From: Fangrui Song <maskray@google.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH v3] Use __executable_start as the lowest address for profiling [BZ #28153]
Date: Thu, 5 Aug 2021 17:16:09 -0700 [thread overview]
Message-ID: <20210806001609.x5q2zkhoo7xeaf3c@google.com> (raw)
In-Reply-To: <20210805120904.3528530-1-hjl.tools@gmail.com>
On 2021-08-05, H.J. Lu via Libc-alpha wrote:
>Glibc assumes that ENTRY_POINT is the lowest address for which we need
>to keep profiling records and BFD linker uses a linker script to place
>the input sections.
>
>Starting from GCC 4.6, the main function is placed in .text.startup
>section and starting from binutils 2.22, BFD linker with
>
>commit add44f8d5c5c05e08b11e033127a744d61c26aee
>Author: Alan Modra <amodra@gmail.com>
>Date: Thu Nov 25 03:03:02 2010 +0000
>
> * scripttempl/elf.sc: Group .text.exit, text.startup and .text.hot
> sections.
>
>places .text.startup section before .text section, which leave the main
>function out of profiling records.
>
>Starting from binutils 2.15, linker provides __executable_start to mark
>the lowest address of the executable. Use __executable_start as the
>lowest address to keep the main function in profiling records. This fixes
>[BZ #28153].
>
>Tested on Linux/x86-64, Linux/x32 and Linux/i686 as well as with
>build-many-glibcs.py.
>---
> csu/gmon-start.c | 10 +++++++++-
> gmon/tst-gmon-gprof.sh | 2 ++
> gmon/tst-gmon-static-gprof.sh | 2 ++
> 3 files changed, 13 insertions(+), 1 deletion(-)
LGTM
next prev parent reply other threads:[~2021-08-06 0:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-05 12:09 H.J. Lu
2021-08-06 0:16 ` Fangrui Song [this message]
2021-08-06 7:21 ` Fangrui Song
-- strict thread matches above, loose matches on Subject: below --
2021-07-31 15:13 [PATCH v2] Place ENTRY_POINT in .text.unlikely section " H.J. Lu
2021-07-31 16:36 ` Florian Weimer
2021-07-31 17:06 ` H.J. Lu
2021-07-31 17:11 ` Florian Weimer
2021-07-31 17:43 ` [PATCH v3] Use __executable_start as the lowest address for profiling " H.J. Lu
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