drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: warning: objtool: .text.rtl92cu_hw_init: unexpected end of section #1613

dileks · 2022-03-24T10:58:47Z

I see this new objtool warning when using LLVM-14 version 14.0.0 (Debian or selfmade/stage1-only) and CONFIG_LTO_CLANG_THIN=y:

drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: warning: objtool: .text.rtl92cu_hw_init: unexpected end of section

With LLVM-13 v13.0.0 I do not see it.

On a first view in the issue-tracker I have not seen this reported.

The text was updated successfully, but these errors were encountered:

dileks · 2022-03-24T11:10:28Z

Here my kernel-config.

config-5.17.0-2-amd64-clang14-lto.txt

dileks · 2022-03-24T12:18:54Z

My make line:

/usr/bin/perf stat make V=1 -j4 LLVM=1 LLVM_IAS=1 PAHOLE=/opt/pahole/bin/pahole LOCALVERSION=-2-amd64-clang14-lto KBUILD_BUILD_HOST=iniza KBUILD_BUILD_USER=sedat.dilek@gmail.com KBUILD_BUILD_TIMESTAMP=2022-03-24 bindeb-pkg KDEB_PKGVERSION=5.17.0-2~bookworm+dileks1

nathanchance · 2022-03-24T15:18:40Z

I suspect this is just one instance of #1480. You could try to verify it by adding KCFLAGS="-Xclang -no-enable-noundef-analysis" to your make invocation to see if the warning disappears (or changes).

dileks · 2022-03-24T18:59:51Z

This here seems not to work:

--- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile
@@ -10,4 +10,8 @@ rtl8192cu-objs :=             \
                table.o         \
                trx.o
 
+# CBL issue #1613
+# https://github.com/ClangBuiltLinux/linux/issues/1613
+CFLAGS_rtl8192cu.o += -Xclang -no-enable-noundef-analysis
+
 obj-$(CONFIG_RTL8192CU) += rtl8192cu.o

dileks · 2022-03-24T20:24:30Z

I do not want to re-compile the whole Linux-kernel again by passing KCFLAGS to make.

Looks like this will be in LLVM-15:

$ git describe --contains 1b1c8d83d3567a60280291c0adb95d1d60335509
llvmorg-15-init~2146

$ git log --oneline -1 1b1c8d83d3567a60280291c0adb95d1d60335509
1b1c8d83d356 [Clang/Test]: Rename enable_noundef_analysis to disable-noundef-analysis and turn it off by default

With this diff:

--- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile
@@ -1,4 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
+
+# https://github.com/ClangBuiltLinux/linux/issues/1613
+ccflags-y += -disable-noundef-analysis
+
 rtl8192cu-objs :=              \
                dm.o            \
                hw.o            \

Nope.

$ grep disable-noundef-analysis ../build-log_5.17.0-2-amd64-clang14-lto.txt | wc -l
18

$ grep warning: ../build-log_5.17.0-2-amd64-clang14-lto.txt 
9:dpkg-architecture: warning: specified GNU system type x86_64-linux-gnu does not match CC system type x86_64-unknown-linux-gnu, try setting a correct CC environment variable
4019:drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: warning: objtool: .text.rtl92cu_hw_init: unexpected end of section

dileks · 2022-03-24T20:27:22Z

Just as a note:

$ /opt/llvm-toolchain/bin/clang -cc1 --help | grep -A1 disable-noundef-analysis
  -disable-noundef-analysis
                          Disable analyzing function argument and return types for mandatory definedness

$ /opt/llvm-toolchain/bin/clang -v
dileks clang version 14.0.0 (https://github.com/llvm/llvm-project.git 3f43d803382d57e3fc010ca19833077d1023e9c9)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/llvm-toolchain/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64

nathanchance · 2022-03-24T20:28:22Z

With this diff:

--- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile
@@ -1,4 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
+
+# https://github.com/ClangBuiltLinux/linux/issues/1613
+ccflags-y += -disable-noundef-analysis
+
 rtl8192cu-objs :=              \
                dm.o            \
                hw.o            \

Nope.

ccflags-y += -Xclang -disable-noundef-analysis

dileks · 2022-03-24T20:36:04Z

Nope.

3462:  clang -Wp,-MMD,drivers/net/wireless/realtek/rtlwifi/rtl8192cu/.dm.o.d -nostdinc -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/compiler-version.h -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -Qunused-arguments -fmacro-prefix-map=./= -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Werror=return-type -Wno-format-security -std=gnu11 --target=x86_64-linux-gnu -fintegrated-as -Werror=unknown-warning-option -Werror=ignored-optimization-argument -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -fcf-protection=none -m64 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387 -mstack-alignment=8 -mskip-rax-setup -mtune=generic -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-strong -Wimplicit-fallthrough -Wno-gnu -mno-global-merge -Wno-unused-but-set-variable -Wno-unused-const-variable -fno-stack-clash-protection -pg -mfentry -DCC_USING_NOP_MCOUNT -DCC_USING_FENTRY -fno-lto -flto=thin -fsplit-lto-unit -fvisibility=hidden -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wcast-function-type -Wno-array-bounds -fno-strict-overflow -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -Wno-pointer-to-enum-cast -Wno-tautological-constant-out-of-range-compare -Wno-unaligned-access -g -gdwarf-5 -Xclang -no-enable-noundef-analysis  -DMODULE  -DKBUILD_BASENAME='"dm"' -DKBUILD_MODNAME='"rtl8192cu"' -D__KBUILD_MODNAME=kmod_rtl8192cu -c -o drivers/net/wireless/realtek/rtlwifi/rtl8192cu/dm.o drivers/net/wireless/realtek/rtlwifi/rtl8192cu/dm.c 
3463:error: unknown argument: '-no-enable-noundef-analysis'

nathanchance · 2022-03-24T20:41:41Z

Ah, the flag was only renamed in main, my apologies (I did correct it after the fact but that is not obvious): llvm/llvm-project@b529744

Regardless, if I add ccflags-y += -Xclang -disable-noundef-analysis or the equivalent for LLVM main to drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile, the warning goes away, so this is indeed just another instance of #1480.

I won't dupe this report for now though, as this might be a bug in the kernel sources.

nickdesaulniers · 2022-03-24T20:42:11Z

https://reviews.llvm.org/rGb529744c29a87d8ecf4336e751fee794df10ec7f

dileks · 2022-03-24T20:47:28Z

This fixes the warning for me:

--- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile
+++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile
@@ -1,4 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
+
+# https://github.com/ClangBuiltLinux/linux/issues/1613
+ccflags-y += -Xclang -disable-noundef-analysis
+
 rtl8192cu-objs :=              \
                dm.o            \
                hw.o            \

nickdesaulniers · 2022-03-24T22:57:31Z

@dileks can you please supply the output of llvm-objdump -Dr --disassemble-symbols=.text.rtl92cu_hw_init drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o. Consider attaching a file if the output is larger than 10 lines of asm.

dileks · 2022-03-25T04:02:11Z

@nickdesaulniers

With and without patch:

$ llvm-objdump-14 -Dr --disassemble-symbols=.text.rtl92cu_hw_init drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o 

drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: file format elf64-x86-64
llvm-objdump-14: warning: 'drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o': failed to disassemble missing symbol .text.rtl92cu_hw_init

NOTE: I have commented the ccflags line and have re-run my build-script.

dileks · 2022-03-25T04:29:05Z

Checking again:

$ llvm-objdump-14 -Dr drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o | grep hw_init | grep -i disass
Disassembly of section .text.rtl92cu_hw_init:
Disassembly of section .rela.text.rtl92cu_hw_init:

$ llvm-objdump-14 -Dr --disassemble-symbols=.text.rtl92cu_hw_init drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o

drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: file format elf64-x86-64
llvm-objdump-14: warning: 'drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o': failed to disassemble missing symbol .text.rtl92cu_hw_init

$ llvm-objdump-14 -Dr --disassemble-symbols=.rela.text.rtl92cu_hw_init drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o
File: llvm-objdump-14_rtl8192cu_lto_o-rela_text_rtl92cu_hw_init.txt

Attached output of the last {.rela}.text.rtl92cu_hw_init.

llvm-objdump-14_rtl8192cu_lto_o-text_rtl92cu_hw_init.txt

llvm-objdump-14_rtl8192cu_lto_o-rela_text_rtl92cu_hw_init.txt

dileks · 2022-03-25T04:34:23Z

Seeing:

$ llvm-objdump-14 -Dr drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o | grep -n -A2 'Disassembly of section' | grep text.rtl92cu_hw_init
1263579:Disassembly of section .text.rtl92cu_hw_init:
1264711:Disassembly of section .rela.text.rtl92cu_hw_init:
1264713-0000000000000000 <.rela.text.rtl92cu_hw_init>:

dileks · 2022-03-25T05:07:49Z

@nickdesaulniers

I can send you the llvm-objdumps if you desire.

$ zstd -19 -T0 -v <file>

$ du -k *.txt.zst
5352    llvm-objdump-14_rtl8192cu_lto_o_BAD.txt.zst
5360    llvm-objdump-14_rtl8192cu_lto_o_GOOD.txt.zst

dileks · 2022-03-25T05:15:38Z

For the posterity:

$ grep warning: build-log_5.17.0-3-amd64-clang14-lto.txt 
27:dpkg-architecture: warning: specified GNU system type x86_64-linux-gnu does not match CC system type x86_64-pc-linux-gnu, try setting a correct CC environment variable

$ egrep 'chacha|rtl' patches.series 
6:5a822a5f4c6a rtlwifi: rtl8192cu: Fix warning with LLVM-14
7:90bac147c484 x86/chacha20: Avoid spurious jumps to other functions

[ Update 2022-03-25 ] Patch of PeterZ crypto: x86/chacha20 - Avoid spurious jumps to other functionnow in crypto-2.6.git:
https://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6.git/commit/?id=4327d168515fd8b5b92fa1efdf1d219fb6514460

dileks · 2022-03-31T13:36:28Z

Re-checking:

1263666:Disassembly of section .text.rtl92cu_hw_init:
1263667-
1263668-0000000000000000 <rtl92cu_hw_init>:

1264808:Disassembly of section .rela.text.rtl92cu_hw_init:
1264809-
1264810-0000000000000000 <.rela.text.rtl92cu_hw_init>:

Looks like .text. prefix is removed in case of section .text.rtl92cu_hw_init.

UPDATE: For both cases BAD and GOOD the same.

dileks · 2022-03-31T13:39:40Z

Attached output of:

llvm-objdump-14 -Dr --disassemble-symbols=rtl92cu_hw_init drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o > ../llvm-objdump-14-Dr-disassemble_symbols-rtl92cu_hw_init_rtl8192cu-lto-o.txt

llvm-objdump-14-Dr-disassemble_symbols-rtl92cu_hw_init_rtl8192cu-lto-o.txt

dileks · 2022-03-31T13:52:38Z

Above was with my patch applied and from my today's build.

Here now without (BAD) and with my patch (GOOD):

cd BAD
llvm-objdump-14 -Dr --disassemble-symbols=rtl92cu_hw_init rtl8192cu.lto.o > BAD_rtl92cu_hw_init.txt

cd GOOD
llvm-objdump-14 -Dr --disassemble-symbols=rtl92cu_hw_init rtl8192cu.lto.o > GOOD_rtl92cu_hw_init.txt

BAD_rtl92cu_hw_init.txt
GOOD_rtl92cu_hw_init.txt

dileks · 2022-05-21T19:16:31Z

See this issue with Linux v5.18-rc7+.

38982:drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.prelink.o: warning: objtool: .text.rtl92cu_hw_init: unexpected end of section

dileks · 2022-07-17T17:57:34Z

[ drivers/net/wireless/realtek/rtlwifi/rtl8192cu/Makefile ]
# SPDX-License-Identifier: GPL-2.0

# https://github.com/ClangBuiltLinux/linux/issues/1613
# LLVM-14
ccflags-y += $(call cc-option, -Xclang -disable-noundef-analysis)
# LLVM-15
ccflags-y += $(call cc-option, -Xclang -no-enable-noundef-analysis)

Is there a more elegant way to check for the LLVM version?

nickdesaulniers · 2022-07-18T17:49:20Z

I'm not yet convinced that noundef-analysis is broken; I don't think disabling the analysis in Kbuild is the way to go.

@dileks can you confirm that you don't have CONFIG_UBSAN_DIV_ZERO=y set in your .config? Otherwise, based on this comment, I think this may be a dupe of #1657.

dileks · 2022-07-23T20:24:06Z

@nickdesaulniers

# grep CONFIG_UBSAN_DIV_ZERO /boot/config-5.19.0-rc6-1-amd64-clang15-lto
[empty]

Full kernel-config attached.

config-5.19.0-rc6-1-amd64-clang15-lto.txt

dileks · 2022-08-07T03:35:46Z

With patch applied (no objtool warnings):

$ /opt/llvm/bin/llvm-objdump -Dr --section=".text.rtl92cu_hw_init" drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.o > ../llvm-objdump_rtl8192cu_o.txt

llvm-objdump_rtl8192cu_o.txt
config-5.19.0-3-amd64-clang15-kcfi.txt

dileks · 2022-08-07T10:18:16Z

@jpoimboe

Attached llvm-objdump without patch applied (objtool warning visible).

I can provide both object-files if needed.

llvm-objdump_rtl8192cu_o_BROKEN.txt

jpoimboe · 2022-08-19T02:24:34Z

@dileks I'm not sure about this one, please provide the .o file for the broken case and I can take a look.

dileks added [ARCH] x86_64 This bug impacts ARCH=x86_64 [TOOL] objtool warning is produced by the kernel's objtool [FEATURE] LTO Related to building the kernel with LLVM Link Time Optimization labels Mar 24, 2022

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drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: warning: objtool: .text.rtl92cu_hw_init: unexpected end of section #1613

drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: warning: objtool: .text.rtl92cu_hw_init: unexpected end of section #1613

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drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: warning: objtool: .text.rtl92cu_hw_init: unexpected end of section #1613

drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rtl8192cu.lto.o: warning: objtool: .text.rtl92cu_hw_init: unexpected end of section #1613

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