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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>, ajd@linux.ibm.com,
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Subject: Re: [GIT PULL] Please pull powerpc/linux.git powerpc-6.1-1 tag
In-Reply-To: <Y0R6fcvgGA858TQA@zx2c4.com>
References: <87edvhntv0.fsf@mpe.ellerman.id.au> <Y0RxpSFyn9m68zIb@zx2c4.com>
 <Y0R6fcvgGA858TQA@zx2c4.com>
Date:   Tue, 11 Oct 2022 12:53:17 +1100
Message-ID: <874jwbnn1u.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
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Precedence: bulk

"Jason A. Donenfeld" <Jason@zx2c4.com> writes:
> On Mon, Oct 10, 2022 at 01:25:25PM -0600, Jason A. Donenfeld wrote:
>> Hi Michael,
>> 
>> On Sun, Oct 09, 2022 at 10:01:39PM +1100, Michael Ellerman wrote:
>> > powerpc updates for 6.1
>> > 
>> >  - Remove our now never-true definitions for pgd_huge() and p4d_leaf().
>> > 
>> >  - Add pte_needs_flush() and huge_pmd_needs_flush() for 64-bit.
>> > 
>> >  - Add support for syscall wrappers.
>> > 
>> >  - Add support for KFENCE on 64-bit.
>> > 
>> >  - Update 64-bit HV KVM to use the new guest state entry/exit accounting API.
>> > 
>> >  - Support execute-only memory when using the Radix MMU (P9 or later).
>> > 
>> >  - Implement CONFIG_PARAVIRT_TIME_ACCOUNTING for pseries guests.
>> > 
>> >  - Updates to our linker script to move more data into read-only sections.
>> > 
>> >  - Allow the VDSO to be randomised on 32-bit.
>> > 
>> >  - Many other small features and fixes.
>> 
>> FYI, something in here broke the wireguard test suite, which runs the
>> iperf3 networking utility. The full log is here [1], but the relevant part
>> is: 
>> 
>> [+] NS1: iperf3 -Z -t 3 -c 192.168.241.2
>> Connecting to host 192.168.241.2, port 5201
>> iperf3: error - failed to read /dev/urandom: Bad address
>> 
>> I'll see if I can narrow it down a bit more and bisect. But just FYI, in
>> case you have an intuition.
>
> Huh. From iov_iter.c:
>
> static int copyout(void __user *to, const void *from, size_t n)
> {
>         size_t before = n;
>         if (should_fail_usercopy())
>                 return n;
>         if (access_ok(to, n)) {
>                 instrument_copy_to_user(to, from, n);
>                 n = raw_copy_to_user(to, from, n);
>                 if (n == before)
>                         pr_err("SARU n still %zu pointer is %lx\n", n, (unsigned long)to);
>         }
>         return n;
> }
>
> I added the pr_err() there to catch the failure:
> [    3.443506] SARU n still 64 pointer is b78db000
>
> Also I managed to extract the failing portion of iperf3 into something
> smaller:
>
>         int temp;
>         char *x;
>         ssize_t l;
>         FILE *f;
>         char template[] = "/blah-XXXXXX";
>
>         temp = mkstemp(template);
>         if (temp < 0)
>                 panic("mkstemp");
>         if (unlink(template) < 0)
>                 panic("unlink");
>         if (ftruncate(temp, 0x20000) < 0)
>                 panic("ftruncate");
>         x = mmap(NULL, 0x20000, PROT_READ|PROT_WRITE, MAP_PRIVATE, temp, 0);
>         if (x == MAP_FAILED)
>                 panic("mmap");
>         f = fopen("/dev/urandom", "rb");
>         if (!f)
>                 panic("fopen");
>         setbuf(f, NULL);
>         if (fread(x, 1, 0x20000, f) != 0x20000)
>                 panic("fread");

Does that fail for you reliably?

It succeeds for me running under qemu ppce500, though I'm not using your
kernel config yet.

cheers