Re: [PATCH 0/3] arm64/sve: UAPI: Disentangle ptrace.h from sigcontext.h

From: Szabolcs Nagy <Szabolcs.Nagy@arm.com>
To: Dave P Martin <Dave.Martin@arm.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Cc: nd <nd@arm.com>, Will Deacon <Will.Deacon@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Alan Hayward <Alan.Hayward@arm.com>
Subject: Re: [PATCH 0/3] arm64/sve: UAPI: Disentangle ptrace.h from sigcontext.h
Date: Fri, 14 Dec 2018 18:13:33 +0000	[thread overview]
Message-ID: <2abbbd29-cc87-a0ad-80b7-e2a1d039235e@arm.com> (raw)
In-Reply-To: <1544556407-19897-1-git-send-email-Dave.Martin@arm.com>

On 11/12/2018 19:26, Dave Martin wrote:
> This patch refactors the UAPI header definitions for the Arm SVE
> extension to avoid multiple-definition problems when userspace mixes its
> own sigcontext.h definitions with the kernel's ptrace.h (which is
> apparently routine).
> 
> A common backend header is created to hold common definitions, suitably
> namespaced, and with an appropriate header guard.
> 
> See the commit message in patch 3 for further explanation of why this
> is needed.
> 
> Because of the non-trivial header guard in the new sve_context.h, patch
> 1 adds support to headers_install.sh to munge #if defined(_UAPI_FOO) in
> a similar way to the current handling of #ifndef _UAPI_FOO.
> 

thanks for doing this.

the patches fix the gdb build issue on musl libc with an
additional gdb patch:
https://sourceware.org/ml/gdb-patches/2018-12/msg00152.html
(in userspace i'd expect users relying on signal.h providing
whatever is in asm/sigcontext.h.)

i think sve_context.h could be made to work with direct include,
even if that's not useful because there is no public api there.
(and then you dont need the first patch)

> Dave Martin (3):
>   kbuild: install_headers.sh: Strip _UAPI from #if-defined() guards
>   arm64/sve: ptrace: Fix SVE_PT_REGS_OFFSET definition
>   arm64/sve: Disentangle <uapi/asm/ptrace.h> from
>     <uapi/asm/sigcontext.h>
> 
>  arch/arm64/include/uapi/asm/ptrace.h      | 39 ++++++++++-----------
>  arch/arm64/include/uapi/asm/sigcontext.h  | 56 +++++++++++++++----------------
>  arch/arm64/include/uapi/asm/sve_context.h | 50 +++++++++++++++++++++++++++
>  scripts/headers_install.sh                |  1 +
>  4 files changed, 97 insertions(+), 49 deletions(-)
>  create mode 100644 arch/arm64/include/uapi/asm/sve_context.h
> 

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