Commit cd05fb74 authored by Nick Desaulniers's avatar Nick Desaulniers Committed by Greg Kroah-Hartman

lkdtm: support llvm-objcopy

commit e9e08a07 upstream.

With CONFIG_LKDTM=y and make OBJCOPY=llvm-objcopy, llvm-objcopy errors:
llvm-objcopy: error: --set-section-flags=.text conflicts with
--rename-section=.text=.rodata

Rather than support setting flags then renaming sections vs renaming
then setting flags, it's simpler to just change both at the same time
via --rename-section. Adding the load flag is required for GNU objcopy
to mark .rodata Type as PROGBITS after the rename.

This can be verified with:
$ readelf -S drivers/misc/lkdtm/rodata_objcopy.o
...
Section Headers:
  [Nr] Name              Type             Address           Offset
       Size              EntSize          Flags  Link  Info  Align
...
  [ 1] .rodata           PROGBITS         0000000000000000  00000040
       0000000000000004  0000000000000000   A       0     0     4
...

Which shows that .text is now renamed .rodata, the alloc flag A is set,
the type is PROGBITS, and the section is not flagged as writeable W.

Cc: stable@vger.kernel.org
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=24554
Link: https://github.com/ClangBuiltLinux/linux/issues/448Reported-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Suggested-by: default avatarAlan Modra <amodra@gmail.com>
Suggested-by: default avatarJordan Rupprect <rupprecht@google.com>
Suggested-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Signed-off-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent efb27acc
......@@ -15,8 +15,7 @@ KCOV_INSTRUMENT_rodata.o := n
OBJCOPYFLAGS :=
OBJCOPYFLAGS_rodata_objcopy.o := \
--set-section-flags .text=alloc,readonly \
--rename-section .text=.rodata
--rename-section .text=.rodata,alloc,readonly,load
targets += rodata.o rodata_objcopy.o
$(obj)/rodata_objcopy.o: $(obj)/rodata.o FORCE
$(call if_changed,objcopy)
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