From: Rich Felker <dalias@libc.org>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Nicholas Piggin <npiggin@gmail.com>,
libc-alpha@sourceware.org, libc-dev@lists.llvm.org,
linuxppc-dev@lists.ozlabs.org, musl@lists.openwall.com
Subject: Re: [musl] Powerpc Linux 'scv' system call ABI proposal take 2
Date: Thu, 23 Apr 2020 12:18:41 -0400 [thread overview]
Message-ID: <20200423161841.GU11469@brightrain.aerifal.cx> (raw)
In-Reply-To: <a972a0e4-25bd-9cf5-75ec-2eb993ef1b6a@linaro.org>
On Thu, Apr 23, 2020 at 09:13:57AM -0300, Adhemerval Zanella wrote:
>
>
> On 22/04/2020 23:36, Rich Felker wrote:
> > On Wed, Apr 22, 2020 at 04:18:36PM +1000, Nicholas Piggin wrote:
> >> Yeah I had a bit of a play around with musl (which is very nice code I
> >> must say). The powerpc64 syscall asm is missing ctr clobber by the way.
> >> Fortunately adding it doesn't change code generation for me, but it
> >> should be fixed. glibc had the same bug at one point I think (probably
> >> due to syscall ABI documentation not existing -- something now lives in
> >> linux/Documentation/powerpc/syscall64-abi.rst).
> >
> > Do you know anywhere I can read about the ctr issue, possibly the
> > relevant glibc bug report? I'm not particularly familiar with ppc
> > register file (at least I have to refamiliarize myself every time I
> > work on this stuff) so it'd be nice to understand what's
> > potentially-wrong now.
>
> My understanding is the ctr issue only happens for vDSO calls where it
> fallback to a syscall in case an error (invalid argument, etc. and
> assuming if vDSO does not fallback to a syscall it always succeed).
> This makes the vDSO call on powerpc to have same same ABI constraint
> as a syscall, where it clobbers CR0.
I think you mean "vsyscall", the old thing glibc used where there are
in-userspace implementations of some syscalls with call interfaces
roughly equivalent to a syscall. musl has never used this. It only
uses the actual exported functions from the vdso which have normal
external function call ABI.
Rich
next prev parent reply other threads:[~2020-04-23 16:18 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 21:45 Nicholas Piggin
2020-04-15 22:55 ` [musl] " Rich Felker
2020-04-16 0:16 ` Nicholas Piggin
2020-04-16 0:48 ` Rich Felker
2020-04-16 2:24 ` Nicholas Piggin
2020-04-16 2:35 ` Rich Felker
2020-04-16 2:53 ` Nicholas Piggin
2020-04-16 3:03 ` Rich Felker
2020-04-16 3:41 ` Nicholas Piggin
2020-04-16 20:18 ` Florian Weimer
2020-04-16 9:58 ` Szabolcs Nagy
2020-04-20 0:27 ` Nicholas Piggin
2020-04-20 1:29 ` Rich Felker
2020-04-20 2:08 ` Nicholas Piggin
2020-04-20 21:17 ` Szabolcs Nagy
2020-04-21 9:57 ` Florian Weimer
2020-04-16 15:21 ` Jeffrey Walton
2020-04-16 15:40 ` Rich Felker
2020-04-16 4:48 ` Florian Weimer
2020-04-16 15:35 ` Rich Felker
2020-04-16 16:42 ` Florian Weimer
2020-04-16 16:52 ` Rich Felker
2020-04-16 18:12 ` Florian Weimer
2020-04-16 23:02 ` Segher Boessenkool
2020-04-17 0:34 ` Rich Felker
2020-04-17 1:48 ` Segher Boessenkool
2020-04-17 8:34 ` Florian Weimer
2020-04-16 14:16 ` Adhemerval Zanella
2020-04-16 15:37 ` Rich Felker
2020-04-16 17:50 ` Adhemerval Zanella
2020-04-16 17:59 ` Rich Felker
2020-04-16 18:18 ` Adhemerval Zanella
2020-04-16 18:31 ` Rich Felker
2020-04-16 18:44 ` Rich Felker
2020-04-16 18:52 ` Adhemerval Zanella
2020-04-20 0:46 ` Nicholas Piggin
2020-04-20 1:10 ` Nicholas Piggin
2020-04-20 1:34 ` Rich Felker
2020-04-20 2:32 ` Nicholas Piggin
2020-04-20 4:09 ` Rich Felker
2020-04-20 4:31 ` Nicholas Piggin
2020-04-20 17:27 ` Rich Felker
2020-04-22 6:18 ` Nicholas Piggin
2020-04-22 6:29 ` Nicholas Piggin
2020-04-23 2:36 ` Rich Felker
2020-04-23 12:13 ` Adhemerval Zanella
2020-04-23 16:18 ` Rich Felker [this message]
2020-04-23 16:35 ` Adhemerval Zanella
2020-04-23 16:43 ` Rich Felker
2020-04-23 17:15 ` Adhemerval Zanella
2020-04-23 17:42 ` Rich Felker
2020-04-25 3:40 ` Nicholas Piggin
2020-04-25 4:52 ` Rich Felker
2020-04-25 3:30 ` Nicholas Piggin
2020-04-21 12:28 ` David Laight
2020-04-21 14:39 ` Rich Felker
2020-04-21 15:00 ` Adhemerval Zanella
2020-04-21 15:31 ` David Laight
2020-04-22 6:54 ` Nicholas Piggin
2020-04-22 7:15 ` [musl] " Florian Weimer
2020-04-22 7:31 ` Nicholas Piggin
2020-04-22 8:11 ` Florian Weimer
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