linux-kernel - Re: [PATCH 0/6] Final si

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Date:   Fri, 16 Jul 2021 13:50:04 +0200
From:   Marco Elver <elver@...gle.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Florian Weimer <fweimer@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Collingbourne <pcc@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        sparclinux <sparclinux@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: [PATCH 0/6] Final si_trapno bits

On Thu, Jul 15, 2021 at 01:09PM -0500, Eric W. Biederman wrote:
> As a part of a fix for the ABI of the newly added SIGTRAP TRAP_PERF a
> si_trapno was reduced to an ordinary extention of the _sigfault case
> of struct siginfo.
> 
> When Linus saw the complete set of changes come in as a fix he requested
> that the set of changes be trimmed down to just what was necessary to
> fix the SIGTRAP TRAP_PERF ABI.
> 
> I had intended to get the rest of the changes into the merge window for
> v5.14 but I dropped the ball.
> 
> I have made the changes to stop using __ARCH_SI_TRAPNO be per
> architecture so they are easier to review.  In doing so I found one
> place on alpha where I used send_sig_fault instead of
> send_sig_fault_trapno(... si_trapno = 0).  That would not have changed
> the userspace behavior but it did make the kernel code less clear.
> 
> My rule in these patches is everywhere that siginfo layout calls
> for SIL_FAULT_TRAPNO the code uses either force_sig_fault_trapno
> or send_sig_fault_trapno.
> 
> And of course I have rebased and compile tested Marco's compile time
> assert patches.
> 
> Eric
> 
> 
> Eric W. Biederman (3):
>       signal/sparc: si_trapno is only used with SIGILL ILL_ILLTRP
>       signal/alpha: si_trapno is only used with SIGFPE and SIGTRAP TRAP_UNK
>       signal: Remove the generic __ARCH_SI_TRAPNO support
> 
> Marco Elver (3):
>       sparc64: Add compile-time asserts for siginfo_t offsets
>       arm: Add compile-time asserts for siginfo_t offsets
>       arm64: Add compile-time asserts for siginfo_t offsets

Nice, thanks for the respin. If I diffed it right, I see this is almost
(modulo what you mentioned above) equivalent to:
  https://lore.kernel.org/linux-api/m1tuni8ano.fsf_-_@fess.ebiederm.org/
+ what's already in mainline. It's only missing:

	signal: Verify the alignment and size of siginfo_t
	signal: Rename SIL_PERF_EVENT SIL_FAULT_PERF_EVENT for consistency

Would this be appropriate for this series, or rather separately, or
dropped completely?

Thanks,
-- Marco