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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Nicolai Stange <nstange@suse.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Jiri Kosina <jikos@kernel.org>,
	Miroslav Benes <mbenes@suse.cz>, Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Shuah Khan <shuah@kernel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Mimi Zohar <zohar@linux.ibm.com>, Juergen Gross <jgross@suse.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nayna Jain <nayna@linux.ibm.com>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Joerg Roedel <jroedel@suse.de>,
	linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 2/4] x86/kprobes: Fix frame pointer annotations
Date: Thu, 9 May 2019 09:00:01 -0500	[thread overview]
Message-ID: <20190509140001.fvwzlnhai6ddqjmt@treble> (raw)
In-Reply-To: <20190509081431.GO2589@hirez.programming.kicks-ass.net>

On Thu, May 09, 2019 at 10:14:31AM +0200, Peter Zijlstra wrote:
> But what I'd love to do is something like the belwo patch, and make all
> the trampolines (very much including ftrace) use that. Such that we then
> only have 1 copy of this magic (well, 2 because x86_64 also needs an
> implementation of this of course).
> 
> Changing ftrace over to this would be a little more work but it can
> easily chain things a little to get its original context back:
> 
> ENTRY(ftrace_regs_caller)
> GLOBAL(ftrace_regs_func)
> 	push ftrace_stub
> 	push ftrace_regs_handler
> 	jmp call_to_exception_trampoline
> END(ftrace_regs_caller)
> 
> typedef void (*ftrace_func_t)(unsigned long, unsigned long, struct ftrace_op *, struct pt_regs *);
> 
> struct ftrace_regs_stack {
> 	ftrace_func_t func;
> 	unsigned long parent_ip;
> };
> 
> void ftrace_regs_handler(struct pr_regs *regs)
> {
> 	struct ftrace_regs_stack *st = (void *)regs->sp;
> 	ftrace_func_t func = st->func;
> 
> 	regs->sp += sizeof(long); /* pop func */
> 
> 	func(regs->ip, st->parent_ip, function_trace_op, regs);
> }
> 
> Hmm? I didn't look into the function_graph thing, but I imagine it can
> be added without too much pain.

I like this patch a lot, assuming it can be made to work for the
different users.

-- 
Josh

  parent reply	other threads:[~2019-05-09 14:00 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-08  7:49 [PATCH 0/4] x86: int3 fallout Peter Zijlstra
2019-05-08  7:49 ` [PATCH 1/4] x86/entry/32: Clean up return from interrupt preemption path Peter Zijlstra
2019-05-08  7:49 ` [PATCH 2/4] x86/kprobes: Fix frame pointer annotations Peter Zijlstra
2019-05-08 11:54   ` Josh Poimboeuf
2019-05-08 12:04     ` Peter Zijlstra
2019-05-08 12:40       ` Peter Zijlstra
2019-05-08 12:42       ` Josh Poimboeuf
2019-05-08 15:39         ` Peter Zijlstra
2019-05-08 18:48           ` Josh Poimboeuf
2019-05-09  1:20             ` Masami Hiramatsu
2019-05-09  8:14               ` Peter Zijlstra
2019-05-09  9:27                 ` Peter Zijlstra
2019-05-09 14:00                 ` Josh Poimboeuf [this message]
2019-05-09 14:01                 ` Masami Hiramatsu
2019-05-09 17:14                   ` Peter Zijlstra
2019-05-10  4:58                     ` Masami Hiramatsu
2019-05-10 12:31                       ` Peter Zijlstra
2019-05-11  0:52                         ` Masami Hiramatsu
2019-05-10 12:40                       ` Peter Zijlstra
2019-05-11  0:56                         ` Masami Hiramatsu
2019-05-13  8:15                           ` Peter Zijlstra
2019-05-09 16:20                 ` Andy Lutomirski
2019-05-09 17:18                   ` Peter Zijlstra
2019-05-09 17:43                   ` Steven Rostedt
2019-05-10  3:21                     ` Masami Hiramatsu
2019-05-10 12:14                       ` Peter Zijlstra
2019-05-10 12:17                       ` Peter Zijlstra
2019-05-10 14:54                         ` Steven Rostedt
2019-05-09 17:37                 ` Steven Rostedt
2019-05-09 18:26                   ` Peter Zijlstra
2019-05-09 18:36                     ` Steven Rostedt
2019-05-08  7:49 ` [PATCH 3/4] x86/ftrace: Add pt_regs frame annotations Peter Zijlstra
2019-05-08  7:49 ` [RFC][PATCH 4/4] x86_32: Provide consistent pt_regs Peter Zijlstra
2019-05-08 11:57   ` Josh Poimboeuf
2019-05-08 12:46     ` Ingo Molnar
2019-05-08 20:58   ` Linus Torvalds

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