
>> > >
>> > >  #include <asm/cpu_ops.h>
>> > >  #include <asm/setup.h>
>> > > @@ -112,3 +113,11 @@ static int __init topology_init(void)
>> > >       return 0;
>> > >  }
>> > >  subsys_initcall(topology_init);
>> > > +
>> > > +bool init_mem_is_free = false;
>> > > +
>> > > +void free_initmem(void)
>> > > +{
>> > > +     free_initmem_default(POISON_FREE_INITMEM);
>> > > +     init_mem_is_free = true;
>> > > +}
>> >
>> > I'm a bit confused as to what you're trying to do here.  Yesterday I got
>> > another version of this patch set that moves init data around, today a
>> > different one.  Yesterday's is tested and simpler, and given it's so late in
>> > the process I'm inclined to take that as I don't want to break anything.
>> >
>> > Right now I have
>> >
>> > 84814460eef9 ("riscv: Fixup bootup failure with HARDENED_USERCOPY")
>> > a78c6f5956a9 ("RISC-V: Make sure memblock reserves the memory containing DT")
>> > 549738f15da0 ("Linux 5.9-rc8")
>> >
>> > Unless there's some functional bug, that's what I'm going to send out for 5.9
>> > -- I'm not all that worried about lacking the ability to free init data.  The
>> > above seems like fine 5.10 material.
>> >
>> > Let me know if I'm missing something here.
>> 84814460eef9 could resolve the problem and Atish ask for any other
>> idea? So It's another choice, I forgot RFC in prefix.
>>
>
> I prefer this fix as it is cleaner and doesn't waste memory. I have
> sent another series
> on top of this fix, that addresses the init section protections we
> talked about. All of these are definitely
> next merge window material.

Thanks, I'll take a look.

>
>> 6184358da0004c8fd940afda6c0a0fa4027dc911("riscv: Fixup static_obj()
>> fail") is a sloppy patch that introduces another problem. Sorry about
>> that.
>>
>> --
>> Best Regards
>>  Guo Ren
>>
>> ML: https://lore.kernel.org/linux-csky/