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From: Borislav Petkov <bp@alien8.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	rostedt@goodmis.org, mhiramat@kernel.org, bristot@redhat.com,
	jbaron@akamai.com, torvalds@linux-foundation.org,
	tglx@linutronix.de, mingo@kernel.org, namit@vmware.com,
	hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org,
	jpoimboe@redhat.com
Subject: Re: [RESEND][PATCH v3 09/17] x86/static_call: Add out-of-line static call implementation
Date: Thu, 26 Mar 2020 15:57:09 +0100	[thread overview]
Message-ID: <20200326145709.GB11398@zn.tnic> (raw)
In-Reply-To: <20200324142245.819003994@infradead.org>

On Tue, Mar 24, 2020 at 02:56:12PM +0100, Peter Zijlstra wrote:
> +static void __static_call_transform(void *insn, u8 opcode, void *func)
> +{
> +	const void *code = text_gen_insn(opcode, (long)insn, (long)func);
> +
> +	if (WARN_ONCE(*(u8 *)insn != opcode,
> +		      "unexpected static call insn opcode 0x%x at %pS\n",
> +		      opcode, insn))
> +		return;
> +
> +	if (memcmp(insn, code, CALL_INSN_SIZE) == 0)
> +		return;
> +
> +	text_poke_bp(insn, code, CALL_INSN_SIZE, NULL);

Right, this is working with CALL_INSN_SIZE but ...

> +}
> +
> +void arch_static_call_transform(void *site, void *tramp, void *func)
> +{
> +	mutex_lock(&text_mutex);
> +
> +	if (tramp)
> +		__static_call_transform(tramp, JMP32_INSN_OPCODE, func);

... it gets called with JMP32_INSN_OPCODE too. I mean, both lengths are
equal and all - it is just a bit confusing at a first glance. Maybe slap
a small comment that it is ok.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

  reply	other threads:[~2020-03-26 14:57 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 13:56 [RESEND][PATCH v3 00/17] Add static_call() Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 01/17] notifier: Fix broken error handling pattern Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 02/17] module: Fix up module_notifier return values Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 03/17] module: Properly propagate MODULE_STATE_COMING failure Peter Zijlstra
2020-03-25 17:35   ` Jessica Yu
2020-03-27  4:51     ` Josh Poimboeuf
2020-03-27 12:04     ` Miroslav Benes
2020-03-24 13:56 ` [RESEND][PATCH v3 04/17] jump_label,module: Fix module lifetime for __jump_label_mod_text_reserved Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 05/17] compiler.h: Make __ADDRESSABLE() symbol truly unique Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 06/17] static_call: Add basic static call infrastructure Peter Zijlstra
2020-03-26 16:42   ` Nadav Amit
2020-03-26 17:01     ` Peter Zijlstra
2020-03-26 18:09       ` Nadav Amit
2020-03-26 18:28         ` Peter Zijlstra
2020-03-26 19:02           ` Nadav Amit
2020-03-26 19:13             ` Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 07/17] static_call: Add inline " Peter Zijlstra
2020-03-26 15:54   ` Borislav Petkov
2020-03-24 13:56 ` [RESEND][PATCH v3 08/17] static_call: Avoid kprobes on inline static_call()s Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 09/17] x86/static_call: Add out-of-line static call implementation Peter Zijlstra
2020-03-26 14:57   ` Borislav Petkov [this message]
2020-04-06  1:08   ` Fangrui Song
2020-04-06 11:04     ` Peter Zijlstra
2020-04-06 18:29       ` Nick Desaulniers
2020-03-24 13:56 ` [RESEND][PATCH v3 10/17] x86/static_call: Add inline static call implementation for x86-64 Peter Zijlstra
2020-03-26 15:17   ` Borislav Petkov
2020-03-26 16:06   ` Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 11/17] static_call: Simple self-test Peter Zijlstra
2020-03-26 15:44   ` Borislav Petkov
2020-03-26 17:08     ` Peter Zijlstra
2020-03-26 17:33       ` Borislav Petkov
2020-03-24 13:56 ` [RESEND][PATCH v3 12/17] tracepoint: Optimize using static_call() Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 13/17] x86/alternatives: Teach text_poke_bp() to emulate RET Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 14/17] static_call: Add static_cond_call() Peter Zijlstra
2020-03-24 16:14   ` Linus Torvalds
2020-03-24 16:22     ` Andy Lutomirski
2020-03-24 16:33       ` Linus Torvalds
2020-03-24 17:03         ` Peter Zijlstra
2020-03-25 18:13           ` Peter Zijlstra
2020-03-25 18:26             ` Linus Torvalds
2020-03-25 19:34         ` hpa
2020-03-25 20:52           ` Linus Torvalds
2020-03-25 22:07             ` Peter Zijlstra
2020-03-24 16:54     ` Peter Zijlstra
2020-03-26 23:37   ` Rasmus Villemoes
2020-03-27 10:08     ` Peter Zijlstra
2020-03-27 13:25       ` Rasmus Villemoes
2020-03-24 13:56 ` [RESEND][PATCH v3 15/17] static_call: Handle tail-calls Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 16/17] static_call: Allow early init Peter Zijlstra
2020-03-24 13:56 ` [RESEND][PATCH v3 17/17] x86/perf, static_call: Optimize x86_pmu methods Peter Zijlstra
2020-03-25 17:49 ` [RESEND][PATCH v3 00/17] Add static_call() Peter Zijlstra

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