linux-kernel - Re: [v4 PATCH 8/8] RISC-V: Assign hwcap as per comman capabilities.

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Message-ID: <20190212112534.GB28278@localhost>
Date:   Tue, 12 Feb 2019 12:25:34 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Atish Patra <atish.patra@....com>
Cc:     linux-riscv@...ts.infradead.org, Alan Kao <alankao@...estech.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andreas Schwab <schwab@...e.de>,
        Anup Patel <anup@...infault.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        Jason Cooper <jason@...edaemon.net>,
        Johan Hovold <johan@...nel.org>, linux-kernel@...r.kernel.org,
        Marc Zyngier <marc.zyngier@....com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Rob Herring <robh@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [v4 PATCH 8/8] RISC-V: Assign hwcap as per comman capabilities.

On Tue, Feb 12, 2019 at 03:10:12AM -0800, Atish Patra wrote:
> Currently, we set hwcap based on first valid hart from DT. This may not
> be correct always as that hart might not be current booting cpu or may
> have a different capability.
> 
> Set hwcap as the capabilities supported by all possible harts with "okay"
> status.
> 
> Signed-off-by: Atish Patra <atish.patra@....com>
> ---
>  arch/riscv/kernel/cpufeature.c | 41 ++++++++++++++++++++++-------------------
>  1 file changed, 22 insertions(+), 19 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index e7a4701f..a1e4fb34 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -20,6 +20,7 @@
>  #include <linux/of.h>
>  #include <asm/processor.h>
>  #include <asm/hwcap.h>
> +#include <asm/smp.h>
>  
>  unsigned long elf_hwcap __read_mostly;
>  #ifdef CONFIG_FPU
> @@ -42,28 +43,30 @@ void riscv_fill_hwcap(void)
>  
>  	elf_hwcap = 0;
>  
> -	/*
> -	 * We don't support running Linux on hertergenous ISA systems.  For
> -	 * now, we just check the ISA of the first "okay" processor.
> -	 */
>  	for_each_of_cpu_node(node) {
> -		if (riscv_of_processor_hartid(node) >= 0)
> -			break;
> -	}
> -	if (!node) {
> -		pr_warn("Unable to find \"cpu\" devicetree entry\n");
> -		return;
> -	}
> +		unsigned long this_hwcap = 0;
>  
> -	if (of_property_read_string(node, "riscv,isa", &isa)) {
> -		pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
> -		of_node_put(node);
> -		return;
> -	}
> -	of_node_put(node);
> +		if (riscv_of_processor_hartid(node) < 0)
> +			continue;
>  
> -	for (i = 0; i < strlen(isa); ++i)
> -		elf_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
> +		if (of_property_read_string(node, "riscv,isa", &isa)) {
> +			pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
> +			return;

Did you want "continue" here to continue processing the other harts?

Note that you currently leak the device node when returning.

Johan