| Message ID | 20190816233422.16715-1-jkz@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | linux-user: Support gdb 'qOffsets' query for ELF | expand |
+cc: riku.voipio@iki.fi, I typoed the email on the first go. On Fri, Aug 16, 2019 at 4:34 PM Josh Kunz <jkz@google.com> wrote: > This is needed to support debugging PIE ELF binaries running under QEMU > user mode. Currently, `code_offset` and `data_offset` remain unset for > all ELF binaries, so GDB is unable to correctly locate the position of > the binary's text and data. > > The fields `code_offset`, and `data_offset` were originally added way > back in 2006 to support debugging of bFMT executables (978efd6aac6), > and support was just never added for ELF. Since non-PIE binaries are > loaded at exactly the address specified in the binary, GDB does not need > to relocate any symbols, so the buggy behavior is not normally observed. > > Buglink: https://bugs.launchpad.net/qemu/+bug/1528239 > Signed-off-by: Josh Kunz <jkz@google.com> > --- > linux-user/elfload.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/linux-user/elfload.c b/linux-user/elfload.c > index 3365e192eb..ceac035208 100644 > --- a/linux-user/elfload.c > +++ b/linux-user/elfload.c > @@ -2380,6 +2380,8 @@ static void load_elf_image(const char *image_name, > int image_fd, > } > > info->load_bias = load_bias; > + info->code_offset = load_bias; > + info->data_offset = load_bias; > info->load_addr = load_addr; > info->entry = ehdr->e_entry + load_bias; > info->start_code = -1; > -- > 2.23.0.rc1.153.gdeed80330f-goog > >
Patchew URL: https://patchew.org/QEMU/20190816233422.16715-1-jkz@google.com/ Hi, This series seems to have some coding style problems. See output below for more information: Type: series Subject: [Qemu-devel] [PATCH] linux-user: Support gdb 'qOffsets' query for ELF Message-id: 20190816233422.16715-1-jkz@google.com === TEST SCRIPT BEGIN === #!/bin/bash git rev-parse base > /dev/null || exit 0 git config --local diff.renamelimit 0 git config --local diff.renames True git config --local diff.algorithm histogram ./scripts/checkpatch.pl --mailback base.. === TEST SCRIPT END === Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384 From https://github.com/patchew-project/qemu * [new tag] patchew/20190816233422.16715-1-jkz@google.com -> patchew/20190816233422.16715-1-jkz@google.com Submodule 'capstone' (https://git.qemu.org/git/capstone.git) registered for path 'capstone' Submodule 'dtc' (https://git.qemu.org/git/dtc.git) registered for path 'dtc' Submodule 'roms/QemuMacDrivers' (https://git.qemu.org/git/QemuMacDrivers.git) registered for path 'roms/QemuMacDrivers' Submodule 'roms/SLOF' (https://git.qemu.org/git/SLOF.git) registered for path 'roms/SLOF' Submodule 'roms/edk2' (https://git.qemu.org/git/edk2.git) registered for path 'roms/edk2' Submodule 'roms/ipxe' (https://git.qemu.org/git/ipxe.git) registered for path 'roms/ipxe' Submodule 'roms/openbios' (https://git.qemu.org/git/openbios.git) registered for path 'roms/openbios' Submodule 'roms/openhackware' (https://git.qemu.org/git/openhackware.git) registered for path 'roms/openhackware' Submodule 'roms/opensbi' (https://git.qemu.org/git/opensbi.git) registered for path 'roms/opensbi' Submodule 'roms/qemu-palcode' (https://git.qemu.org/git/qemu-palcode.git) registered for path 'roms/qemu-palcode' Submodule 'roms/seabios' (https://git.qemu.org/git/seabios.git/) registered for path 'roms/seabios' Submodule 'roms/seabios-hppa' (https://git.qemu.org/git/seabios-hppa.git) registered for path 'roms/seabios-hppa' Submodule 'roms/sgabios' (https://git.qemu.org/git/sgabios.git) registered for path 'roms/sgabios' Submodule 'roms/skiboot' (https://git.qemu.org/git/skiboot.git) registered for path 'roms/skiboot' Submodule 'roms/u-boot' (https://git.qemu.org/git/u-boot.git) registered for path 'roms/u-boot' Submodule 'roms/u-boot-sam460ex' (https://git.qemu.org/git/u-boot-sam460ex.git) registered for path 'roms/u-boot-sam460ex' Submodule 'slirp' (https://git.qemu.org/git/libslirp.git) registered for path 'slirp' Submodule 'tests/fp/berkeley-softfloat-3' (https://git.qemu.org/git/berkeley-softfloat-3.git) registered for path 'tests/fp/berkeley-softfloat-3' Submodule 'tests/fp/berkeley-testfloat-3' (https://git.qemu.org/git/berkeley-testfloat-3.git) registered for path 'tests/fp/berkeley-testfloat-3' Submodule 'ui/keycodemapdb' (https://git.qemu.org/git/keycodemapdb.git) registered for path 'ui/keycodemapdb' Cloning into 'capstone'... Submodule path 'capstone': checked out '22ead3e0bfdb87516656453336160e0a37b066bf' Cloning into 'dtc'... Submodule path 'dtc': checked out '88f18909db731a627456f26d779445f84e449536' Cloning into 'roms/QemuMacDrivers'... Submodule path 'roms/QemuMacDrivers': checked out '90c488d5f4a407342247b9ea869df1c2d9c8e266' Cloning into 'roms/SLOF'... Submodule path 'roms/SLOF': checked out 'ba1ab360eebe6338bb8d7d83a9220ccf7e213af3' Cloning into 'roms/edk2'... Submodule path 'roms/edk2': checked out '20d2e5a125e34fc8501026613a71549b2a1a3e54' Submodule 'SoftFloat' (https://github.com/ucb-bar/berkeley-softfloat-3.git) registered for path 'ArmPkg/Library/ArmSoftFloatLib/berkeley-softfloat-3' Submodule 'CryptoPkg/Library/OpensslLib/openssl' (https://github.com/openssl/openssl) registered for path 'CryptoPkg/Library/OpensslLib/openssl' Cloning into 'ArmPkg/Library/ArmSoftFloatLib/berkeley-softfloat-3'... Submodule path 'roms/edk2/ArmPkg/Library/ArmSoftFloatLib/berkeley-softfloat-3': checked out 'b64af41c3276f97f0e181920400ee056b9c88037' Cloning into 'CryptoPkg/Library/OpensslLib/openssl'... Submodule path 'roms/edk2/CryptoPkg/Library/OpensslLib/openssl': checked out '50eaac9f3337667259de725451f201e784599687' Submodule 'boringssl' (https://boringssl.googlesource.com/boringssl) registered for path 'boringssl' Submodule 'krb5' (https://github.com/krb5/krb5) registered for path 'krb5' Submodule 'pyca.cryptography' (https://github.com/pyca/cryptography.git) registered for path 'pyca-cryptography' Cloning into 'boringssl'... Submodule path 'roms/edk2/CryptoPkg/Library/OpensslLib/openssl/boringssl': checked out '2070f8ad9151dc8f3a73bffaa146b5e6937a583f' Cloning into 'krb5'... Submodule path 'roms/edk2/CryptoPkg/Library/OpensslLib/openssl/krb5': checked out 'b9ad6c49505c96a088326b62a52568e3484f2168' Cloning into 'pyca-cryptography'... Submodule path 'roms/edk2/CryptoPkg/Library/OpensslLib/openssl/pyca-cryptography': checked out '09403100de2f6f1cdd0d484dcb8e620f1c335c8f' Cloning into 'roms/ipxe'... Submodule path 'roms/ipxe': checked out 'de4565cbe76ea9f7913a01f331be3ee901bb6e17' Cloning into 'roms/openbios'... Submodule path 'roms/openbios': checked out 'c79e0ecb84f4f1ee3f73f521622e264edd1bf174' Cloning into 'roms/openhackware'... Submodule path 'roms/openhackware': checked out 'c559da7c8eec5e45ef1f67978827af6f0b9546f5' Cloning into 'roms/opensbi'... Submodule path 'roms/opensbi': checked out 'ce228ee0919deb9957192d723eecc8aaae2697c6' Cloning into 'roms/qemu-palcode'... Submodule path 'roms/qemu-palcode': checked out 'bf0e13698872450164fa7040da36a95d2d4b326f' Cloning into 'roms/seabios'... Submodule path 'roms/seabios': checked out 'a5cab58e9a3fb6e168aba919c5669bea406573b4' Cloning into 'roms/seabios-hppa'... Submodule path 'roms/seabios-hppa': checked out '0f4fe84658165e96ce35870fd19fc634e182e77b' Cloning into 'roms/sgabios'... Submodule path 'roms/sgabios': checked out 'cbaee52287e5f32373181cff50a00b6c4ac9015a' Cloning into 'roms/skiboot'... Submodule path 'roms/skiboot': checked out '261ca8e779e5138869a45f174caa49be6a274501' Cloning into 'roms/u-boot'... Submodule path 'roms/u-boot': checked out 'd3689267f92c5956e09cc7d1baa4700141662bff' Cloning into 'roms/u-boot-sam460ex'... Submodule path 'roms/u-boot-sam460ex': checked out '60b3916f33e617a815973c5a6df77055b2e3a588' Cloning into 'slirp'... Submodule path 'slirp': checked out '126c04acbabd7ad32c2b018fe10dfac2a3bc1210' Cloning into 'tests/fp/berkeley-softfloat-3'... Submodule path 'tests/fp/berkeley-softfloat-3': checked out 'b64af41c3276f97f0e181920400ee056b9c88037' Cloning into 'tests/fp/berkeley-testfloat-3'... Submodule path 'tests/fp/berkeley-testfloat-3': checked out '5a59dcec19327396a011a17fd924aed4fec416b3' Cloning into 'ui/keycodemapdb'... Submodule path 'ui/keycodemapdb': checked out '6b3d716e2b6472eb7189d3220552280ef3d832ce' Switched to a new branch 'test' 6e270bf linux-user: Support gdb 'qOffsets' query for ELF === OUTPUT BEGIN === ERROR: Author email address is mangled by the mailing list #2: Author: Josh Kunz via Qemu-devel <qemu-devel@nongnu.org> total: 1 errors, 0 warnings, 8 lines checked Commit 6e270bf43044 (linux-user: Support gdb 'qOffsets' query for ELF) has style problems, please review. If any of these errors are false positives report them to the maintainer, see CHECKPATCH in MAINTAINERS. === OUTPUT END === Test command exited with code: 1 The full log is available at http://patchew.org/logs/20190816233422.16715-1-jkz@google.com/testing.checkpatch/?type=message. --- Email generated automatically by Patchew [https://patchew.org/]. Please send your feedback to patchew-devel@redhat.com
Le 17/08/2019 à 01:34, Josh Kunz via Qemu-devel a écrit : > This is needed to support debugging PIE ELF binaries running under QEMU > user mode. Currently, `code_offset` and `data_offset` remain unset for > all ELF binaries, so GDB is unable to correctly locate the position of > the binary's text and data. > > The fields `code_offset`, and `data_offset` were originally added way > back in 2006 to support debugging of bFMT executables (978efd6aac6), > and support was just never added for ELF. Since non-PIE binaries are > loaded at exactly the address specified in the binary, GDB does not need > to relocate any symbols, so the buggy behavior is not normally observed. > > Buglink: https://bugs.launchpad.net/qemu/+bug/1528239 > Signed-off-by: Josh Kunz <jkz@google.com> > --- > linux-user/elfload.c | 2 ++ > 1 file changed, 2 insertions(+) As it seems they are text and data segment offsets, why it's not based on info->start_code and info->start_data? Thanks, Laurent
The `Data` and `Code` flags in `qOffsets` are actually section offsets rather than segment offsets. GDB relocates the symbols in those sections relative to their location in the binary. So we have to use `load_bias`. See here for a more detailed description: https://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html#General-Query-Packets On Mon, Aug 26, 2019 at 1:29 AM Laurent Vivier <laurent@vivier.eu> wrote: > Le 17/08/2019 à 01:34, Josh Kunz via Qemu-devel a écrit : > > This is needed to support debugging PIE ELF binaries running under QEMU > > user mode. Currently, `code_offset` and `data_offset` remain unset for > > all ELF binaries, so GDB is unable to correctly locate the position of > > the binary's text and data. > > > > The fields `code_offset`, and `data_offset` were originally added way > > back in 2006 to support debugging of bFMT executables (978efd6aac6), > > and support was just never added for ELF. Since non-PIE binaries are > > loaded at exactly the address specified in the binary, GDB does not need > > to relocate any symbols, so the buggy behavior is not normally observed. > > > > Buglink: https://bugs.launchpad.net/qemu/+bug/1528239 > > Signed-off-by: Josh Kunz <jkz@google.com> > > --- > > linux-user/elfload.c | 2 ++ > > 1 file changed, 2 insertions(+) > > As it seems they are text and data segment offsets, why it's not based > on info->start_code and info->start_data? > > Thanks, > Laurent >
Le 03/09/2019 à 21:19, Josh Kunz a écrit : > The `Data` and `Code` flags in `qOffsets` are actually section offsets > rather than segment offsets. GDB relocates the symbols in those sections > relative to their location in the binary. So we have to use `load_bias`. > > See here for a more detailed > description: https://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html#General-Query-Packets > Thank you for the details. Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Cc'ing Alex. On 9/3/19 9:19 PM, Josh Kunz via Qemu-devel wrote: > The `Data` and `Code` flags in `qOffsets` are actually section offsets > rather than segment offsets. GDB relocates the symbols in those sections > relative to their location in the binary. So we have to use `load_bias`. > > See here for a more detailed description: > https://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html#General-Query-Packets Maybe we can amend a reference to http://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html#index-qOffsets-packet in the commit. Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > On Mon, Aug 26, 2019 at 1:29 AM Laurent Vivier <laurent@vivier.eu> wrote: > >> Le 17/08/2019 à 01:34, Josh Kunz via Qemu-devel a écrit : >>> This is needed to support debugging PIE ELF binaries running under QEMU >>> user mode. Currently, `code_offset` and `data_offset` remain unset for >>> all ELF binaries, so GDB is unable to correctly locate the position of >>> the binary's text and data. >>> >>> The fields `code_offset`, and `data_offset` were originally added way >>> back in 2006 to support debugging of bFMT executables (978efd6aac6), >>> and support was just never added for ELF. Since non-PIE binaries are >>> loaded at exactly the address specified in the binary, GDB does not need >>> to relocate any symbols, so the buggy behavior is not normally observed. >>> >>> Buglink: https://bugs.launchpad.net/qemu/+bug/1528239 >>> Signed-off-by: Josh Kunz <jkz@google.com> >>> --- >>> linux-user/elfload.c | 2 ++ >>> 1 file changed, 2 insertions(+) >> >> As it seems they are text and data segment offsets, why it's not based >> on info->start_code and info->start_data? >> >> Thanks, >> Laurent >>
Le 17/08/2019 à 01:34, Josh Kunz via Qemu-devel a écrit : > This is needed to support debugging PIE ELF binaries running under QEMU > user mode. Currently, `code_offset` and `data_offset` remain unset for > all ELF binaries, so GDB is unable to correctly locate the position of > the binary's text and data. > > The fields `code_offset`, and `data_offset` were originally added way > back in 2006 to support debugging of bFMT executables (978efd6aac6), > and support was just never added for ELF. Since non-PIE binaries are > loaded at exactly the address specified in the binary, GDB does not need > to relocate any symbols, so the buggy behavior is not normally observed. > > Buglink: https://bugs.launchpad.net/qemu/+bug/1528239 > Signed-off-by: Josh Kunz <jkz@google.com> > --- > linux-user/elfload.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/linux-user/elfload.c b/linux-user/elfload.c > index 3365e192eb..ceac035208 100644 > --- a/linux-user/elfload.c > +++ b/linux-user/elfload.c > @@ -2380,6 +2380,8 @@ static void load_elf_image(const char *image_name, int image_fd, > } > > info->load_bias = load_bias; > + info->code_offset = load_bias; > + info->data_offset = load_bias; > info->load_addr = load_addr; > info->entry = ehdr->e_entry + load_bias; > info->start_code = -1; > Applied to my linux-user branch. Thanks, Laurent
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 3365e192eb..ceac035208 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2380,6 +2380,8 @@ static void load_elf_image(const char *image_name, int image_fd, } info->load_bias = load_bias; + info->code_offset = load_bias; + info->data_offset = load_bias; info->load_addr = load_addr; info->entry = ehdr->e_entry + load_bias; info->start_code = -1;
This is needed to support debugging PIE ELF binaries running under QEMU user mode. Currently, `code_offset` and `data_offset` remain unset for all ELF binaries, so GDB is unable to correctly locate the position of the binary's text and data. The fields `code_offset`, and `data_offset` were originally added way back in 2006 to support debugging of bFMT executables (978efd6aac6), and support was just never added for ELF. Since non-PIE binaries are loaded at exactly the address specified in the binary, GDB does not need to relocate any symbols, so the buggy behavior is not normally observed. Buglink: https://bugs.launchpad.net/qemu/+bug/1528239 Signed-off-by: Josh Kunz <jkz@google.com> --- linux-user/elfload.c | 2 ++ 1 file changed, 2 insertions(+)