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Date:   Thu, 1 Jun 2023 12:30:50 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Mike Rapoport <rppt@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
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        Dinh Nguyen <dinguyen@kernel.org>,
        Heiko Carstens <hca@linux.ibm.com>,
        Helge Deller <deller@gmx.de>,
        Huacai Chen <chenhuacai@kernel.org>,
        Kent Overstreet <kent.overstreet@linux.dev>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Russell King <linux@armlinux.org.uk>,
        Song Liu <song@kernel.org>,
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Subject: Re: [PATCH 12/13] x86/jitalloc: prepare to allocate exectuatble
 memory as ROX
Message-ID: <20230601103050.GT4253@hirez.programming.kicks-ass.net>
References: <20230601101257.530867-1-rppt@kernel.org>
 <20230601101257.530867-13-rppt@kernel.org>
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On Thu, Jun 01, 2023 at 01:12:56PM +0300, Mike Rapoport wrote:

> +static void __init_or_module do_text_poke(void *addr, const void *opcode, size_t len)
> +{
> +	if (system_state < SYSTEM_RUNNING) {
> +		text_poke_early(addr, opcode, len);
> +	} else {
> +		mutex_lock(&text_mutex);
> +		text_poke(addr, opcode, len);
> +		mutex_unlock(&text_mutex);
> +	}
> +}

So I don't much like do_text_poke(); why?

> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index aa99536b824c..d50595f2c1a6 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -118,10 +118,13 @@ ftrace_modify_code_direct(unsigned long ip, const char *old_code,
>  		return ret;
>  
>  	/* replace the text with the new text */
> -	if (ftrace_poke_late)
> +	if (ftrace_poke_late) {
>  		text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL);
> -	else
> -		text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE);
> +	} else {
> +		mutex_lock(&text_mutex);
> +		text_poke((void *)ip, new_code, MCOUNT_INSN_SIZE);
> +		mutex_unlock(&text_mutex);
> +	}
>  	return 0;
>  }

And in the above case it's actively wrong for loosing the _queue()
thing.