linux-kernel - Re: [PATCH v6 15/17] arm64: kexec: add expandable argument to relocation function

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Date:   Mon, 14 Oct 2019 19:35:51 -0400
From:   Pavel Tatashin <pasha.tatashin@...een.com>
To:     James Morse <james.morse@....com>
Cc:     James Morris <jmorris@...ei.org>, Sasha Levin <sashal@...nel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        kexec mailing list <kexec@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        Catalin Marinas <catalin.marinas@....com>, will@...nel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Vladimir Murzin <vladimir.murzin@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Bhupesh Sharma <bhsharma@...hat.com>,
        linux-mm <linux-mm@...ck.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v6 15/17] arm64: kexec: add expandable argument to
 relocation function

> > +struct kern_reloc_arg {
> > +     unsigned long   head;
> > +     unsigned long   entry_addr;
> > +     unsigned long   kern_arg0;
> > +     unsigned long   kern_arg1;
> > +     unsigned long   kern_arg2;
> > +     unsigned long   kern_arg3;
>
> ... at least one of these should by phys_addr_t!

OK, changed them to phys_addr_t

>
> While the sizes are the same on arm64, this reminds the reader what kind of address this
> is, and lets the compiler warn you if you make a mistake.

OK

>
>
> > +};
>
> > diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
> > index 214685760e1c..900394907fd8 100644
> > --- a/arch/arm64/kernel/asm-offsets.c
> > +++ b/arch/arm64/kernel/asm-offsets.c
> > @@ -23,6 +23,7 @@
> >  #include <asm/suspend.h>
> >  #include <linux/kbuild.h>
> >  #include <linux/arm-smccc.h>
> > +#include <linux/kexec.h>
> >
> >  int main(void)
> >  {
> > @@ -126,6 +127,14 @@ int main(void)
> >  #ifdef CONFIG_ARM_SDE_INTERFACE
> >    DEFINE(SDEI_EVENT_INTREGS, offsetof(struct sdei_registered_event, interrupted_regs));
> >    DEFINE(SDEI_EVENT_PRIORITY,        offsetof(struct sdei_registered_event, priority));
> > +#endif
> > +#ifdef CONFIG_KEXEC_CORE
> > +  DEFINE(KRELOC_HEAD,                offsetof(struct kern_reloc_arg, head));
> > +  DEFINE(KRELOC_ENTRY_ADDR,  offsetof(struct kern_reloc_arg, entry_addr));
> > +  DEFINE(KRELOC_KERN_ARG0,   offsetof(struct kern_reloc_arg, kern_arg0));
> > +  DEFINE(KRELOC_KERN_ARG1,   offsetof(struct kern_reloc_arg, kern_arg1));
> > +  DEFINE(KRELOC_KERN_ARG2,   offsetof(struct kern_reloc_arg, kern_arg2));
> > +  DEFINE(KRELOC_KERN_ARG3,   offsetof(struct kern_reloc_arg, kern_arg3));
>
> Please use kexec as the prefix. The kernel also applies relocations during early boot.
> These are global values, and in isolation doesn't imply kexec.

OK
> >  .align 3     /* To keep the 64-bit values below naturally aligned. */
> > -
> >  .Lcopy_end:
> >  .org KEXEC_CONTROL_PAGE_SIZE
> >
>
> My eyes!
>
> Please don't make unnecessary changes. Its hard enough to read the assembly, moving
> whitespace, comments and re-allocating the register guarantees that no-one can work out
> what is happening.
>
> If something needs cleaning up to make the change obvious, it needs doing as a previous
> patch. Mechanical changes are fairly easy to review.
> Functional changes behind a whirlwind of mechanical changes will cause the reviewer to
> give up.

Sure, I have split this patch into several patches, and moved
clean-ups into separate patches.

Thank you,
Pasha