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From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Matthew Helsley <mhelsley@vmware.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jason Baron <jbaron@akamai.com>, Jiri Kosina <jkosina@suse.cz>,
	ard.biesheuvel@linaro.org, Andy Lutomirski <luto@kernel.org>
Subject: Re: [POC][RFC][PATCH 1/2] jump_function: Addition of new feature "jump_function"
Date: Sat, 6 Oct 2018 14:12:11 +0200	[thread overview]
Message-ID: <20181006121211.GA5663@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181006015720.634688468@goodmis.org>

On Fri, Oct 05, 2018 at 09:51:11PM -0400, Steven Rostedt wrote:
> +#define arch_dynfunc_trampoline(name, def)	\
> +	asm volatile (				\
> +	".globl dynfunc_" #name "; \n\t"	\
> +	"dynfunc_" #name ": \n\t"		\
> +	"jmp " #def " \n\t"			\
> +	".balign 8 \n \t"			\
> +	: : : "memory" )

Bah, what is it with you people and trampolines. Why can't we, just like
jump_label, patch the call directly?

The whole call+jmp thing is silly, don't do that. It just wrecks I$ and
is slower for no real reason afaict.

Steve, also see:

  https://lkml.kernel.org/r/20181005081333.15018-1-ard.biesheuvel@linaro.org

  parent reply	other threads:[~2018-10-06 12:12 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-06  1:51 [POC][RFC][PATCH 0/2] PROOF OF CONCEPT: Dynamic Functions (jump functions) Steven Rostedt
2018-10-06  1:51 ` [POC][RFC][PATCH 1/2] jump_function: Addition of new feature "jump_function" Steven Rostedt
2018-10-06  2:00   ` Steven Rostedt
2018-10-06  2:02   ` Steven Rostedt
2018-10-06  2:03   ` Steven Rostedt
2018-10-06 15:15     ` Steven Rostedt
2018-10-06 12:12   ` Peter Zijlstra [this message]
2018-10-06 13:39     ` Steven Rostedt
2018-10-06 15:13       ` Andy Lutomirski
2018-10-06 15:16         ` Steven Rostedt
2018-10-08  7:21       ` Peter Zijlstra
2018-10-08  8:33         ` Andy Lutomirski
2018-10-08 15:57           ` Peter Zijlstra
2018-10-08 16:29             ` Andy Lutomirski
2018-10-08 16:39               ` Steven Rostedt
2018-10-08 16:39               ` Peter Zijlstra
2018-10-08 17:25                 ` Andy Lutomirski
2018-10-08 17:30                   ` Ard Biesheuvel
2018-10-08 17:42                     ` Andy Lutomirski
2018-10-08 17:44                     ` Jiri Kosina
2018-10-08 17:45                       ` Ard Biesheuvel
2018-10-08 17:47                       ` Andy Lutomirski
2018-10-09  2:17               ` Josh Poimboeuf
2018-10-09  3:57                 ` Steven Rostedt
2018-10-10 17:52                   ` Josh Poimboeuf
2018-10-10 18:03                     ` Andy Lutomirski
2018-10-10 18:16                       ` Josh Poimboeuf
2018-10-10 18:17                         ` Josh Poimboeuf
2018-10-10 21:13                           ` Andy Lutomirski
2018-10-11  3:07                             ` Josh Poimboeuf
2018-10-11 12:52                               ` Josh Poimboeuf
2018-10-11 16:20                                 ` Andy Lutomirski
2018-10-10 18:33                         ` Josh Poimboeuf
2018-10-10 18:56                           ` Steven Rostedt
2018-10-10 20:16                             ` Josh Poimboeuf
2018-10-10 20:57                               ` Andy Lutomirski
2018-10-08 16:31             ` Steven Rostedt
2018-10-08 11:30       ` Ard Biesheuvel
2018-10-09  3:44   ` Masami Hiramatsu
2018-10-09  3:55     ` Steven Rostedt
2018-10-09 16:04       ` Masami Hiramatsu
2018-10-09  8:59     ` David Laight
2018-10-06  1:51 ` [POC][RFC][PATCH 2/2] tracepoints: Implement it with dynamic functions Steven Rostedt

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