Re: [PATCH] arm64: ftrace: fix function_graph tracer panic

From	Catalin Marinas <catalin.marinas@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] arm64: ftrace: fix function_graph tracer panic
Date	2015-10-02 14:50 +0200
Message-ID	<qf7WG-3Cy-19@gated-at.bofh.it> (permalink)
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On Fri, Oct 02, 2015 at 04:56:48PM +0900, AKASHI Takahiro wrote:
> >>On 09/30/2015 11:49 AM, Li Bin wrote:
> >>>This is because when using function graph tracer, if the traced
> >>>function return value is in multi regs ([0x-07]), return_to_handler
> 
> typo: 0x-07 => x0-x7

I fixed this up.

> and pre/post-indexed addressing stp&ldp may save add&sub instructions, but
> it's a matter of preference.

Doing it this way is more efficient in general as it avoids updating the
sp and writing in reverse order. That's the reason we recently changed
the kernel_entry/exit macros (see commit 63648dd20fa0 "arm64: entry:
use ldp/stp instead of push/pop when saving/restoring regs").

Thanks.

-- 
Catalin
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[PATCH] arm64: ftrace: fix function_graph tracer panic Li Bin <huawei.libin@huawei.com> - 2015-09-30 05:00 +0200
  Re: [PATCH] arm64: ftrace: fix function_graph tracer panic AKASHI Takahiro <takahiro.akashi@linaro.org> - 2015-10-01 08:20 +0200
    Re: [PATCH] arm64: ftrace: fix function_graph tracer panic Catalin Marinas <catalin.marinas@arm.com> - 2015-10-01 17:30 +0200
      Re: [PATCH] arm64: ftrace: fix function_graph tracer panic AKASHI Takahiro <takahiro.akashi@linaro.org> - 2015-10-02 10:00 +0200
        Re: [PATCH] arm64: ftrace: fix function_graph tracer panic Catalin Marinas <catalin.marinas@arm.com> - 2015-10-02 14:50 +0200

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