From 84a7eb1f87c1d01b58ad887a0ab5d87abbc1c772 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 30 Jul 2021 19:07:30 -0700 Subject: Use __executable_start as the lowest address for profiling [BZ #28153] 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 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 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'csu') diff --git a/csu/gmon-start.c b/csu/gmon-start.c index b3432885b3..344606a676 100644 --- a/csu/gmon-start.c +++ b/csu/gmon-start.c @@ -52,6 +52,11 @@ extern char ENTRY_POINT[]; #endif extern char etext[]; +/* Use __executable_start as the lowest address to keep profiling records + if it provided by the linker. */ +extern const char executable_start[] asm ("__executable_start") + __attribute__ ((weak, visibility ("hidden"))); + #ifndef TEXT_START # ifdef ENTRY_POINT_DECL # define TEXT_START ENTRY_POINT @@ -92,7 +97,10 @@ __gmon_start__ (void) called = 1; /* Start keeping profiling records. */ - __monstartup ((u_long) TEXT_START, (u_long) &etext); + if (&executable_start != NULL) + __monstartup ((u_long) &executable_start, (u_long) &etext); + else + __monstartup ((u_long) TEXT_START, (u_long) &etext); /* Call _mcleanup before exiting; it will write out gmon.out from the collected data. */ -- cgit 1.4.1