Nathan: is your version of llvm-objcopy later than r359639 (April 30)?
From: Nathan Chancellor <natechancel...@gmail.com> Date: Mon, May 13, 2019 at 4:29 PM To: Nick Desaulniers Cc: <keesc...@chromium.org>, <clang-built-li...@googlegroups.com>, Nathan Chancellor, Jordan Rupprect, Arnd Bergmann, Greg Kroah-Hartman, <linux-kernel@vger.kernel.org> > On Mon, May 13, 2019 at 03:21:09PM -0700, 'Nick Desaulniers' via Clang Built > Linux wrote: > > 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. > > > > 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 in the Flags field that .text is now renamed .rodata, the > > append flag A is set, and the section is not flagged as writeable W. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/448 > > Reported-by: Nathan Chancellor <nathancha...@gmail.com> > > This should be natechancel...@gmail.com (although I think I do own that > email, just haven't been into it for 10+ years...) > > > Suggested-by: Jordan Rupprect <ruppre...@google.com> > > Signed-off-by: Nick Desaulniers <ndesaulni...@google.com> > > --- > > drivers/misc/lkdtm/Makefile | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile > > index 951c984de61a..89dee2a9d88c 100644 > > --- a/drivers/misc/lkdtm/Makefile > > +++ b/drivers/misc/lkdtm/Makefile > > @@ -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 > > targets += rodata.o rodata_objcopy.o > > $(obj)/rodata_objcopy.o: $(obj)/rodata.o FORCE > > $(call if_changed,objcopy) > > -- > > 2.21.0.1020.gf2820cf01a-goog > > > > I ran this script to see if there was any change for GNU objcopy and it > looks like .rodata's type gets changed, is this intentional? Otherwise, > this works for llvm-objcopy like you show. > > ----------- > > 1c1 > < There are 11 section headers, starting at offset 0x240: > --- > > There are 11 section headers, starting at offset 0x230: > 8c8 > < [ 1] .rodata PROGBITS 0000000000000000 00000040 > --- > > [ 1] .rodata NOBITS 0000000000000000 00000040 > 10c10 > > ----------- > > #!/bin/bash > > TMP1=$(mktemp) > TMP2=$(mktemp) > > git checkout next-20190513 > > make -j$(nproc) ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- O=out mrproper > allyesconfig drivers/misc/lkdtm/ > readelf -S out/drivers/misc/lkdtm/rodata_objcopy.o > ${TMP1} > > curl -LSs > https://lore.kernel.org/lkml/20190513222109.110020-1-ndesaulni...@google.com/raw > | git am -3 > > make -j$(nproc) ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- O=out mrproper > allyesconfig drivers/misc/lkdtm/ > readelf -S out/drivers/misc/lkdtm/rodata_objcopy.o > ${TMP2} > > diff ${TMP1} ${TMP2}
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