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RISCV assembler error (illegal operands auipc) compiling arch/riscv/kernel/vdso/vgettimeofday.c #1112

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tklauser opened this issue Jul 29, 2020 · 5 comments
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RISCV assembler error (illegal operands auipc) compiling arch/riscv/kernel/vdso/vgettimeofday.c #1112

tklauser opened this issue Jul 29, 2020 · 5 comments
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[ARCH] risc-v [BUG] linux [FIXED][LINUX] 5.9

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@tklauser
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@tklauser tklauser commented Jul 29, 2020

On linux-next (next-20200728):

make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- CC=clang-11 V=1 LD=riscv64-linux-gnu-ld
[...]
  clang-11 -Wp,-MMD,arch/riscv/kernel/vdso/.vgettimeofday.o.d  -nostdinc -isystem /usr/lib/llvm-11/lib/clang/11.0.0/include -I./arch/riscv/include -I./arch/riscv/include/generated  -I./include -I./arch/riscv/include/uapi -I./arch/riscv/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -Qunused-arguments -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Wno-format-security -std=gnu89 --target=riscv64-linux-gnu --prefix=/usr/bin/ --gcc-toolchain=/usr -no-integrated-as -Werror=unknown-warning-option -mabi=lp64 -march=rv64imac -mno-save-restore -DCONFIG_PAGE_OFFSET=0xffffffe000000000 -mcmodel=medany -fno-omit-frame-pointer -fno-delete-null-pointer-checks -Wno-frame-address -Wno-address-of-packed-member -O2 -Wframe-larger-than=2048 -fstack-protector-strong -Wno-format-invalid-specifier -Wno-gnu -mno-global-merge -Wno-unused-const-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -ftrivial-auto-var-init=pattern -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wno-array-bounds -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -fmacro-prefix-map=./= -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -Wno-pointer-to-enum-cast -Wno-tautological-constant-out-of-range-compare -fPIC -include /home/tklauser/src/linux/lib/vdso/gettimeofday.c   -fsanitize=kernel-address      -DKBUILD_MODFILE='"arch/riscv/kernel/vdso/vgettimeofday"' -DKBUILD_BASENAME='"vgettimeofday"' -DKBUILD_MODNAME='"vgettimeofday"' -c -o arch/riscv/kernel/vdso/vgettimeofday.o arch/riscv/kernel/vdso/vgettimeofday.c
/tmp/vgettimeofday-1ae0d2.s: Assembler messages:
/tmp/vgettimeofday-1ae0d2.s:28: Error: bad expression
/tmp/vgettimeofday-1ae0d2.s:28: Error: illegal operands `auipc a2,%got_pcrel_hi(__stack_chk_guard)'
/tmp/vgettimeofday-1ae0d2.s:44: Error: bad expression
/tmp/vgettimeofday-1ae0d2.s:44: Error: illegal operands `auipc a2,%got_pcrel_hi(__vdso_clock_gettime)'
/tmp/vgettimeofday-1ae0d2.s:371: Error: bad expression
/tmp/vgettimeofday-1ae0d2.s:371: Error: illegal operands `auipc a1,%got_pcrel_hi(__stack_chk_guard)'
/tmp/vgettimeofday-1ae0d2.s:556: Error: bad expression
/tmp/vgettimeofday-1ae0d2.s:556: Error: illegal operands `auipc a2,%got_pcrel_hi(__stack_chk_guard)'
/tmp/vgettimeofday-1ae0d2.s:571: Error: bad expression
/tmp/vgettimeofday-1ae0d2.s:571: Error: illegal operands `auipc a1,%got_pcrel_hi(__vdso_gettimeofday)'
/tmp/vgettimeofday-1ae0d2.s:879: Error: bad expression
/tmp/vgettimeofday-1ae0d2.s:879: Error: illegal operands `auipc a1,%got_pcrel_hi(__stack_chk_guard)'
clang: error: assembler command failed with exit code 1 (use -v to see invocation)
make[3]: *** [scripts/Makefile.build:281: arch/riscv/kernel/vdso/vgettimeofday.o] Error 1
make[2]: *** [scripts/Makefile.build:497: arch/riscv/kernel/vdso] Error 2
make[1]: *** [scripts/Makefile.build:497: arch/riscv/kernel] Error 2
make: *** [Makefile:1756: arch/riscv] Error 2
@tklauser tklauser changed the title RISCV assembler issues (illegal operands auipc) compiling arch/riscv/kernel/vdso/vgettimeofday.c RISCV assembler error (illegal operands auipc) compiling arch/riscv/kernel/vdso/vgettimeofday.c Jul 29, 2020
@tklauser
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@tklauser tklauser commented Jul 29, 2020

/tmp/vgettimeofday-1ae0d2.s:28: Error: bad expression
/tmp/vgettimeofday-1ae0d2.s:28: Error: illegal operands `auipc a2,%got_pcrel_hi(__stack_chk_guard)'

These are caused by missing -fno-stack-protector when building vDSO, addressed by https://lore.kernel.org/linux-riscv/20200729075129.11538-1-tklauser@distanz.ch/T/#u

Still looking into the ones regarding __vdso_clock_gettime and __vdso_gettimeofday.
@nickdesaulniers
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@nickdesaulniers nickdesaulniers commented Jul 29, 2020

It looks like you're doing a non-IAS build; our CI coverage is doing make LLVM=1 LLVM_IAS=1 builds for RISCV, so I'm not surprised that clang may be emitting assembler that's not valid for GNU as. -fstack-protector is also causing issues recently in #1092 . I'm not sure turning off the stack protector is the ultimate fix (sounds like we should fix Clang) rather than a workaround. Please use scripts/get_maintainer.pl when sending patches in order to cc our mailing list (clang-built-linux@googlegroups.com).
@tklauser
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@tklauser tklauser commented Jul 30, 2020

It looks like you're doing a non-IAS build; our CI coverage is doing make LLVM=1 LLVM_IAS=1 builds for RISCV, so I'm not surprised that clang may be emitting assembler that's not valid for GNU as. -fstack-protector is also causing issues recently in #1092 . I'm not sure turning off the stack protector is the ultimate fix (sounds like we should fix Clang) rather than a workaround.

Thanks for the info, with LLVM_IAS it works indeed. I was assuming we might need to disable the stack protector for the vDSO since this seems to be what other archs do.

Please use scripts/get_maintainer.pl when sending patches in order to cc our mailing list (clang-built-linux@googlegroups.com).

Will do, thanks.
ruscur pushed a commit to ruscur/linux that referenced this issue Aug 3, 2020
@tklauser @palmer-dabbelt
riscv: disable stack-protector for vDSO
Unverified
This user has not uploaded their public key yet.
GPG key ID: 2E1319F35FBB1889 Learn about signing commits
1b4cab5 
Currently, building the vDSO with clang leads assembler errors like the
following:

  /tmp/vgettimeofday-1ae0d2.s: Assembler messages:
  /tmp/vgettimeofday-1ae0d2.s:28: Error: bad expression
  /tmp/vgettimeofday-1ae0d2.s:28: Error: illegal operands `auipc a2,%got_pcrel_hi(__stack_chk_guard)'

Disable the stack-protector for vDSO to fix these.

Link: ClangBuiltLinux#1112
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
ruscur pushed a commit to ruscur/linux that referenced this issue Aug 5, 2020
@tklauser @palmer-dabbelt
riscv: disable stack-protector for vDSO
Unverified
This user has not uploaded their public key yet.
GPG key ID: 2E1319F35FBB1889 Learn about signing commits
40284a0 
Currently, building the vDSO with clang leads assembler errors like the
following:

  /tmp/vgettimeofday-1ae0d2.s: Assembler messages:
  /tmp/vgettimeofday-1ae0d2.s:28: Error: bad expression
  /tmp/vgettimeofday-1ae0d2.s:28: Error: illegal operands `auipc a2,%got_pcrel_hi(__stack_chk_guard)'

Disable the stack-protector for vDSO to fix these.

Link: ClangBuiltLinux#1112
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
esmil added a commit to esmil/linux that referenced this issue Aug 15, 2020
@tklauser @esmil
riscv: disable stack-protector for vDSO
9294561 
Currently, building the vDSO with clang leads assembler errors like the
following:

  /tmp/vgettimeofday-1ae0d2.s: Assembler messages:
  /tmp/vgettimeofday-1ae0d2.s:28: Error: bad expression
  /tmp/vgettimeofday-1ae0d2.s:28: Error: illegal operands `auipc a2,%got_pcrel_hi(__stack_chk_guard)'

Disable the stack-protector for vDSO to fix these.

Link: ClangBuiltLinux#1112
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
@nathanchance
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@nathanchance nathanchance commented Aug 26, 2020

Looks like our mailing list was never CC'd on that patch: https://lore.kernel.org/linux-riscv/20200729075129.11538-1-tklauser@distanz.ch/

It has been merged into mainline: https://git.kernel.org/linus/40284a072c42f6177184fb1f62ba94c69e0c0277

As it turns out, that patch fixes #1092. This appears normal for the vDSO based on arm, arm64, and x86 so I would not consider this a bug in clang or anything.
@tklauser
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@tklauser tklauser commented Aug 26, 2020

Thank you @nathanchance and sorry about not Cc'ing the mailing list on the patch. Will make sure to do so for any future patches.
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@tklauser @nickdesaulniers @nathanchance