linux-kernel - Re: [PATCH -next v5 08/22] arm64: entry: Use different helpers to check resched for PREEMPT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Z6no9e7nBORuEWIK@J2N7QTR9R3>
Date: Mon, 10 Feb 2025 11:54:29 +0000
From: Mark Rutland <mark.rutland@....com>
To: Jinjie Ruan <ruanjinjie@...wei.com>
Cc: catalin.marinas@....com, will@...nel.org, oleg@...hat.com,
	sstabellini@...nel.org, tglx@...utronix.de, peterz@...radead.org,
	luto@...nel.org, mingo@...hat.com, juri.lelli@...hat.com,
	vincent.guittot@...aro.org, dietmar.eggemann@....com,
	rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
	vschneid@...hat.com, kees@...nel.org, wad@...omium.org,
	akpm@...ux-foundation.org, samitolvanen@...gle.com,
	masahiroy@...nel.org, hca@...ux.ibm.com, aliceryhl@...gle.com,
	rppt@...nel.org, xur@...gle.com, paulmck@...nel.org, arnd@...db.de,
	mbenes@...e.cz, puranjay@...nel.org, pcc@...gle.com,
	ardb@...nel.org, sudeep.holla@....com, guohanjun@...wei.com,
	rafael@...nel.org, liuwei09@...tc.cn, dwmw@...zon.co.uk,
	Jonathan.Cameron@...wei.com, liaochang1@...wei.com,
	kristina.martsenko@....com, ptosi@...gle.com, broonie@...nel.org,
	thiago.bauermann@...aro.org, kevin.brodsky@....com,
	joey.gouly@....com, liuyuntao12@...wei.com, leobras@...hat.com,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	xen-devel@...ts.xenproject.org
Subject: Re: [PATCH -next v5 08/22] arm64: entry: Use different helpers to
 check resched for PREEMPT_DYNAMIC

On Fri, Dec 06, 2024 at 06:17:30PM +0800, Jinjie Ruan wrote:
> In generic entry, when PREEMPT_DYNAMIC is enabled or disabled, two
> different helpers are used to check whether resched is required
> and some common code is reused.
> 
> In preparation for moving arm64 over to the generic entry code,
> use new helper to check resched when PREEMPT_DYNAMIC enabled and
> reuse common code for the disabled case.
> 
> No functional changes.

Please fold this together with the last two patches; it's undoing
changes you made in patch 6, and it'd be far clearer to see that all at
once.

Mark.

> 
> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
> ---
>  arch/arm64/include/asm/preempt.h |  3 +++
>  arch/arm64/kernel/entry-common.c | 21 +++++++++++----------
>  2 files changed, 14 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h
> index d0f93385bd85..0f0ba250efe8 100644
> --- a/arch/arm64/include/asm/preempt.h
> +++ b/arch/arm64/include/asm/preempt.h
> @@ -93,11 +93,14 @@ void dynamic_preempt_schedule(void);
>  #define __preempt_schedule()		dynamic_preempt_schedule()
>  void dynamic_preempt_schedule_notrace(void);
>  #define __preempt_schedule_notrace()	dynamic_preempt_schedule_notrace()
> +void dynamic_irqentry_exit_cond_resched(void);
> +#define irqentry_exit_cond_resched()	dynamic_irqentry_exit_cond_resched()
>  
>  #else /* CONFIG_PREEMPT_DYNAMIC */
>  
>  #define __preempt_schedule()		preempt_schedule()
>  #define __preempt_schedule_notrace()	preempt_schedule_notrace()
> +#define irqentry_exit_cond_resched()	raw_irqentry_exit_cond_resched()
>  
>  #endif /* CONFIG_PREEMPT_DYNAMIC */
>  #endif /* CONFIG_PREEMPTION */
> diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
> index 029f8bd72f8a..015a65d19b52 100644
> --- a/arch/arm64/kernel/entry-common.c
> +++ b/arch/arm64/kernel/entry-common.c
> @@ -75,10 +75,6 @@ static noinstr irqentry_state_t enter_from_kernel_mode(struct pt_regs *regs)
>  	return state;
>  }
>  
> -#ifdef CONFIG_PREEMPT_DYNAMIC
> -DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
> -#endif
> -
>  static inline bool arm64_need_resched(void)
>  {
>  	/*
> @@ -106,17 +102,22 @@ static inline bool arm64_need_resched(void)
>  
>  void raw_irqentry_exit_cond_resched(void)
>  {
> -#ifdef CONFIG_PREEMPT_DYNAMIC
> -	if (!static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
> -		return;
> -#endif
> -
>  	if (!preempt_count()) {
>  		if (need_resched() && arm64_need_resched())
>  			preempt_schedule_irq();
>  	}
>  }
>  
> +#ifdef CONFIG_PREEMPT_DYNAMIC
> +DEFINE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched);
> +void dynamic_irqentry_exit_cond_resched(void)
> +{
> +	if (!static_branch_unlikely(&sk_dynamic_irqentry_exit_cond_resched))
> +		return;
> +	raw_irqentry_exit_cond_resched();
> +}
> +#endif
> +
>  /*
>   * Handle IRQ/context state management when exiting to kernel mode.
>   * After this function returns it is not safe to call regular kernel code,
> @@ -140,7 +141,7 @@ static __always_inline void __exit_to_kernel_mode(struct pt_regs *regs,
>  		}
>  
>  		if (IS_ENABLED(CONFIG_PREEMPTION))
> -			raw_irqentry_exit_cond_resched();
> +			irqentry_exit_cond_resched();
>  
>  		trace_hardirqs_on();
>  	} else {
> -- 
> 2.34.1
>