llvm-strip+llvm-objcopy missing wildcard/glob support

[nickdesaulniers]

Copy pasta from @nathanchance :
https://travis-ci.com/ClangBuiltLinux/continuous-integration/jobs/199950114
https://travis-ci.com/ClangBuiltLinux/continuous-integration/jobs/199950118
https://travis-ci.com/ClangBuiltLinux/continuous-integration/jobs/199950120

Stuff along the lines of:

0000000000000000 R_AARCH64_ABS64 sort
0000000000000008 R_AARCH64_ABS64 __ksymtab_strings
drivers/firmware/efi/libstub/lib-sort.stub.o: absolute symbol references not allowed in the EFI stub

It looks like this is probably caused by llvm-strip not supporting the globs in STUBCOPY_RM-y, which @rupprecht noted here. These were removed upstream in torvalds@02562d0 because of torvalds@f922c4a. torvalds@f922c4a decently backports to 4.9 and 4.14, not so clean for 4.4. Might be wise to conditionally turn on llvm-strip.
cc @rupprecht

[rupprecht]

It sound like there's no opposition to just supporting glob characters: https://llvm.org/pr41268. But no one has gotten around to it yet.

[nathanchance]

Just as an FYI, even without llvm-strip, llvm-objcopy fails on 4.4 with:

...
000000000000013c R_AARCH64_ABS64 .init.text
0000000000000014 R_AARCH64_ABS32 .debug_frame
0000000000000018 R_AARCH64_ABS64 .init.text
000000000000003c R_AARCH64_ABS32 .debug_frame
0000000000000040 R_AARCH64_ABS64 .init.text+168
000000000000005c R_AARCH64_ABS32 .debug_frame
0000000000000060 R_AARCH64_ABS64 .init.text+192
000000000000007c R_AARCH64_ABS32 .debug_frame
0000000000000080 R_AARCH64_ABS64 .init.text+216
00000000000000ac R_AARCH64_ABS32 .debug_frame
00000000000000b0 R_AARCH64_ABS64 .init.text+628
00000000000000cc R_AARCH64_ABS32 .debug_frame
00000000000000d0 R_AARCH64_ABS64 .init.text+656
00000000000000fc R_AARCH64_ABS32 .debug_frame
0000000000000100 R_AARCH64_ABS64 .init.text+1440
000000000000012c R_AARCH64_ABS32 .debug_frame
0000000000000130 R_AARCH64_ABS64 .init.text+1740
drivers/firmware/efi/libstub/arm-stub.stub.o: absolute symbol references not allowed in the EFI stub

Same root cause it seems (drivers/firmware/efi/libstub/Makefile):

STUBCOPY_FLAGS-y		:= -R .debug* -R *ksymtab* -R *kcrctab*
...
quiet_cmd_stubcopy = STUBCPY $@
      cmd_stubcopy = if $(OBJCOPY) $(STUBCOPY_FLAGS-y) $< $@; then	\
		     $(OBJDUMP) -r $@ | grep $(STUBCOPY_RELOC-y)	\
		     && (echo >&2 "$@: absolute symbol references not allowed in the EFI stub"; \
			 rm -f $@; /bin/false); else /bin/false; fi

I don't think backporting the fixes for that is feasible, glob support would need to be added for this to work I think.

[nickdesaulniers]

patch: https://reviews.llvm.org/D66613

[rupprecht]

Finally landed just now in r375169. Closing this finally, and please let me know if it works in the kernel build!

[nathanchance]

% make -j$(nproc) -s ARCH=arm64 CC=clang CROSS_COMPILE=aarch64-linux-gnu- O=out OBJCOPY=llvm-objcopy STRIP=llvm-strip distclean defconfig all

succeeds for me on 4.4.196 with a build of LLVM at llvm/llvm-project@9a335b6.