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[Bug translator/10208] Support probing glibc synthesized syscall wrappers
- From: "fche at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 27 May 2009 15:06:01 -0000
- Subject: [Bug translator/10208] Support probing glibc synthesized syscall wrappers
- References: <20090527142638.10208.mjw@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From fche at redhat dot com 2009-05-27 15:06 -------
It turns out there is no dwarf data for chown in glibc.
That's because many of the syscall wrappers are not written
in ordinary C code, but instead generated (assembly) code:
make[2]: Entering directory `/home/fche/Private/DEVEL/DEVEL-sourceware/glibc/io'
(echo '#include <sysdep.h>'; \
echo 'PSEUDO (__libc_chown, chown, 3)'; \
echo ' ret'; \
echo 'PSEUDO_END(__libc_chown)'; \
echo 'libc_hidden_def (__libc_chown)'; \
echo 'weak_alias (__libc_chown, __chown)'; \
echo 'libc_hidden_weak (__chown)'; \
echo 'weak_alias (__libc_chown, chown)'; \
echo 'libc_hidden_weak (chown)'; \
) | gcc -c -I../include -I[...] -I.. -I../libio -I. -I
/lib/modules/2.6.27.12-78.2.8.fc9.x86_64.debug/build/include -D_LIBC_REENTRANT
-include ../include/libc-symbols.h -DASSEMBLER -Wa,--noexecstack -x
assembler-with-cpp -o
/home/fche/Private/DEVEL/DEVEL-sourceware/glibc/BUILD/io/chown.o -
objdump -dr chown.o
chown.o: file format elf64-x86-64
Disassembly of section .text:
0000000000000000 <__libc_chown>:
0: b8 5c 00 00 00 mov $0x5c,%eax
5: 0f 05 syscall
7: 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax
d: 0f 83 00 00 00 00 jae 13 <__libc_chown+0x13>
f: R_X86_64_PC32 __syscall_error-0x4
13: c3 retq
So we may have to synthesize debuginfo for these functions.
Or go debuginfo-less, and search symbol tables for plain addresses.
--
What |Removed |Added
----------------------------------------------------------------------------
Summary|Support probing weak symbol |Support probing glibc
|functions |synthesized syscall wrappers
http://sourceware.org/bugzilla/show_bug.cgi?id=10208
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