https://sourceware.org/bugzilla/show_bug.cgi?id=23169
--- Comment #11 from Fangrui Song <i at maskray dot me> --- (In reply to H.J. Lu from comment #9) > (In reply to Fangrui Song from comment #8) > > Can https://sourceware.org/glibc/wiki/GNU_IFUNC to updated to document what > > is supported and what isn't supported? > > > > IFUNC documentation needs improvements. > > > > > Is the idea that > > (1) the main executable is relocated the last. > > (2) by making the main executable STT_GNU_IFUNC STT_FUNC, ifunc resolver > > will not be called while the main executable is unresolved > > Correct. > > > (3) How does an ifunc resolver defined in another DSO work? Let the user > > ensures DT_NEEDED BFS order or the ld.so itself does topological sorting? > > Current ld.so issues an error with a suggestion when it detects it. I currently cannot find a straightforward rule to explain the GNU ld behavior and what is supported in glibc. cat > ./a.s <<eof resolver: ret .globl ifunc, _start .type ifunc, @gnu_indirect_function .set ifunc, resolver _start: movq ifunc@GOTPCREL(%rip), %rax call ifunc eof echo 'call ifunc' > ./b.s gcc -shared -fpic b.s -o b.so ~/Dev/binutils-gdb/Debug/ld/ld-new is a top-of-tree ld. % ~/Dev/binutils-gdb/Debug/ld/ld-new --export-dynamic a.o -o a && readelf -W -s a | grep ifunc 7: 0000000000401008 0 IFUNC GLOBAL DEFAULT 3 ifunc % ~/Dev/binutils-gdb/Debug/ld/ld-new --export-dynamic a.o ./b.so -o a && readelf -W -s a | grep ifunc 5: 0000000000401010 0 FUNC GLOBAL DEFAULT 7 ifunc 8: 0000000000401010 0 FUNC GLOBAL DEFAULT 7 ifunc % ~/Dev/binutils-gdb/Debug/ld/ld-new --export-dynamic -pie a.o -o a && readelf -W --dyn-syms a | grep ifunc 5: 0000000000001020 0 IFUNC GLOBAL DEFAULT 8 ifunc % ~/Dev/binutils-gdb/Debug/ld/ld-new --export-dynamic -pie a.o ./b.so -o a && readelf -W --dyn-syms a | grep ifunc 5: 0000000000001020 0 IFUNC GLOBAL DEFAULT 8 ifunc Is this a -no-pie only behavior? -- You are receiving this mail because: You are on the CC list for the bug.
