f54c85e045
This patch decouples the kernel-specific implementation of the dynamic linker from its kernel-agnostic binary interface. The name of the kernel-specific dynamic linker binary now corresponds to the kernel, e.g., 'ld-linux.lib.so' or 'ld-nova.lib.so'. Applications are no longer linked directly against a concrete instance of the dynamic linker but against a shallow stub called 'ld.lib.so'. This stub contains nothing but the symbols provided by the dynamic linker. It thereby represents the Genode ABI. At system-integration time, the kernel-specific run/boot_dir back ends integrate the matching the kernel-specific variant of the dynamic linker as 'ld.lib.so' into the boot image. The ABI symbol file for the dynamic linker is located at 'base/lib/symbols/ld'. It contains the joint ABI of all supported architectures. The new utility 'tool/abi_symbols' eases the creation of such an ABI symbol file for a given shared library. Its result should be manually inspected and edited as needed. The patch removes the 'syscall' library from 'base_libs.mk' to avoid polluting the kernel-agnostic ABI with kernel-specific interfaces. Issue #2190 Issue #2195
99 lines
2.7 KiB
Tcl
Executable File
99 lines
2.7 KiB
Tcl
Executable File
#!/usr/bin/tclsh
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#
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# \brief Generate ABI symbol list for a shared library
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# \author Norman Feske
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# \date 2016-12-07
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#
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# The tool takes the shared library as argument and writes the output to
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# standard output. Each line of the resulting output contains the symbol name,
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# type, and size
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#
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# obtain symbol information via 'nm'
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set symbols [exec nm --format posix --dynamic $argv]
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# obtain demangled input via c++filt
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set demangled [exec c++filt << $symbols]
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set demangled_lines [split $demangled "\n"]
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set i 0
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set output_lines {}
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foreach line [split $symbols "\n"] {
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set size_hex 0
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set type "U"
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# match undefined symbol
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regexp {^(\w+) U\s*$} $line dummy name
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# match defined symbol, which does not always feature a size value
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regexp {^(\w+) (\w) \w+ ?(\w*)$} $line dummy name type size_hex
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# decimal symbol size
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set size_dec [expr 0x0$size_hex]
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set demangled_name $name
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regexp {^(.+) \w \w+( \w+)?$} [lindex $demangled_lines $i] dummy demangled_name
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set keep 1
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#
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# Ignore undefined symbols
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#
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if {$type == "U"} { set keep 0 }
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#
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# Check if the unmangled line contains a template-argument delimiter ('<')
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# prior the first opening parenthesis. This way, template methods match but
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# signatures of non-template functions/methods that take templated
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# arguments won't. We can discard symbols for the former but not the
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# latter.
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#
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if {[regexp {^[^(]+<} $demangled_name dummy]} { set keep 0 }
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#
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# Drop weak vtable and typeinfo symbols
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#
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# Those symbols are solely used to merge vtables between the executable and
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# shared library. When linking object files that use the same types, the
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# merging saves a lot space. However, the benefit at the coarse granularity
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# of shared libraries is rather small compared to the huge inflation of the
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# ABI size caused by such symbols.
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#
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if {($type == "V") && ([regexp {^(typeinfo |vtable )} $demangled_name dummy])} {
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set keep 0 }
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#
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# Drop weak C++ symbols
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#
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# In contrast to weak C symbols, which are rarely and always deliberately
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# created, weak C++ symbols are implicitly created by the compiler for
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# inline functions.
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#
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if {[regexp {W|V} $type] && ($name != $demangled_name)} {
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set keep 0 }
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# write result
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if {$keep} {
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#
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# Annotate the size for global data symbols where the size is needed to
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# create copy relations (ARM EABI) in the binary that is linked against
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# the shared library. For each global read-only data symbol found in
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# the shared object, the linker reserves space (according to the
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# symbol's size) in the binary's BSS segment. At runtime, the dynamic
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# linker copies the data from the shared library's symbol into the
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# binary's BSS.
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#
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if {$type == "D"} {
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puts "$name $type $size_dec"
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} else {
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puts "$name $type"
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}
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}
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incr i
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}
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