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From:   ebiederm@xmission.com (Eric W. Biederman)
To:     Marco Elver <elver@google.com>
Cc:     Arnd Bergmann <arnd@arndb.de>, Florian Weimer <fweimer@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Collingbourne <pcc@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        sparclinux <sparclinux@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        kasan-dev <kasan-dev@googlegroups.com>
References: <YIpkvGrBFGlB5vNj@elver.google.com>
        <m11rat9f85.fsf@fess.ebiederm.org>
        <CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com>
        <m15z031z0a.fsf@fess.ebiederm.org> <YIxVWkT03TqcJLY3@elver.google.com>
        <m1zgxfs7zq.fsf_-_@fess.ebiederm.org>
        <m1o8dvs7s7.fsf_-_@fess.ebiederm.org>
        <CANpmjNNhd+qAy7tPSu=08_y-BZiowKigVkOh6HnXsxhWYuFpJA@mail.gmail.com>
Date:   Sun, 02 May 2021 13:24:46 -0500
In-Reply-To: <CANpmjNNhd+qAy7tPSu=08_y-BZiowKigVkOh6HnXsxhWYuFpJA@mail.gmail.com>
        (Marco Elver's message of "Sat, 1 May 2021 12:33:27 +0200")
Message-ID: <m1sg35ngcx.fsf@fess.ebiederm.org>
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Subject: Re: [PATCH 2/3] signal: Implement SIL_FAULT_TRAPNO
Precedence: bulk

Marco Elver <elver@google.com> writes:

> On Sat, 1 May 2021 at 00:54, Eric W. Biederman <ebiederm@xmission.com> wrote:
>>
>> Now that si_trapno is part of the union in _si_fault and available on
>> all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to
>> return SIL_FAULT_TRAPNO when si_trapno is actually used.
>>
>> Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO
>> and have the same code ignore si_trapno in in all other cases.
>>
>> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
>> ---
>>  fs/signalfd.c          |  7 ++-----
>>  include/linux/signal.h |  1 +
>>  kernel/signal.c        | 36 ++++++++++++++----------------------
>>  3 files changed, 17 insertions(+), 27 deletions(-)
>>
>> diff --git a/fs/signalfd.c b/fs/signalfd.c
>> index 040a1142915f..126c681a30e7 100644
>> --- a/fs/signalfd.c
>> +++ b/fs/signalfd.c
>> @@ -123,15 +123,12 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>>                  */
>>         case SIL_FAULT:
>>                 new.ssi_addr = (long) kinfo->si_addr;
>> -#ifdef __ARCH_SI_TRAPNO
>> +       case SIL_FAULT_TRAPNO:
>> +               new.ssi_addr = (long) kinfo->si_addr;
>>                 new.ssi_trapno = kinfo->si_trapno;
>> -#endif
>>                 break;
>>         case SIL_FAULT_MCEERR:
>>                 new.ssi_addr = (long) kinfo->si_addr;
>> -#ifdef __ARCH_SI_TRAPNO
>> -               new.ssi_trapno = kinfo->si_trapno;
>> -#endif
>>                 new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
>>                 break;
>>         case SIL_PERF_EVENT:
>> diff --git a/include/linux/signal.h b/include/linux/signal.h
>> index 1e98548d7cf6..5160fd45e5ca 100644
>> --- a/include/linux/signal.h
>> +++ b/include/linux/signal.h
>> @@ -40,6 +40,7 @@ enum siginfo_layout {
>>         SIL_TIMER,
>>         SIL_POLL,
>>         SIL_FAULT,
>> +       SIL_FAULT_TRAPNO,
>>         SIL_FAULT_MCEERR,
>>         SIL_FAULT_BNDERR,
>>         SIL_FAULT_PKUERR,
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index c3017aa8024a..7b2d61cb7411 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -1194,6 +1194,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
>>         case SIL_TIMER:
>>         case SIL_POLL:
>>         case SIL_FAULT:
>> +       case SIL_FAULT_TRAPNO:
>>         case SIL_FAULT_MCEERR:
>>         case SIL_FAULT_BNDERR:
>>         case SIL_FAULT_PKUERR:
>> @@ -2527,6 +2528,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
>>  {
>>         switch (siginfo_layout(ksig->sig, ksig->info.si_code)) {
>>         case SIL_FAULT:
>> +       case SIL_FAULT_TRAPNO:
>>         case SIL_FAULT_MCEERR:
>>         case SIL_FAULT_BNDERR:
>>         case SIL_FAULT_PKUERR:
>> @@ -3206,6 +3208,12 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
>>                         if ((sig == SIGBUS) &&
>>                             (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
>>                                 layout = SIL_FAULT_MCEERR;
>> +                       else if (IS_ENABLED(ALPHA) &&
>> +                                ((sig == SIGFPE) ||
>> +                                 ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
>> +                               layout = SIL_FAULT_TRAPNO;
>> +                       else if (IS_ENABLED(SPARC) && (sig == SIGILL) && (si_code == ILL_ILLTRP))
>> +                               layout = SIL_FAULT_TRAPNO;
>
> The breakage isn't apparent here, but in later patches. These need to
> become CONFIG_SPARC and CONFIG_ALPHA.

Good catch.  For some reason I thought IS_ENABLED added the CONFIG_
prefix but I looked and it doesn't.


>>                         else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
>>                                 layout = SIL_FAULT_BNDERR;
>>  #ifdef SEGV_PKUERR
>> @@ -3317,30 +3325,22 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>>                 break;
>>         case SIL_FAULT:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> +               break;
>> +       case SIL_FAULT_TRAPNO:
>> +               to->si_addr = ptr_to_compat(from->si_addr);
>>                 to->si_trapno = from->si_trapno;
>> -#endif
>>                 break;
>>         case SIL_FAULT_MCEERR:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_addr_lsb = from->si_addr_lsb;
>>                 break;
>>         case SIL_FAULT_BNDERR:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_lower = ptr_to_compat(from->si_lower);
>>                 to->si_upper = ptr_to_compat(from->si_upper);
>>                 break;
>>         case SIL_FAULT_PKUERR:
>>                 to->si_addr = ptr_to_compat(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_pkey = from->si_pkey;
>>                 break;
>>         case SIL_PERF_EVENT:
>> @@ -3401,30 +3401,22 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>>                 break;
>>         case SIL_FAULT:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> +               break;
>> +       case SIL_FAULT_TRAPNO:
>> +               to->si_addr = compat_ptr(from->si_addr);
>>                 to->si_trapno = from->si_trapno;
>> -#endif
>>                 break;
>>         case SIL_FAULT_MCEERR:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_addr_lsb = from->si_addr_lsb;
>>                 break;
>>         case SIL_FAULT_BNDERR:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_lower = compat_ptr(from->si_lower);
>>                 to->si_upper = compat_ptr(from->si_upper);
>>                 break;
>>         case SIL_FAULT_PKUERR:
>>                 to->si_addr = compat_ptr(from->si_addr);
>> -#ifdef __ARCH_SI_TRAPNO
>> -               to->si_trapno = from->si_trapno;
>> -#endif
>>                 to->si_pkey = from->si_pkey;
>>                 break;
>>         case SIL_PERF_EVENT:
>> --
>> 2.30.1