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commit 84a7eb1f87c1d01b58ad887a0ab5d87abbc1c772
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Author: H.J. Lu <hjl.tools@gmail.com>
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Date: Fri Jul 30 19:07:30 2021 -0700
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Use __executable_start as the lowest address for profiling [BZ #28153]
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Glibc assumes that ENTRY_POINT is the lowest address for which we need
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to keep profiling records and BFD linker uses a linker script to place
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the input sections.
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Starting from GCC 4.6, the main function is placed in .text.startup
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section and starting from binutils 2.22, BFD linker with
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commit add44f8d5c5c05e08b11e033127a744d61c26aee
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Author: Alan Modra <amodra@gmail.com>
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Date: Thu Nov 25 03:03:02 2010 +0000
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* scripttempl/elf.sc: Group .text.exit, text.startup and .text.hot
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sections.
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places .text.startup section before .text section, which leave the main
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function out of profiling records.
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Starting from binutils 2.15, linker provides __executable_start to mark
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the lowest address of the executable. Use __executable_start as the
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lowest address to keep the main function in profiling records. This fixes
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[BZ #28153].
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Tested on Linux/x86-64, Linux/x32 and Linux/i686 as well as with
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build-many-glibcs.py.
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diff --git a/csu/gmon-start.c b/csu/gmon-start.c
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index b3432885b39071cc..344606a676c188d4 100644
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--- a/csu/gmon-start.c
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+++ b/csu/gmon-start.c
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@@ -52,6 +52,11 @@ extern char ENTRY_POINT[];
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#endif
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extern char etext[];
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+/* Use __executable_start as the lowest address to keep profiling records
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+ if it provided by the linker. */
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+extern const char executable_start[] asm ("__executable_start")
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+ __attribute__ ((weak, visibility ("hidden")));
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+
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#ifndef TEXT_START
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# ifdef ENTRY_POINT_DECL
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# define TEXT_START ENTRY_POINT
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@@ -92,7 +97,10 @@ __gmon_start__ (void)
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called = 1;
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/* Start keeping profiling records. */
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- __monstartup ((u_long) TEXT_START, (u_long) &etext);
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+ if (&executable_start != NULL)
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+ __monstartup ((u_long) &executable_start, (u_long) &etext);
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+ else
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+ __monstartup ((u_long) TEXT_START, (u_long) &etext);
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/* Call _mcleanup before exiting; it will write out gmon.out from the
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collected data. */
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diff --git a/gmon/tst-gmon-gprof.sh b/gmon/tst-gmon-gprof.sh
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index 9d371582b99677fa..dc0be021104f725d 100644
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--- a/gmon/tst-gmon-gprof.sh
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+++ b/gmon/tst-gmon-gprof.sh
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@@ -39,12 +39,14 @@ trap cleanup 0
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cat > "$expected" <
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f1 2000
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f2 1000
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+f3 1
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EOF
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# Special version for powerpc with function descriptors.
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cat > "$expected_dot" <
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.f1 2000
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.f2 1000
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+.f3 1
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EOF
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"$GPROF" -C "$program" "$data" \
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diff --git a/gmon/tst-gmon-static-gprof.sh b/gmon/tst-gmon-static-gprof.sh
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index 79218df967f9387f..4cc99c80d0115271 100644
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--- a/gmon/tst-gmon-static-gprof.sh
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+++ b/gmon/tst-gmon-static-gprof.sh
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@@ -39,6 +39,7 @@ trap cleanup 0
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cat > "$expected" <
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f1 2000
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f2 1000
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+f3 1
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main 1
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EOF
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@@ -46,6 +47,7 @@ EOF
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cat > "$expected_dot" <
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.f1 2000
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.f2 1000
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+.f3 1
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.main 1
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EOF
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