Re: [PATCH 13/17] arm64: entry: move common el0 entry/return work to C

From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com,
	will@kernel.org, james.morse@arm.com
Cc: keescook@chromium.org, maz@kernel.org, broonie@kernel.org,
	labbott@redhat.com, robin.murphy@arm.com,
	julien.thierry.kdev@gmail.com, alex.popov@linux.com
Subject: Re: [PATCH 13/17] arm64: entry: move common el0 entry/return work to C
Date: Thu, 9 Jan 2020 15:19:56 +0000	[thread overview]
Message-ID: <20200109151956.GG3112@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <20200108185634.1163-14-mark.rutland@arm.com>

On Wed, Jan 08, 2020 at 06:56:30PM +0000, Mark Rutland wrote:
> Portions of common EL0 exception entry/return logic are handled in C
> while other parts are handled in assembly. Let's migrate the bulk of it
> to C so that it's easier to follow and maintain.
> 
> This patch moves the ret_to_user/work_pending logic to C. As that
> handled enabling singlestep for userspace, the matching disable is
> similarly factored out of the entry code. Additionally user_enter() is
> factored out of kernel_exit as all the corresponding user_enter() calls
> have already been converted to C.
> 
> Rather than add tedious boilerplate to each top-level exception handler
> to perform this entry/return work, a new EL0_HANDLER() handles this
> automatically. This takes the full name of each handler to keep them
> easy to find with grep, and also takes a name for the pt_regs argument
> so that we don't have a confusing implicit variable.
> 
> Since local_daif_mask() handles the GIC priority, we don't need to mess
> with this explicitly as we did in the old assembly, and the now unused
> gic_prio_kentry_setup macro can be removed.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: Will Deacon <will@kernel.org>
> ---
>  arch/arm64/include/asm/assembler.h | 18 ----------
>  arch/arm64/include/asm/exception.h |  1 +
>  arch/arm64/kernel/entry-common.c   | 67 +++++++++++++++++++++++++++++++++-----
>  arch/arm64/kernel/entry.S          | 56 ++-----------------------------
>  arch/arm64/kernel/signal.c         |  3 +-
>  5 files changed, 64 insertions(+), 81 deletions(-)

> diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
> index 220a7c3971d8..7f367d720ca4 100644
> --- a/arch/arm64/include/asm/exception.h
> +++ b/arch/arm64/include/asm/exception.h
> @@ -52,5 +52,6 @@ void do_el0_svc_compat(struct pt_regs *regs);
>  void do_el0_ia_bp_hardening(unsigned long addr,  unsigned int esr,
>  			    struct pt_regs *regs);
>  void do_serror(struct pt_regs *regs, unsigned int esr);
> +void do_notify_resume(struct pt_regs *regs,  unsigned long thread_flags);

I've just realised it's probably better to move do_notify_resume() into
entry-common.c and make it static, so I'll spin a preparatory patch
which moves it.

Thanks,
Mark.

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