| Message ID | 20181025172057.20414-42-cota@braap.org |
|---|---|
| State | New |
| Headers | show |
| Series | Plugin support | expand |
Emilio G. Cota <cota@braap.org> writes: > For now only add it for ELF platforms, since we rely on the linker's > --dynamic-list flag to pass a list of symbols to be exported to the > executable. An alternative would be to use -rdynamic, but that would > expose all of QEMU's objects to plugins. > > I have no experience with non-ELF systems but I suspect adding support > for those should be pretty easy. > > Signed-off-by: Emilio G. Cota <cota@braap.org> As far as the configure logic is concerned: Reviewed-by: Alex Bennée <alex.bennee@linaro.org> I'm not quite following what is so special about the dynamic-list symbols compared to the rest of the symbols in the binary. when I do readelf -s they are all specified as GLOBAL DEFAULT. Perhaps this will become clearer to me once I get to the implementation of the plugins later in the series? > --- > configure | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 51 insertions(+) > > diff --git a/configure b/configure > index 03bf719ca7..78e86098e5 100755 > --- a/configure > +++ b/configure > @@ -30,6 +30,7 @@ TMPO="${TMPDIR1}/${TMPB}.o" > TMPCXX="${TMPDIR1}/${TMPB}.cxx" > TMPE="${TMPDIR1}/${TMPB}.exe" > TMPMO="${TMPDIR1}/${TMPB}.mo" > +TMPTXT="${TMPDIR1}/${TMPB}.txt" > > rm -f config.log > > @@ -477,6 +478,7 @@ libxml2="" > docker="no" > debug_mutex="no" > libpmem="" > +plugins="no" > > # cross compilers defaults, can be overridden with --cross-cc-ARCH > cross_cc_aarch64="aarch64-linux-gnu-gcc" > @@ -1443,6 +1445,10 @@ for opt do > ;; > --disable-libpmem) libpmem=no > ;; > + --enable-plugins) plugins="yes" > + ;; > + --disable-plugins) plugins="no" > + ;; > *) > echo "ERROR: unknown option $opt" > echo "Try '$0 --help' for more information" > @@ -1633,6 +1639,8 @@ Advanced options (experts only): > xen pv domain builder > --enable-debug-stack-usage > track the maximum stack usage of stacks created by qemu_alloc_stack > + --enable-plugins > + enable plugins via shared library loading > > Optional features, enabled with --enable-FEATURE and > disabled with --disable-FEATURE, default is enabled if available: > @@ -5204,6 +5212,42 @@ if compile_prog "" "" ; then > atomic64=yes > fi > > +######################################### > +# See if --dynamic-list is supported by the linker > + > +cat > $TMPTXT <<EOF > +{ > + foo; > +}; > +EOF > + > +cat > $TMPC <<EOF > +#include <stdio.h> > +void foo(void); > + > +void foo(void) > +{ > + printf("foo\n"); > +} > + > +int main(void) > +{ > + foo(); > + return 0; > +} > +EOF > + > +if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then > + ld_dynamic_list="yes" > +else > + if test "$plugins" = "yes" ; then > + error_exit \ > + "Plugin support requires specifying a set of symbols that " \ > + "are exported to plugins. Unfortunately your linker doesn't " \ > + "support the flag (--dynamic-list) used for this purpose." > + fi > +fi > + > ######################################## > # See if 16-byte vector operations are supported. > # Even without a vector unit the compiler may expand these. > @@ -6091,6 +6135,7 @@ echo "VxHS block device $vxhs" > echo "capstone $capstone" > echo "docker $docker" > echo "libpmem support $libpmem" > +echo "plugin support $plugins" > > if test "$sdl_too_old" = "yes"; then > echo "-> Your SDL version is too old - please upgrade to have SDL support" > @@ -6849,6 +6894,12 @@ if test "$libpmem" = "yes" ; then > echo "CONFIG_LIBPMEM=y" >> $config_host_mak > fi > > +if test "$plugins" = "yes" ; then > + echo "CONFIG_PLUGINS=y" >> $config_host_mak > + LIBS="-ldl $LIBS" > + LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" > +fi > + > if test "$tcg_interpreter" = "yes"; then > QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/tci $QEMU_INCLUDES" > elif test "$ARCH" = "sparc64" ; then -- Alex Bennée
On Thu, Oct 25, 2018 at 01:20:50PM -0400, Emilio G. Cota wrote: > For now only add it for ELF platforms, since we rely on the linker's > --dynamic-list flag to pass a list of symbols to be exported to the > executable. An alternative would be to use -rdynamic, but that would > expose all of QEMU's objects to plugins. > > I have no experience with non-ELF systems but I suspect adding support > for those should be pretty easy. > > Signed-off-by: Emilio G. Cota <cota@braap.org> > --- > configure | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 51 insertions(+) > > diff --git a/configure b/configure > index 03bf719ca7..78e86098e5 100755 > --- a/configure > +++ b/configure > @@ -30,6 +30,7 @@ TMPO="${TMPDIR1}/${TMPB}.o" > TMPCXX="${TMPDIR1}/${TMPB}.cxx" > TMPE="${TMPDIR1}/${TMPB}.exe" > TMPMO="${TMPDIR1}/${TMPB}.mo" > +TMPTXT="${TMPDIR1}/${TMPB}.txt" > > rm -f config.log > > @@ -477,6 +478,7 @@ libxml2="" > docker="no" > debug_mutex="no" > libpmem="" > +plugins="no" > > # cross compilers defaults, can be overridden with --cross-cc-ARCH > cross_cc_aarch64="aarch64-linux-gnu-gcc" > @@ -1443,6 +1445,10 @@ for opt do > ;; > --disable-libpmem) libpmem=no > ;; > + --enable-plugins) plugins="yes" > + ;; > + --disable-plugins) plugins="no" > + ;; > *) > echo "ERROR: unknown option $opt" > echo "Try '$0 --help' for more information" > @@ -1633,6 +1639,8 @@ Advanced options (experts only): > xen pv domain builder > --enable-debug-stack-usage > track the maximum stack usage of stacks created by qemu_alloc_stack > + --enable-plugins > + enable plugins via shared library loading > > Optional features, enabled with --enable-FEATURE and > disabled with --disable-FEATURE, default is enabled if available: > @@ -5204,6 +5212,42 @@ if compile_prog "" "" ; then > atomic64=yes > fi > > +######################################### > +# See if --dynamic-list is supported by the linker > + > +cat > $TMPTXT <<EOF > +{ > + foo; > +}; > +EOF > + > +cat > $TMPC <<EOF > +#include <stdio.h> > +void foo(void); > + > +void foo(void) > +{ > + printf("foo\n"); > +} > + > +int main(void) > +{ > + foo(); > + return 0; > +} > +EOF > + > +if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then > + ld_dynamic_list="yes" > +else > + if test "$plugins" = "yes" ; then > + error_exit \ > + "Plugin support requires specifying a set of symbols that " \ > + "are exported to plugins. Unfortunately your linker doesn't " \ > + "support the flag (--dynamic-list) used for this purpose." > + fi > +fi > + > ######################################## > # See if 16-byte vector operations are supported. > # Even without a vector unit the compiler may expand these. > @@ -6091,6 +6135,7 @@ echo "VxHS block device $vxhs" > echo "capstone $capstone" > echo "docker $docker" > echo "libpmem support $libpmem" > +echo "plugin support $plugins" > > if test "$sdl_too_old" = "yes"; then > echo "-> Your SDL version is too old - please upgrade to have SDL support" > @@ -6849,6 +6894,12 @@ if test "$libpmem" = "yes" ; then > echo "CONFIG_LIBPMEM=y" >> $config_host_mak > fi > > +if test "$plugins" = "yes" ; then > + echo "CONFIG_PLUGINS=y" >> $config_host_mak > + LIBS="-ldl $LIBS" > + LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" > +fi > + > if test "$tcg_interpreter" = "yes"; then > QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/tci $QEMU_INCLUDES" > elif test "$ARCH" = "sparc64" ; then > -- > 2.17.1 > > ld64 on macOS has similar -exported_symbols_list option. Here's the reference: -exported_symbols_list filename The specified filename contains a list of global symbol names that will remain as global symbols in the output file. All other global symbols will be treated as if they were marked as __private_extern__ (aka visibility=hidden) and will not be global in the output file. The symbol names listed in filename must be one per line. Leading and trailing white space are not part of the symbol name. Lines starting with # are ignored, as are lines with only white space. Some wildcards (similar to shell file matching) are supported. The * matches zero or more characters. The ? matches one character. [abc] matches one character which must be an 'a', 'b', or 'c'. [a-z] matches any single lower case letter from 'a' to 'z'. I can try your branch if you add support of the linker flag or send required changes via GitHub. Best regards, Roman
On Tue, Nov 27, 2018 at 12:11:32 +0000, Alex Bennée wrote: > > Emilio G. Cota <cota@braap.org> writes: > > > For now only add it for ELF platforms, since we rely on the linker's > > --dynamic-list flag to pass a list of symbols to be exported to the > > executable. An alternative would be to use -rdynamic, but that would > > expose all of QEMU's objects to plugins. > > > > I have no experience with non-ELF systems but I suspect adding support > > for those should be pretty easy. > > > > Signed-off-by: Emilio G. Cota <cota@braap.org> > > As far as the configure logic is concerned: > > Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > > I'm not quite following what is so special about the dynamic-list > symbols compared to the rest of the symbols in the binary. when I do > readelf -s they are all specified as GLOBAL DEFAULT. > > Perhaps this will become clearer to me once I get to the implementation > of the plugins later in the series? You should look at `readelf --dyn-syms's output. There you'll see that the only defined function symbols are qemu_plugin_* ones (plus _init and _fini). The goal is to prevent plugins from accessing symbols outside of the plugin API. For instance, if from plugin 'foo' I try to call qht_init (after having added the necessary declarations in foo.c), at dlopen time I get: plugin_load: libfoo.so: undefined symbol: qht_init The alternative is to export all symbols; we can do this by passing --export-dynamic to the linker instead of an explicit --dynamic-list. We can then access *any* global symbol in the QEMU executable. The previous example now works past dlopen, i.e. I can call qht_init from my plugin: ERROR:/data/src/qemu/util/qht.c:401:qht_init: assertion failed: (cmp) Thanks, Emilio
On Tue, Nov 27, 2018 at 15:43:52 +0300, Roman Bolshakov wrote: > ld64 on macOS has similar -exported_symbols_list option. Here's the reference: > > -exported_symbols_list filename > The specified filename contains a list of global symbol names > that will remain as global symbols in the output file. All other > global symbols will be treated as if they were marked as > __private_extern__ (aka visibility=hidden) and will not be global in > the output file. The symbol names listed in filename must be one per > line. Leading and trailing white space are not part of the symbol > name. Lines starting with # are ignored, as are lines with only white > space. Some wildcards (similar to shell file matching) are supported. > The * matches zero or more characters. The ? matches one character. > [abc] matches one character which must be an 'a', 'b', or 'c'. > [a-z] matches any single lower case letter from 'a' to 'z'. > > > I can try your branch if you add support of the linker flag or send required > changes via GitHub. Can you please try this branch? I added a commit with the appended. https://github.com/cota/qemu/tree/plugin-v2 You can inspect the symbols in the final binary with `readelf --dyn-syms' or `nm -D'. Thanks, Emilio --- diff --git a/configure b/configure index fe9707d951..3dc9c9697b 100755 --- a/configure +++ b/configure @@ -5176,15 +5176,31 @@ int main(void) } EOF +ld_dynamic_list="no" if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then ld_dynamic_list="yes" -else - if test "$plugins" = "yes" ; then - error_exit \ - "Plugin support requires specifying a set of symbols that " \ - "are exported to plugins. Unfortunately your linker doesn't " \ - "support the flag (--dynamic-list) used for this purpose." - fi +fi + +######################################### +# See if -exported_symbols_list is supported by the linker + +cat > $TMPTXT <<EOF + foo +EOF + +ld_exported_symbols_list="no" +if compile_prog "" "-Wl,-exported_symbols_list,$TMPTXT" ; then + ld_exported_symbols_list="yes" +fi + +if test "$plugins" = "yes" && + test "$ld_dynamic_list" = "no" && + test "$ld_exported_symbols_list" = "no" ; then + error_exit \ + "Plugin support requires specifying a set of symbols that " \ + "are exported to plugins. Unfortunately your linker doesn't " \ + "support the flag (--dynamic-list or -exported_symbols_list) used " \ + "for this purpose." fi ######################################## @@ -6827,7 +6843,18 @@ fi if test "$plugins" = "yes" ; then echo "CONFIG_PLUGINS=y" >> $config_host_mak LIBS="-ldl $LIBS" - LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" + if test "$ld_dynamic_list" = "yes" ; then + LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" + elif test "$ld_exported_symbols_list" = "yes" ; then + ld64_symbols=qemu-plugins-ld64.symbols + echo "# Automatically generated by configure - do not modify" > $ld64_symbols + cat "$source_path/qemu-plugins.symbols" | grep qemu_ | sed 's/;//g' >> $ld64_symbols + LDFLAGS="-Wl,-exported_symbols_list,\$(BUILD_DIR)/$ld64_symbols $LDFLAGS" + else + error_exit \ + "If \$plugins=yes, either \$ld_dynamic_list or " \ + "\$ld_exported_symbols_list should have been set to 'yes'." + fi fi if test "$tcg_interpreter" = "yes"; then
On Tue, Nov 27, 2018 at 06:13:57PM -0500, Emilio G. Cota wrote: > On Tue, Nov 27, 2018 at 15:43:52 +0300, Roman Bolshakov wrote: > > ld64 on macOS has similar -exported_symbols_list option. Here's the reference: > > > > -exported_symbols_list filename > > The specified filename contains a list of global symbol names > > that will remain as global symbols in the output file. All other > > global symbols will be treated as if they were marked as > > __private_extern__ (aka visibility=hidden) and will not be global in > > the output file. The symbol names listed in filename must be one per > > line. Leading and trailing white space are not part of the symbol > > name. Lines starting with # are ignored, as are lines with only white > > space. Some wildcards (similar to shell file matching) are supported. > > The * matches zero or more characters. The ? matches one character. > > [abc] matches one character which must be an 'a', 'b', or 'c'. > > [a-z] matches any single lower case letter from 'a' to 'z'. > > > > > > I can try your branch if you add support of the linker flag or send required > > changes via GitHub. > > Can you please try this branch? I added a commit with the appended. > https://github.com/cota/qemu/tree/plugin-v2 > > You can inspect the symbols in the final binary with > `readelf --dyn-syms' or `nm -D'. > > Thanks, > > Emilio > > --- > diff --git a/configure b/configure > index fe9707d951..3dc9c9697b 100755 > --- a/configure > +++ b/configure > @@ -5176,15 +5176,31 @@ int main(void) > } > EOF > > +ld_dynamic_list="no" > if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then > ld_dynamic_list="yes" > -else > - if test "$plugins" = "yes" ; then > - error_exit \ > - "Plugin support requires specifying a set of symbols that " \ > - "are exported to plugins. Unfortunately your linker doesn't " \ > - "support the flag (--dynamic-list) used for this purpose." > - fi > +fi > + > +######################################### > +# See if -exported_symbols_list is supported by the linker > + > +cat > $TMPTXT <<EOF > + foo > +EOF > + > +ld_exported_symbols_list="no" > +if compile_prog "" "-Wl,-exported_symbols_list,$TMPTXT" ; then > + ld_exported_symbols_list="yes" > +fi > + > +if test "$plugins" = "yes" && > + test "$ld_dynamic_list" = "no" && > + test "$ld_exported_symbols_list" = "no" ; then > + error_exit \ > + "Plugin support requires specifying a set of symbols that " \ > + "are exported to plugins. Unfortunately your linker doesn't " \ > + "support the flag (--dynamic-list or -exported_symbols_list) used " \ > + "for this purpose." > fi > > ######################################## > @@ -6827,7 +6843,18 @@ fi > if test "$plugins" = "yes" ; then > echo "CONFIG_PLUGINS=y" >> $config_host_mak > LIBS="-ldl $LIBS" > - LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" > + if test "$ld_dynamic_list" = "yes" ; then > + LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" > + elif test "$ld_exported_symbols_list" = "yes" ; then > + ld64_symbols=qemu-plugins-ld64.symbols > + echo "# Automatically generated by configure - do not modify" > $ld64_symbols > + cat "$source_path/qemu-plugins.symbols" | grep qemu_ | sed 's/;//g' >> $ld64_symbols > + LDFLAGS="-Wl,-exported_symbols_list,\$(BUILD_DIR)/$ld64_symbols $LDFLAGS" > + else > + error_exit \ > + "If \$plugins=yes, either \$ld_dynamic_list or " \ > + "\$ld_exported_symbols_list should have been set to 'yes'." > + fi > fi > > if test "$tcg_interpreter" = "yes"; then > Hi Emilio, The test of -exported_symbols_list fails: Undefined symbols for architecture x86_64: "foo", referenced from: -exported_symbol[s_list] command line option (maybe you meant: _foo) All functions on macOS are prefixed with underscore [1]: "The name of a symbol representing a function that conforms to standard C calling conventions is the name of the function with an underscore prefix. Thus, the name of the symbol representing the function main would be _main." So it can be fixed by prepending foo and qemu-plugins-ld64.symbols with underscore: diff --git a/configure b/configure index 3dc9c9697b..85dd15732c 100755 --- a/configure +++ b/configure @@ -5185,7 +5185,7 @@ fi # See if -exported_symbols_list is supported by the linker cat > $TMPTXT <<EOF - foo + _foo EOF ld_exported_symbols_list="no" @@ -6848,7 +6848,7 @@ if test "$plugins" = "yes" ; then elif test "$ld_exported_symbols_list" = "yes" ; then ld64_symbols=qemu-plugins-ld64.symbols echo "# Automatically generated by configure - do not modify" > $ld64_symbols - cat "$source_path/qemu-plugins.symbols" | grep qemu_ | sed 's/;//g' >> $ld64_symbols + cat "$source_path/qemu-plugins.symbols" | sed -nE 's/^([[:space:]]+)(.+);/\1_\2/p' >> $ld64_symbols LDFLAGS="-Wl,-exported_symbols_list,\$(BUILD_DIR)/$ld64_symbols $LDFLAGS" else error_exit \ -- Then if I print globally defined functions I can see it in config-temp/qemu-conf.exe: nm -g -U config-temp/qemu-conf.exe 0000000100000f50 T _foo qemu-ga fails to link because it doesn't have symbols declared in qemu-plugins-ld64.symbols. Perhaps "-Wl,-exported_symbols_list" should be applied only to qemu-system? [1] https://developer.apple.com/library/archive/documentation/DeveloperTools/Conceptual/MachOTopics/1-Articles/executing_files.html#//apple_ref/doc/uid/TP40001829-97182-TPXREF112 Best regards, Roman
On Wed, Nov 28, 2018 at 13:43:30 +0300, Roman Bolshakov wrote: > The test of -exported_symbols_list fails: > Undefined symbols for architecture x86_64: > "foo", referenced from: > -exported_symbol[s_list] command line option > (maybe you meant: _foo) > > All functions on macOS are prefixed with underscore [1]: > "The name of a symbol representing a function that conforms to standard C > calling conventions is the name of the function with an underscore prefix. > Thus, the name of the symbol representing the function main would be _main." > > So it can be fixed by prepending foo and qemu-plugins-ld64.symbols with > underscore: Ah I see, thanks! (snip) > qemu-ga fails to link because it doesn't have symbols declared in > qemu-plugins-ld64.symbols. Perhaps "-Wl,-exported_symbols_list" should > be applied only to qemu-system? I just pushed to the same github branch the appended fixup. The idea is to only add the linker flags when the output binary links plugin.o. Can you please test? Thanks, Emilio --- commit 8f45416b79765b66e5ce0fca7db93b97bbcfcfbb Author: Emilio G. Cota <cota@braap.org> Date: Wed Nov 28 12:11:23 2018 -0500 configure: ld64 fixup And copy the file to the build dir also for !ld64. Signed-off-by: Emilio G. Cota <cota@braap.org> diff --git a/Makefile.target b/Makefile.target index 719699696d..7ea17d71cb 100644 --- a/Makefile.target +++ b/Makefile.target @@ -107,7 +107,23 @@ obj-y += target/$(TARGET_BASE_ARCH)/ obj-y += disas.o obj-$(call notempty,$(TARGET_XML_FILES)) += gdbstub-xml.o -obj-$(CONFIG_PLUGINS) += plugin.o +ifdef CONFIG_PLUGINS +obj-y += plugin.o +# Abuse -libs suffix to only link with --dynamic-list/-exported_symbols_list +# when the final binary includes the plugin object. +# +# Note that simply setting LDFLAGS is not enough: we build binaries that +# never link plugin.o, and the linker might fail (at least ld64 does) +# if the symbols in the list are not in the output binary. + ifdef CONFIG_HAS_LD_DYNAMIC_LIST + plugin.o-libs := -Wl,--dynamic-list=$(BUILD_DIR)/qemu-plugins-ld.symbols + else + ifdef CONFIG_HAS_LD_EXPORTED_SYMBOLS_LIST + plugin.o-libs := \ + -Wl,-exported_symbols_list,$(BUILD_DIR)/qemu-plugins-ld64.symbols + endif + endif +endif ######################################################### # Linux user emulator target diff --git a/configure b/configure index 3dc9c9697b..395acf831e 100755 --- a/configure +++ b/configure @@ -5185,7 +5185,7 @@ fi # See if -exported_symbols_list is supported by the linker cat > $TMPTXT <<EOF - foo + _foo EOF ld_exported_symbols_list="no" @@ -6843,13 +6843,17 @@ fi if test "$plugins" = "yes" ; then echo "CONFIG_PLUGINS=y" >> $config_host_mak LIBS="-ldl $LIBS" + # Copy the export object list to the build dir if test "$ld_dynamic_list" = "yes" ; then - LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" + echo "CONFIG_HAS_LD_DYNAMIC_LIST=yes" >> $config_host_mak + ld_symbols=qemu-plugins-ld.symbols + cp "$source_path/qemu-plugins.symbols" $ld_symbols elif test "$ld_exported_symbols_list" = "yes" ; then + echo "CONFIG_HAS_LD_EXPORTED_SYMBOLS_LIST=yes" >> $config_host_mak ld64_symbols=qemu-plugins-ld64.symbols echo "# Automatically generated by configure - do not modify" > $ld64_symbols - cat "$source_path/qemu-plugins.symbols" | grep qemu_ | sed 's/;//g' >> $ld64_symbols - LDFLAGS="-Wl,-exported_symbols_list,\$(BUILD_DIR)/$ld64_symbols $LDFLAGS" + grep 'qemu_' "$source_path/qemu-plugins.symbols" | sed 's/;//g' | \ + sed -E 's/^\s*(.*)/_\1/' >> $ld64_symbols else error_exit \ "If \$plugins=yes, either \$ld_dynamic_list or " \
On Wed, Nov 28, 2018 at 12:23:32PM -0500, Emilio G. Cota wrote: > On Wed, Nov 28, 2018 at 13:43:30 +0300, Roman Bolshakov wrote: > > qemu-ga fails to link because it doesn't have symbols declared in > > qemu-plugins-ld64.symbols. Perhaps "-Wl,-exported_symbols_list" should > > be applied only to qemu-system? > > I just pushed to the same github branch the appended fixup. > The idea is to only add the linker flags when the output > binary links plugin.o. > > Can you please test? > > Thanks, > > Emilio > > --- > commit 8f45416b79765b66e5ce0fca7db93b97bbcfcfbb > Author: Emilio G. Cota <cota@braap.org> > Date: Wed Nov 28 12:11:23 2018 -0500 > > configure: ld64 fixup > > And copy the file to the build dir also for !ld64. > > Signed-off-by: Emilio G. Cota <cota@braap.org> > > diff --git a/Makefile.target b/Makefile.target > index 719699696d..7ea17d71cb 100644 > --- a/Makefile.target > +++ b/Makefile.target > @@ -107,7 +107,23 @@ obj-y += target/$(TARGET_BASE_ARCH)/ > obj-y += disas.o > obj-$(call notempty,$(TARGET_XML_FILES)) += gdbstub-xml.o > > -obj-$(CONFIG_PLUGINS) += plugin.o > +ifdef CONFIG_PLUGINS > +obj-y += plugin.o > +# Abuse -libs suffix to only link with --dynamic-list/-exported_symbols_list > +# when the final binary includes the plugin object. > +# > +# Note that simply setting LDFLAGS is not enough: we build binaries that > +# never link plugin.o, and the linker might fail (at least ld64 does) > +# if the symbols in the list are not in the output binary. > + ifdef CONFIG_HAS_LD_DYNAMIC_LIST > + plugin.o-libs := -Wl,--dynamic-list=$(BUILD_DIR)/qemu-plugins-ld.symbols > + else > + ifdef CONFIG_HAS_LD_EXPORTED_SYMBOLS_LIST > + plugin.o-libs := \ > + -Wl,-exported_symbols_list,$(BUILD_DIR)/qemu-plugins-ld64.symbols > + endif > + endif > +endif > > ######################################################### > # Linux user emulator target > diff --git a/configure b/configure > index 3dc9c9697b..395acf831e 100755 > --- a/configure > +++ b/configure > @@ -5185,7 +5185,7 @@ fi > # See if -exported_symbols_list is supported by the linker > > cat > $TMPTXT <<EOF > - foo > + _foo > EOF > > ld_exported_symbols_list="no" > @@ -6843,13 +6843,17 @@ fi > if test "$plugins" = "yes" ; then > echo "CONFIG_PLUGINS=y" >> $config_host_mak > LIBS="-ldl $LIBS" > + # Copy the export object list to the build dir > if test "$ld_dynamic_list" = "yes" ; then > - LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" > + echo "CONFIG_HAS_LD_DYNAMIC_LIST=yes" >> $config_host_mak > + ld_symbols=qemu-plugins-ld.symbols > + cp "$source_path/qemu-plugins.symbols" $ld_symbols > elif test "$ld_exported_symbols_list" = "yes" ; then > + echo "CONFIG_HAS_LD_EXPORTED_SYMBOLS_LIST=yes" >> $config_host_mak > ld64_symbols=qemu-plugins-ld64.symbols > echo "# Automatically generated by configure - do not modify" > $ld64_symbols > - cat "$source_path/qemu-plugins.symbols" | grep qemu_ | sed 's/;//g' >> $ld64_symbols > - LDFLAGS="-Wl,-exported_symbols_list,\$(BUILD_DIR)/$ld64_symbols $LDFLAGS" > + grep 'qemu_' "$source_path/qemu-plugins.symbols" | sed 's/;//g' | \ > + sed -E 's/^\s*(.*)/_\1/' >> $ld64_symbols > else > error_exit \ > "If \$plugins=yes, either \$ld_dynamic_list or " \ > Hi Emilio, I think there's an issue with "\s" character class, it's not recognized by macOS sed and I'm getting incorrect lines in qemu-plugins-ld64.symbols: _ qemu_xxx _ qemu_xyz After I replaced "\s" with "[[:space:]]", linking proceeds further, but doesn't succeed because of an unresolved reference for qemu-system cris, lm32, m68k, microblaze, microblazeel, moxie, nios2, or1k, riscv32, riscv64, sparc, unicore32, tricore, xtensa, xtensaeb: Undefined symbols for architecture x86_64: "_pci_register_bar", referenced from: _plugin_chan_realize in plugin-chan.o It probably has nothing to do with macOS per-se and shouldn't link on Linux as well. If I disable the aforementioned targets the build succeeds and I can see the symbols from qemu-plugins-ld64.symbols in compiled qemu-system binaries. Best regards, Roman
On Thu, Nov 29, 2018 at 12:57:16 +0300, Roman Bolshakov wrote: > Hi Emilio, > > I think there's an issue with "\s" character class, it's not recognized > by macOS sed and I'm getting incorrect lines in > qemu-plugins-ld64.symbols: > _ qemu_xxx > _ qemu_xyz > > After I replaced "\s" with "[[:space:]]", linking proceeds further Nice, thanks. Will update. > , but doesn't succeed because of an unresolved reference for qemu-system cris, > lm32, m68k, microblaze, microblazeel, moxie, nios2, or1k, riscv32, > riscv64, sparc, unicore32, tricore, xtensa, xtensaeb: > > Undefined symbols for architecture x86_64: > "_pci_register_bar", referenced from: > _plugin_chan_realize in plugin-chan.o > > It probably has nothing to do with macOS per-se and shouldn't link on > Linux as well. If I disable the aforementioned targets the build > succeeds and I can see the symbols from qemu-plugins-ld64.symbols in > compiled qemu-system binaries. Yes, that's because plugin-chan should only be built if the guest has PCI support. Will fix. Thanks, Emilio
On Thu, Nov 29, 2018 at 12:00:55 -0500, Emilio G. Cota wrote: > On Thu, Nov 29, 2018 at 12:57:16 +0300, Roman Bolshakov wrote: > > Hi Emilio, > > > > I think there's an issue with "\s" character class, it's not recognized > > by macOS sed and I'm getting incorrect lines in > > qemu-plugins-ld64.symbols: > > _ qemu_xxx > > _ qemu_xyz > > > > After I replaced "\s" with "[[:space:]]", linking proceeds further > > Nice, thanks. Will update. > > > , but doesn't succeed because of an unresolved reference for qemu-system cris, > > lm32, m68k, microblaze, microblazeel, moxie, nios2, or1k, riscv32, > > riscv64, sparc, unicore32, tricore, xtensa, xtensaeb: > > > > Undefined symbols for architecture x86_64: > > "_pci_register_bar", referenced from: > > _plugin_chan_realize in plugin-chan.o > > > > It probably has nothing to do with macOS per-se and shouldn't link on > > Linux as well. If I disable the aforementioned targets the build > > succeeds and I can see the symbols from qemu-plugins-ld64.symbols in > > compiled qemu-system binaries. > > Yes, that's because plugin-chan should only be built if the guest has PCI > support. Will fix. Pushed the fixes to the github branch. Hope it works for you now! Thanks, Emilio
On Thu, Nov 29, 2018 at 12:49:27PM -0500, Emilio G. Cota wrote: > On Thu, Nov 29, 2018 at 12:00:55 -0500, Emilio G. Cota wrote: > > On Thu, Nov 29, 2018 at 12:57:16 +0300, Roman Bolshakov wrote: > > > Hi Emilio, > > > > > > I think there's an issue with "\s" character class, it's not recognized > > > by macOS sed and I'm getting incorrect lines in > > > qemu-plugins-ld64.symbols: > > > _ qemu_xxx > > > _ qemu_xyz > > > > > > After I replaced "\s" with "[[:space:]]", linking proceeds further > > > > Nice, thanks. Will update. > > > > > , but doesn't succeed because of an unresolved reference for qemu-system cris, > > > lm32, m68k, microblaze, microblazeel, moxie, nios2, or1k, riscv32, > > > riscv64, sparc, unicore32, tricore, xtensa, xtensaeb: > > > > > > Undefined symbols for architecture x86_64: > > > "_pci_register_bar", referenced from: > > > _plugin_chan_realize in plugin-chan.o > > > > > > It probably has nothing to do with macOS per-se and shouldn't link on > > > Linux as well. If I disable the aforementioned targets the build > > > succeeds and I can see the symbols from qemu-plugins-ld64.symbols in > > > compiled qemu-system binaries. > > > > Yes, that's because plugin-chan should only be built if the guest has PCI > > support. Will fix. > > Pushed the fixes to the github branch. Hope it works for you now! > Thank you Emilio, the build succeded with the set of declared symbols exposed in qemu-system. I've just noticed qemu-plugins-ld64.symbols should be added to .gitignore. Best regards, Roman
diff --git a/configure b/configure index 03bf719ca7..78e86098e5 100755 --- a/configure +++ b/configure @@ -30,6 +30,7 @@ TMPO="${TMPDIR1}/${TMPB}.o" TMPCXX="${TMPDIR1}/${TMPB}.cxx" TMPE="${TMPDIR1}/${TMPB}.exe" TMPMO="${TMPDIR1}/${TMPB}.mo" +TMPTXT="${TMPDIR1}/${TMPB}.txt" rm -f config.log @@ -477,6 +478,7 @@ libxml2="" docker="no" debug_mutex="no" libpmem="" +plugins="no" # cross compilers defaults, can be overridden with --cross-cc-ARCH cross_cc_aarch64="aarch64-linux-gnu-gcc" @@ -1443,6 +1445,10 @@ for opt do ;; --disable-libpmem) libpmem=no ;; + --enable-plugins) plugins="yes" + ;; + --disable-plugins) plugins="no" + ;; *) echo "ERROR: unknown option $opt" echo "Try '$0 --help' for more information" @@ -1633,6 +1639,8 @@ Advanced options (experts only): xen pv domain builder --enable-debug-stack-usage track the maximum stack usage of stacks created by qemu_alloc_stack + --enable-plugins + enable plugins via shared library loading Optional features, enabled with --enable-FEATURE and disabled with --disable-FEATURE, default is enabled if available: @@ -5204,6 +5212,42 @@ if compile_prog "" "" ; then atomic64=yes fi +######################################### +# See if --dynamic-list is supported by the linker + +cat > $TMPTXT <<EOF +{ + foo; +}; +EOF + +cat > $TMPC <<EOF +#include <stdio.h> +void foo(void); + +void foo(void) +{ + printf("foo\n"); +} + +int main(void) +{ + foo(); + return 0; +} +EOF + +if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then + ld_dynamic_list="yes" +else + if test "$plugins" = "yes" ; then + error_exit \ + "Plugin support requires specifying a set of symbols that " \ + "are exported to plugins. Unfortunately your linker doesn't " \ + "support the flag (--dynamic-list) used for this purpose." + fi +fi + ######################################## # See if 16-byte vector operations are supported. # Even without a vector unit the compiler may expand these. @@ -6091,6 +6135,7 @@ echo "VxHS block device $vxhs" echo "capstone $capstone" echo "docker $docker" echo "libpmem support $libpmem" +echo "plugin support $plugins" if test "$sdl_too_old" = "yes"; then echo "-> Your SDL version is too old - please upgrade to have SDL support" @@ -6849,6 +6894,12 @@ if test "$libpmem" = "yes" ; then echo "CONFIG_LIBPMEM=y" >> $config_host_mak fi +if test "$plugins" = "yes" ; then + echo "CONFIG_PLUGINS=y" >> $config_host_mak + LIBS="-ldl $LIBS" + LDFLAGS="-Wl,--dynamic-list=\$(SRC_PATH)/qemu-plugins.symbols $LDFLAGS" +fi + if test "$tcg_interpreter" = "yes"; then QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/tci $QEMU_INCLUDES" elif test "$ARCH" = "sparc64" ; then
For now only add it for ELF platforms, since we rely on the linker's --dynamic-list flag to pass a list of symbols to be exported to the executable. An alternative would be to use -rdynamic, but that would expose all of QEMU's objects to plugins. I have no experience with non-ELF systems but I suspect adding support for those should be pretty easy. Signed-off-by: Emilio G. Cota <cota@braap.org> --- configure | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+)