* objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y
@ 2022-07-13 15:47 Nathan Chancellor
2022-07-13 16:01 ` Nick Desaulniers
0 siblings, 1 reply; 7+ messages in thread
From: Nathan Chancellor @ 2022-07-13 15:47 UTC (permalink / raw)
To: Josh Poimboeuf, Peter Zijlstra; +Cc: linux-kernel, llvm
Hi Josh and Peter,
After commit 9bb2ec608a20 ("objtool: Update Retpoline validation") and
commit f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs"), I
see a spew of objtool warnings when building certain configurations with
clang. Examples below, they appear to trigger in every single file.
With x86_64_defconfig + CONFIG_KASAN=y:
arch/x86/ia32/audit.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build
arch/x86/ia32/audit.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build
init/version.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build
init/version.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build
arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build
arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build
arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build
arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build
arch/x86/kernel/platform-quirks.o: warning: objtool: asan.module_ctor+0x0: 'naked' return found in RETHUNK build
init/calibrate.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build
init/calibrate.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build
With x86_64_defconfig + CONFIG_KCSAN=y:
arch/x86/ia32/audit.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build
init/calibrate.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build
init/version.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build
arch/x86/kernel/fpu/bugs.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build
arch/x86/kernel/cpu/rdrand.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build
arch/x86/events/probe.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build
arch/x86/kernel/apic/ipi.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build
If there is any additional information I can provide or patches I can
test, I am happy to do so!
Cheers,
Nathan
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y 2022-07-13 15:47 objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y Nathan Chancellor @ 2022-07-13 16:01 ` Nick Desaulniers 2022-07-13 16:13 ` Nathan Chancellor 0 siblings, 1 reply; 7+ messages in thread From: Nick Desaulniers @ 2022-07-13 16:01 UTC (permalink / raw) To: Nathan Chancellor; +Cc: Josh Poimboeuf, Peter Zijlstra, linux-kernel, llvm On Wed, Jul 13, 2022 at 8:48 AM Nathan Chancellor <nathan@kernel.org> wrote: > > Hi Josh and Peter, > > After commit 9bb2ec608a20 ("objtool: Update Retpoline validation") and > commit f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs"), I > see a spew of objtool warnings when building certain configurations with > clang. Examples below, they appear to trigger in every single file. > > With x86_64_defconfig + CONFIG_KASAN=y: > > arch/x86/ia32/audit.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > arch/x86/ia32/audit.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > init/version.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > init/version.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > arch/x86/kernel/platform-quirks.o: warning: objtool: asan.module_ctor+0x0: 'naked' return found in RETHUNK build > init/calibrate.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > init/calibrate.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > With x86_64_defconfig + CONFIG_KCSAN=y: > > arch/x86/ia32/audit.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > init/calibrate.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > init/version.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > arch/x86/kernel/fpu/bugs.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > arch/x86/kernel/cpu/rdrand.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > arch/x86/events/probe.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > arch/x86/kernel/apic/ipi.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build Thanks for the report. I wonder if this might be a compiler bug; it seems like the {a|t}san.module_{c|d}tor functions are being emitted with ret instructions? If you have one of these builds lying around still, can you provide: $ llvm-objdump -dr --disassemble-symbols=tsan.module_ctor arch/x86/kernel/fpu/bugs.o (I'm about to head into a bunch of meetings now, but can check more this afternoon; see you at Noon) If Peter and Josh are bored, feel free to stop by https://meet.google.com/yjf-jyqk-iaz at Noon PDT / 19:00 UTV today. > > If there is any additional information I can provide or patches I can > test, I am happy to do so! > > Cheers, > Nathan > -- Thanks, ~Nick Desaulniers ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y 2022-07-13 16:01 ` Nick Desaulniers @ 2022-07-13 16:13 ` Nathan Chancellor 2022-07-13 16:25 ` Peter Zijlstra 0 siblings, 1 reply; 7+ messages in thread From: Nathan Chancellor @ 2022-07-13 16:13 UTC (permalink / raw) To: Nick Desaulniers; +Cc: Josh Poimboeuf, Peter Zijlstra, linux-kernel, llvm On Wed, Jul 13, 2022 at 09:01:58AM -0700, Nick Desaulniers wrote: > On Wed, Jul 13, 2022 at 8:48 AM Nathan Chancellor <nathan@kernel.org> wrote: > > > > Hi Josh and Peter, > > > > After commit 9bb2ec608a20 ("objtool: Update Retpoline validation") and > > commit f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs"), I > > see a spew of objtool warnings when building certain configurations with > > clang. Examples below, they appear to trigger in every single file. > > > > With x86_64_defconfig + CONFIG_KASAN=y: > > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > arch/x86/ia32/audit.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > init/version.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > init/version.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > arch/x86/kernel/platform-quirks.o: warning: objtool: asan.module_ctor+0x0: 'naked' return found in RETHUNK build > > init/calibrate.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > init/calibrate.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > With x86_64_defconfig + CONFIG_KCSAN=y: > > > > arch/x86/ia32/audit.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > init/calibrate.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > init/version.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > arch/x86/kernel/fpu/bugs.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > arch/x86/events/probe.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > arch/x86/kernel/apic/ipi.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > Thanks for the report. I wonder if this might be a compiler bug; it > seems like the {a|t}san.module_{c|d}tor functions are being emitted > with ret instructions? > > If you have one of these builds lying around still, can you provide: > > $ llvm-objdump -dr --disassemble-symbols=tsan.module_ctor > arch/x86/kernel/fpu/bugs.o Sure thing. With KASAN: $ llvm-objdump -r --disassemble-symbols=asan.module_ctor,asan.module_dtor build/arch/x86/kernel/fpu/bugs.o build/arch/x86/kernel/fpu/bugs.o: file format elf64-x86-64 Disassembly of section .text.asan.module_ctor: 0000000000000000 <asan.module_ctor>: 0: be 01 00 00 00 movl $1, %esi 5: 48 c7 c7 00 00 00 00 movq $0, %rdi 0000000000000008: R_X86_64_32S .data c: e8 00 00 00 00 callq 0x11 <asan.module_ctor+0x11> 000000000000000d: R_X86_64_PLT32 __asan_register_globals-0x4 11: c3 retq Disassembly of section .text.asan.module_dtor: 0000000000000000 <asan.module_dtor>: 0: be 01 00 00 00 movl $1, %esi 5: 48 c7 c7 00 00 00 00 movq $0, %rdi 0000000000000008: R_X86_64_32S .data c: e8 00 00 00 00 callq 0x11 <asan.module_dtor+0x11> 000000000000000d: R_X86_64_PLT32 __asan_unregister_globals-0x4 11: c3 retq With KCSAN: $ llvm-objdump -r --disassemble-symbols=tsan.module_ctor build/arch/x86/kernel/fpu/bugs.o build/arch/x86/kernel/fpu/bugs.o: file format elf64-x86-64 Disassembly of section .text.tsan.module_ctor: 0000000000000000 <tsan.module_ctor>: 0: e8 00 00 00 00 callq 0x5 <tsan.module_ctor+0x5> 0000000000000001: R_X86_64_PLT32 __tsan_init-0x4 5: c3 retq Cheers, Nathan ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y 2022-07-13 16:13 ` Nathan Chancellor @ 2022-07-13 16:25 ` Peter Zijlstra 2022-07-13 16:42 ` Nick Desaulniers 0 siblings, 1 reply; 7+ messages in thread From: Peter Zijlstra @ 2022-07-13 16:25 UTC (permalink / raw) To: Nathan Chancellor; +Cc: Nick Desaulniers, Josh Poimboeuf, linux-kernel, llvm On Wed, Jul 13, 2022 at 09:13:29AM -0700, Nathan Chancellor wrote: > On Wed, Jul 13, 2022 at 09:01:58AM -0700, Nick Desaulniers wrote: > > On Wed, Jul 13, 2022 at 8:48 AM Nathan Chancellor <nathan@kernel.org> wrote: > > > > > > Hi Josh and Peter, > > > > > > After commit 9bb2ec608a20 ("objtool: Update Retpoline validation") and > > > commit f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs"), I > > > see a spew of objtool warnings when building certain configurations with > > > clang. Examples below, they appear to trigger in every single file. > > > > > > With x86_64_defconfig + CONFIG_KASAN=y: > > > > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > init/version.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > init/version.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > arch/x86/kernel/platform-quirks.o: warning: objtool: asan.module_ctor+0x0: 'naked' return found in RETHUNK build > > > init/calibrate.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > init/calibrate.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > > With x86_64_defconfig + CONFIG_KCSAN=y: > > > > > > arch/x86/ia32/audit.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > init/calibrate.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > init/version.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > arch/x86/events/probe.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > arch/x86/kernel/apic/ipi.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > Thanks for the report. I wonder if this might be a compiler bug; it > > seems like the {a|t}san.module_{c|d}tor functions are being emitted > > with ret instructions? > > > > If you have one of these builds lying around still, can you provide: > > > > $ llvm-objdump -dr --disassemble-symbols=tsan.module_ctor > > arch/x86/kernel/fpu/bugs.o > > Sure thing. > > With KASAN: > > $ llvm-objdump -r --disassemble-symbols=asan.module_ctor,asan.module_dtor build/arch/x86/kernel/fpu/bugs.o > > build/arch/x86/kernel/fpu/bugs.o: file format elf64-x86-64 > > Disassembly of section .text.asan.module_ctor: > > 0000000000000000 <asan.module_ctor>: > 0: be 01 00 00 00 movl $1, %esi > 5: 48 c7 c7 00 00 00 00 movq $0, %rdi > 0000000000000008: R_X86_64_32S .data > c: e8 00 00 00 00 callq 0x11 <asan.module_ctor+0x11> > 000000000000000d: R_X86_64_PLT32 __asan_register_globals-0x4 > 11: c3 retq As Nick said; this should be: 'jmp __x86_return_thunk', on those builds. ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y 2022-07-13 16:25 ` Peter Zijlstra @ 2022-07-13 16:42 ` Nick Desaulniers 2022-07-13 22:05 ` Nick Desaulniers 0 siblings, 1 reply; 7+ messages in thread From: Nick Desaulniers @ 2022-07-13 16:42 UTC (permalink / raw) To: Nathan Chancellor; +Cc: Josh Poimboeuf, linux-kernel, llvm, Peter Zijlstra On Wed, Jul 13, 2022 at 9:25 AM Peter Zijlstra <peterz@infradead.org> wrote: > > On Wed, Jul 13, 2022 at 09:13:29AM -0700, Nathan Chancellor wrote: > > On Wed, Jul 13, 2022 at 09:01:58AM -0700, Nick Desaulniers wrote: > > > On Wed, Jul 13, 2022 at 8:48 AM Nathan Chancellor <nathan@kernel.org> wrote: > > > > > > > > Hi Josh and Peter, > > > > > > > > After commit 9bb2ec608a20 ("objtool: Update Retpoline validation") and > > > > commit f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs"), I > > > > see a spew of objtool warnings when building certain configurations with > > > > clang. Examples below, they appear to trigger in every single file. > > > > > > > > With x86_64_defconfig + CONFIG_KASAN=y: > > > > > > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > init/version.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > init/version.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > arch/x86/kernel/platform-quirks.o: warning: objtool: asan.module_ctor+0x0: 'naked' return found in RETHUNK build > > > > init/calibrate.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > init/calibrate.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > > > > With x86_64_defconfig + CONFIG_KCSAN=y: > > > > > > > > arch/x86/ia32/audit.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > init/calibrate.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > init/version.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > arch/x86/events/probe.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > arch/x86/kernel/apic/ipi.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > > Thanks for the report. I wonder if this might be a compiler bug; it > > > seems like the {a|t}san.module_{c|d}tor functions are being emitted > > > with ret instructions? > > > > > > If you have one of these builds lying around still, can you provide: > > > > > > $ llvm-objdump -dr --disassemble-symbols=tsan.module_ctor > > > arch/x86/kernel/fpu/bugs.o > > > > Sure thing. > > > > With KASAN: > > > > $ llvm-objdump -r --disassemble-symbols=asan.module_ctor,asan.module_dtor build/arch/x86/kernel/fpu/bugs.o > > > > build/arch/x86/kernel/fpu/bugs.o: file format elf64-x86-64 > > > > Disassembly of section .text.asan.module_ctor: > > > > 0000000000000000 <asan.module_ctor>: > > 0: be 01 00 00 00 movl $1, %esi > > 5: 48 c7 c7 00 00 00 00 movq $0, %rdi > > 0000000000000008: R_X86_64_32S .data > > c: e8 00 00 00 00 callq 0x11 <asan.module_ctor+0x11> > > 000000000000000d: R_X86_64_PLT32 __asan_register_globals-0x4 > > 11: c3 retq > > As Nick said; this should be: 'jmp __x86_return_thunk', on those builds. https://github.com/llvm/llvm-project/issues/56514 -- Thanks, ~Nick Desaulniers ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y 2022-07-13 16:42 ` Nick Desaulniers @ 2022-07-13 22:05 ` Nick Desaulniers 2022-07-14 0:31 ` Nick Desaulniers 0 siblings, 1 reply; 7+ messages in thread From: Nick Desaulniers @ 2022-07-13 22:05 UTC (permalink / raw) To: Nathan Chancellor; +Cc: Josh Poimboeuf, linux-kernel, llvm, Peter Zijlstra On Wed, Jul 13, 2022 at 9:42 AM Nick Desaulniers <ndesaulniers@google.com> wrote: > > On Wed, Jul 13, 2022 at 9:25 AM Peter Zijlstra <peterz@infradead.org> wrote: > > > > On Wed, Jul 13, 2022 at 09:13:29AM -0700, Nathan Chancellor wrote: > > > On Wed, Jul 13, 2022 at 09:01:58AM -0700, Nick Desaulniers wrote: > > > > On Wed, Jul 13, 2022 at 8:48 AM Nathan Chancellor <nathan@kernel.org> wrote: > > > > > > > > > > Hi Josh and Peter, > > > > > > > > > > After commit 9bb2ec608a20 ("objtool: Update Retpoline validation") and > > > > > commit f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs"), I > > > > > see a spew of objtool warnings when building certain configurations with > > > > > clang. Examples below, they appear to trigger in every single file. > > > > > > > > > > With x86_64_defconfig + CONFIG_KASAN=y: > > > > > > > > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > init/version.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > init/version.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > arch/x86/kernel/platform-quirks.o: warning: objtool: asan.module_ctor+0x0: 'naked' return found in RETHUNK build > > > > > init/calibrate.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > init/calibrate.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > > > > > > With x86_64_defconfig + CONFIG_KCSAN=y: > > > > > > > > > > arch/x86/ia32/audit.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > init/calibrate.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > init/version.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > arch/x86/events/probe.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > arch/x86/kernel/apic/ipi.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build It's not just the sanitizers, `CONFIG_GCOV_KERNEL=y` + `CONFIG_GCOV_PROFILE_ALL=y` also has this issue: ``` ... drivers/base/platform.o: warning: objtool: __llvm_gcov_reset+0xa94: 'naked' return found in RETHUNK build net/core/netpoll.o: warning: objtool: __llvm_gcov_reset+0xde3: 'naked' return found in RETHUNK build net/netfilter/nf_conntrack_netlink.o: warning: objtool: __llvm_gcov_reset+0x1b94: 'naked' return found in RETHUNK build fs/fs_parser.o: warning: objtool: __llvm_gcov_reset+0x344: 'naked' return found in RETHUNK build drivers/acpi/debugfs.o: warning: objtool: __llvm_gcov_reset+0xb: 'naked' return found in RETHUNK build mm/pagewalk.o: warning: objtool: __llvm_gcov_reset+0x77f: 'naked' return found in RETHUNK build drivers/tty/serial/8250/8250_pnp.o: warning: objtool: __llvm_gcov_reset+0x231: 'naked' return found in RETHUNK build fs/init.o: warning: objtool: __llvm_gcov_reset+0x2f7: 'naked' return found in RETHUNK build drivers/gpu/drm/drm_fourcc.o: warning: objtool: __llvm_gcov_reset+0x1ce: 'naked' return found in RETHUNK build ... ``` > > > > > > > > Thanks for the report. I wonder if this might be a compiler bug; it > > > > seems like the {a|t}san.module_{c|d}tor functions are being emitted > > > > with ret instructions? > > > > > > > > If you have one of these builds lying around still, can you provide: > > > > > > > > $ llvm-objdump -dr --disassemble-symbols=tsan.module_ctor > > > > arch/x86/kernel/fpu/bugs.o > > > > > > Sure thing. > > > > > > With KASAN: > > > > > > $ llvm-objdump -r --disassemble-symbols=asan.module_ctor,asan.module_dtor build/arch/x86/kernel/fpu/bugs.o > > > > > > build/arch/x86/kernel/fpu/bugs.o: file format elf64-x86-64 > > > > > > Disassembly of section .text.asan.module_ctor: > > > > > > 0000000000000000 <asan.module_ctor>: > > > 0: be 01 00 00 00 movl $1, %esi > > > 5: 48 c7 c7 00 00 00 00 movq $0, %rdi > > > 0000000000000008: R_X86_64_32S .data > > > c: e8 00 00 00 00 callq 0x11 <asan.module_ctor+0x11> > > > 000000000000000d: R_X86_64_PLT32 __asan_register_globals-0x4 > > > 11: c3 retq > > > > As Nick said; this should be: 'jmp __x86_return_thunk', on those builds. > > https://github.com/llvm/llvm-project/issues/56514 > > -- > Thanks, > ~Nick Desaulniers -- Thanks, ~Nick Desaulniers ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y 2022-07-13 22:05 ` Nick Desaulniers @ 2022-07-14 0:31 ` Nick Desaulniers 0 siblings, 0 replies; 7+ messages in thread From: Nick Desaulniers @ 2022-07-14 0:31 UTC (permalink / raw) To: Nathan Chancellor; +Cc: Josh Poimboeuf, linux-kernel, llvm, Peter Zijlstra On Wed, Jul 13, 2022 at 3:05 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > > On Wed, Jul 13, 2022 at 9:42 AM Nick Desaulniers > <ndesaulniers@google.com> wrote: > > > > On Wed, Jul 13, 2022 at 9:25 AM Peter Zijlstra <peterz@infradead.org> wrote: > > > > > > On Wed, Jul 13, 2022 at 09:13:29AM -0700, Nathan Chancellor wrote: > > > > On Wed, Jul 13, 2022 at 09:01:58AM -0700, Nick Desaulniers wrote: > > > > > On Wed, Jul 13, 2022 at 8:48 AM Nathan Chancellor <nathan@kernel.org> wrote: > > > > > > > > > > > > Hi Josh and Peter, > > > > > > > > > > > > After commit 9bb2ec608a20 ("objtool: Update Retpoline validation") and > > > > > > commit f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs"), I > > > > > > see a spew of objtool warnings when building certain configurations with > > > > > > clang. Examples below, they appear to trigger in every single file. > > > > > > > > > > > > With x86_64_defconfig + CONFIG_KASAN=y: > > > > > > > > > > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > > arch/x86/ia32/audit.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > > init/version.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > > init/version.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > > arch/x86/kernel/platform-quirks.o: warning: objtool: asan.module_ctor+0x0: 'naked' return found in RETHUNK build > > > > > > init/calibrate.o: warning: objtool: asan.module_ctor+0x11: 'naked' return found in RETHUNK build > > > > > > init/calibrate.o: warning: objtool: asan.module_dtor+0x11: 'naked' return found in RETHUNK build > > > > > > > > > > > > With x86_64_defconfig + CONFIG_KCSAN=y: > > > > > > > > > > > > arch/x86/ia32/audit.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > > init/calibrate.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > > init/version.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > > arch/x86/kernel/fpu/bugs.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > > arch/x86/kernel/cpu/rdrand.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > > arch/x86/events/probe.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > > > > > arch/x86/kernel/apic/ipi.o: warning: objtool: tsan.module_ctor+0x5: 'naked' return found in RETHUNK build > > It's not just the sanitizers, `CONFIG_GCOV_KERNEL=y` + > `CONFIG_GCOV_PROFILE_ALL=y` also has this issue: > ``` > ... > drivers/base/platform.o: warning: objtool: __llvm_gcov_reset+0xa94: > 'naked' return found in RETHUNK build > net/core/netpoll.o: warning: objtool: __llvm_gcov_reset+0xde3: 'naked' > return found in RETHUNK build > net/netfilter/nf_conntrack_netlink.o: warning: objtool: > __llvm_gcov_reset+0x1b94: 'naked' return found in RETHUNK build > fs/fs_parser.o: warning: objtool: __llvm_gcov_reset+0x344: 'naked' > return found in RETHUNK build > drivers/acpi/debugfs.o: warning: objtool: __llvm_gcov_reset+0xb: > 'naked' return found in RETHUNK build > mm/pagewalk.o: warning: objtool: __llvm_gcov_reset+0x77f: 'naked' > return found in RETHUNK build > drivers/tty/serial/8250/8250_pnp.o: warning: objtool: > __llvm_gcov_reset+0x231: 'naked' return found in RETHUNK build > fs/init.o: warning: objtool: __llvm_gcov_reset+0x2f7: 'naked' return > found in RETHUNK build > drivers/gpu/drm/drm_fourcc.o: warning: objtool: > __llvm_gcov_reset+0x1ce: 'naked' return found in RETHUNK build > ... > ``` https://reviews.llvm.org/D129709 > > > > > > > > > > > Thanks for the report. I wonder if this might be a compiler bug; it > > > > > seems like the {a|t}san.module_{c|d}tor functions are being emitted > > > > > with ret instructions? > > > > > > > > > > If you have one of these builds lying around still, can you provide: > > > > > > > > > > $ llvm-objdump -dr --disassemble-symbols=tsan.module_ctor > > > > > arch/x86/kernel/fpu/bugs.o > > > > > > > > Sure thing. > > > > > > > > With KASAN: > > > > > > > > $ llvm-objdump -r --disassemble-symbols=asan.module_ctor,asan.module_dtor build/arch/x86/kernel/fpu/bugs.o > > > > > > > > build/arch/x86/kernel/fpu/bugs.o: file format elf64-x86-64 > > > > > > > > Disassembly of section .text.asan.module_ctor: > > > > > > > > 0000000000000000 <asan.module_ctor>: > > > > 0: be 01 00 00 00 movl $1, %esi > > > > 5: 48 c7 c7 00 00 00 00 movq $0, %rdi > > > > 0000000000000008: R_X86_64_32S .data > > > > c: e8 00 00 00 00 callq 0x11 <asan.module_ctor+0x11> > > > > 000000000000000d: R_X86_64_PLT32 __asan_register_globals-0x4 > > > > 11: c3 retq > > > > > > As Nick said; this should be: 'jmp __x86_return_thunk', on those builds. > > > > https://github.com/llvm/llvm-project/issues/56514 > > > > -- > > Thanks, > > ~Nick Desaulniers > > > > -- > Thanks, > ~Nick Desaulniers -- Thanks, ~Nick Desaulniers ^ permalink raw reply [flat|nested] 7+ messages in thread
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2022-07-13 15:47 objtool "'naked' return found in RETHUNK build" with clang + CONFIG_K{A,C}SAN=y Nathan Chancellor
2022-07-13 16:01 ` Nick Desaulniers
2022-07-13 16:13 ` Nathan Chancellor
2022-07-13 16:25 ` Peter Zijlstra
2022-07-13 16:42 ` Nick Desaulniers
2022-07-13 22:05 ` Nick Desaulniers
2022-07-14 0:31 ` Nick Desaulniers
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