Re: [PATCH 2/2] selftests/fpu: Add an FPU selftest

[kernel test robot]

In-Reply-To: <202006191741...@alien8.de>
References: <202006191741...@alien8.de>
TO: Borislav Petkov <b...@alien8.de>
TO: X86 ML <x...@kernel.org>
CC: j...@kernelbug.mail.kapsi.fi
CC: Dave Hansen <dave....@intel.com>
CC: LKML <linux-...@vger.kernel.org>

Hi Borislav,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kselftest/next]
[also build test ERROR on tip/auto-latest linus/master v5.8-rc1 next-20200618]
[cannot apply to tip/x86/core]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use as documented in
https://git-scm.com/docs/git-format-patch]

url: https://github.com/0day-ci/linux/commits/Borislav-Petkov/x86-FPU-FPU-sanitization-for-in-kernel-use/20200620-014453
base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
config: x86_64-allyesconfig (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 487ca07fcc75d52755c9fe2ee05bcb3b6eeeec44)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install x86_64 cross compiling tool for clang build
# apt-get install binutils-x86-64-linux-gnu
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <l...@intel.com>

All errors (new ones prefixed by >>):

>> ld.lld: error: undefined symbol: __adddf3
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a
--
>> ld.lld: error: undefined symbol: __muldf3
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a
--
>> ld.lld: error: undefined symbol: __divdf3
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a
--
>> ld.lld: error: undefined symbol: __gtdf2
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a
>>> referenced by test_fpu.c
>>> test_fpu.o:(test_fpu_get) in archive lib/built-in.a

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuil...@lists.01.org

[kernel test robot]

Hi Borislav,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kselftest/next]
[also build test ERROR on tip/auto-latest linus/master v5.8-rc1 next-20200618]
[cannot apply to tip/x86/core]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use as documented in
https://git-scm.com/docs/git-format-patch]

url: https://github.com/0day-ci/linux/commits/Borislav-Petkov/x86-FPU-FPU-sanitization-for-in-kernel-use/20200620-014453
base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next

config: x86_64-allmodconfig (attached as .config)

compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 487ca07fcc75d52755c9fe2ee05bcb3b6eeeec44)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install x86_64 cross compiling tool for clang build
# apt-get install binutils-x86-64-linux-gnu
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <l...@intel.com>

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "__gtdf2" [lib/test_fpu.ko] undefined!
>> ERROR: modpost: "__divdf3" [lib/test_fpu.ko] undefined!
>> ERROR: modpost: "__muldf3" [lib/test_fpu.ko] undefined!
>> ERROR: modpost: "__adddf3" [lib/test_fpu.ko] undefined!

[Borislav Petkov]

Hmm, the point here is to actually have SSE* code in a kernel module for
testing. And gcc does the right thing, see below.

LLVM folks, how can I make llvm not call those library functions and
actually spit out SSE* code?

Full build command is:

/mnt/smr/share/src/llvm/tc-build/install/bin/clang-11 -Wp,-MMD,lib/.test_fpu.o.d -nostdinc -isystem /mnt/smr/share/src/llvm/tc-build/install/lib/clang/11.0.0/include -I./arch/x86/include -I./arch/x86/include/generated -I./include -I./arch/x86/include/uapi -I./arch/x86/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 -no-integrated-as -Werror=unknown-warning-option -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mstack-alignment=8 -march=k8 -mno-red-zone -mcmodel=kernel -Wno-sign-compare -fno-asynchronous-unwind-tables -mretpoline-external-thunk -fno-delete-null-pointer-checks -Wno-frame-address -Wno-address-of-packed-member -O2 -Wframe-larger-than=2048 -fstack-protector -Wno-format-invalid-specifier -Wno-gnu -mno-global-merge -Wno-unused-const-variable -g -DCC_USING_FENTRY -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=./= -fcf-protection=none -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -Wno-pointer-to-enum-cast -Wno-tautological-constant-out-of-range-compare -mhard-float -msse -DMODULE -DKBUILD_BASENAME='"test_fpu"' -DKBUILD_MODNAME='"test_fpu"' -c -o lib/test_fpu.o lib/test_fpu.c

Thx.

--- /tmp/test_fpu.s.gcc 2020-06-22 18:51:25.828615337 +0200
+++ /tmp/test_fpu.s.llvm-11 2020-06-22 18:50:35.080614534 +0200
@@ -1,74 +1,49 @@
-test_fpu_get:
- pushq %r12 #
- pushq %rbx #
- movq %rsi, %rbx # tmp119, val
- subq $56, %rsp #,
-# lib/test_fpu.c:58: kernel_fpu_begin();
- call kernel_fpu_begin #
-# lib/test_fpu.c:32: a = 4.0;
- movlpd .LC1(%rip), %xmm0 #, tmp106
- movsd %xmm0, (%rsp) # tmp106, a
-# lib/test_fpu.c:33: b = 1e-15;
- movlpd .LC2(%rip), %xmm0 #, tmp107
- movsd %xmm0, 8(%rsp) # tmp107, b
-# lib/test_fpu.c:34: c = 1e-310;
- movlpd .LC3(%rip), %xmm0 #, tmp108
- movsd %xmm0, 16(%rsp) # tmp108, c
-# lib/test_fpu.c:37: d = a + b;
- movlpd (%rsp), %xmm0 # a, a.2_8
- movlpd 8(%rsp), %xmm1 # b, b.3_9
- addsd %xmm1, %xmm0 # b.3_9, _10
-# lib/test_fpu.c:37: d = a + b;
- movsd %xmm0, 24(%rsp) # _10, d
-# lib/test_fpu.c:40: e = a + b / 2;
- movlpd 8(%rsp), %xmm0 # b, b.4_11
-# lib/test_fpu.c:40: e = a + b / 2;
- movlpd (%rsp), %xmm1 # a, a.5_13
-# lib/test_fpu.c:40: e = a + b / 2;
- mulsd .LC4(%rip), %xmm0 #, tmp109
-# lib/test_fpu.c:40: e = a + b / 2;
- addsd %xmm1, %xmm0 # a.5_13, _14
-# lib/test_fpu.c:40: e = a + b / 2;
- movsd %xmm0, 32(%rsp) # _14, e
-# lib/test_fpu.c:43: f = b / c;
- movlpd 8(%rsp), %xmm0 # b, b.6_15
- movlpd 16(%rsp), %xmm1 # c, c.7_16
- divsd %xmm1, %xmm0 # c.7_16, _17
-# lib/test_fpu.c:43: f = b / c;
- movsd %xmm0, 40(%rsp) # _17, f
-# lib/test_fpu.c:46: g = a + c * f;
- movlpd 16(%rsp), %xmm0 # c, c.8_18
- movlpd 40(%rsp), %xmm2 # f, f.9_19
-# lib/test_fpu.c:46: g = a + c * f;
- movlpd (%rsp), %xmm1 # a, a.10_21
-# lib/test_fpu.c:46: g = a + c * f;
- mulsd %xmm2, %xmm0 # f.9_19, tmp111
-# lib/test_fpu.c:46: g = a + c * f;
- addsd %xmm1, %xmm0 # a.10_21, _22
-# lib/test_fpu.c:46: g = a + c * f;
- movsd %xmm0, 48(%rsp) # _22, g
-# lib/test_fpu.c:48: if (d > a && e > a && g > a)
- movlpd 24(%rsp), %xmm1 # d, d.11_23
- movlpd (%rsp), %xmm0 # a, a.12_24
-# lib/test_fpu.c:48: if (d > a && e > a && g > a)
- comisd %xmm0, %xmm1 # a.12_24, d.11_23
- jbe .L15 #,
-# lib/test_fpu.c:48: if (d > a && e > a && g > a)
- movlpd 32(%rsp), %xmm1 # e, e.13_25
- movlpd (%rsp), %xmm0 # a, a.14_26
-# lib/test_fpu.c:48: if (d > a && e > a && g > a)
- comisd %xmm0, %xmm1 # a.14_26, e.13_25
- jbe .L15 #,
-# lib/test_fpu.c:48: if (d > a && e > a && g > a)
- movlpd 48(%rsp), %xmm1 # g, g.15_27
-# lib/test_fpu.c:51: return -EINVAL;
- movl $0, %r12d #, tmp117
- movl $-22, %eax #, tmp118
-# lib/test_fpu.c:48: if (d > a && e > a && g > a)
- movlpd (%rsp), %xmm0 # a, a.16_28
-# lib/test_fpu.c:51: return -EINVAL;
- comisd %xmm0, %xmm1 # a.16_28, g.15_27
- cmovbe %eax, %r12d # tmp117,, tmp118, <retval>
-.L4:
-# lib/test_fpu.c:60: kernel_fpu_end();
- call kernel_fpu_end #
+test_fpu_get: # @test_fpu_get
+# %bb.0:
+ pushq %rbp
+ pushq %rbx
+ subq $56, %rsp
+ movq %rsi, %rbx
+ callq kernel_fpu_begin
+ movabsq $4616189618054758400, %rax # imm = 0x4010000000000000
+ movq %rax, (%rsp)
+ movabsq $4382569440205035030, %rax # imm = 0x3CD203AF9EE75616
+ movq %rax, 8(%rsp)
+ movabsq $20240225330731, %rax # imm = 0x12688B70E62B
+ movq %rax, 16(%rsp)
+ movq (%rsp), %rdi
+ movq 8(%rsp), %rsi
+ callq __adddf3
+ movq %rax, 48(%rsp)
+ movq (%rsp), %rbp
+ movq 8(%rsp), %rdi
+ movabsq $4602678819172646912, %rsi # imm = 0x3FE0000000000000
+ callq __muldf3
+ movq %rbp, %rdi
+ movq %rax, %rsi
+ callq __adddf3
+ movq %rax, 40(%rsp)
+ movq 8(%rsp), %rdi
+ movq 16(%rsp), %rsi
+ callq __divdf3
+ movq %rax, 32(%rsp)
+ movq (%rsp), %rbp
+ movq 16(%rsp), %rdi
+ movq 32(%rsp), %rsi
+ callq __muldf3
+ movq %rbp, %rdi
+ movq %rax, %rsi
+ callq __adddf3
+ movq %rax, 24(%rsp)
+ movq 48(%rsp), %rdi
+ movq (%rsp), %rsi
+ callq __gtdf2
+ testl %eax, %eax
+ jle .LBB3_3
+# %bb.1:
+ movq 40(%rsp), %rdi
+ movq (%rsp), %rsi
+ callq __gtdf2
+ testl %eax, %eax
+ jle .LBB3_3
+# %bb.2:

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

[Nick Desaulniers]

Add -msse2. See also:
commit e8a170ff9a35 ("drm/amdgpu: enable -msse2 for GCC 7.1+ users")
potentially relevant, though less so:
commit 00db297106e8 ("drm/amdgpu: fix stack alignment ABI mismatch for
GCC 7.1+")
commit c868868f6b6a ("drm/amdgpu: fix stack alignment ABI mismatch for Clang")
and may your stacks always share the same alignment.

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--
Thanks,
~Nick Desaulniers