krytarowski added a comment. In D56554#1354885 <https://reviews.llvm.org/D56554#1354885>, @ruiu wrote:
> In D56554#1353572 <https://reviews.llvm.org/D56554#1353572>, @krytarowski > wrote: > > > What do you think about this new logic: > > > > 1. specified `-z execstack` -> do not emit GNU STACK segment > > 2. specified `-z noexecstack` -> emit GNU STACK segment > > 3. no option specified -> detect `findSection(".note.GNU-stack")` (I might > > miss offhand some details here to be sure if it is reliable) 3.1. detected > > -> emit GNU STACK segment 3.2. not detected -> do not emit GNU STACK segment > > > > Additionally we will specify explicitly in the clang driver for Linux and > > FreeBSD `-z noexecstack`. > > > I think I don't like the very idea of using "marker sections" in input object > files to change the linker behavior. That's too subtle and seems error-prone > to me. > > After thinking for a while, I started thinking that the first version of this > patch is probably exactly what we want. I had been thinking that `-z > {no,}execstack` and `-z {no,}gnustack` are four different options, but what > we actually want to get is tri-state: > > - emit PT_GNU_STACK with RWX permission > - emit PT_GNU_STACK with RW permission > - do not emit PT_GNU_STACK > > So we could map them to `-z {execstack,noexecstack,nognustack}`, > respectively, with default set to `-z noexecstack`. You guys can pass `-z > nognustack` to the linker to tell the linker to not emit it at all. That's > exactly this patch does. Actually after a longer thought, I recommend to hardcode inside lld a check for `TargetTriple.isOSNetBSD()`. Using `-z nognustack` isn't portable to other linkers. ================ Comment at: ELF/Writer.cpp:1979 - // PT_GNU_STACK is a special section to tell the loader to make the - // pages for the stack non-executable. If you really want an executable - // stack, you can pass -z execstack, but that's not recommended for - // security reasons. - unsigned Perm = PF_R | PF_W; - if (Config->ZExecstack) - Perm |= PF_X; - AddHdr(PT_GNU_STACK, Perm)->p_memsz = Config->ZStackSize; + if (!Config->ZNognustack) { + // PT_GNU_STACK is a special section to tell the loader to make the ---------------- Please go for `if (!Config->TargetTriple.isOSNetBSD()) {` Repository: rLLD LLVM Linker CHANGES SINCE LAST ACTION https://reviews.llvm.org/D56554/new/ https://reviews.llvm.org/D56554 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
