* linux-next: build warnings after merge of the powerpc-objtool tree @ 2022-11-25 3:30 ` Stephen Rothwell 0 siblings, 0 replies; 10+ messages in thread From: Stephen Rothwell @ 2022-11-25 3:30 UTC (permalink / raw) To: Michael Ellerman, PowerPC Cc: Christophe Leroy, Sathvika Vasireddy, Linux Kernel Mailing List, Linux Next Mailing List [-- Attachment #1: Type: text/plain, Size: 458 bytes --] Hi all, After merging the powerpc-objtool tree, today's linux-next build (powerpc pseries_le_defconfig) produced these warnings: arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction I have no idea what started this (they may have been there yesterday). -- Cheers, Stephen Rothwell [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 488 bytes --] ^ permalink raw reply [flat|nested] 10+ messages in thread
* linux-next: build warnings after merge of the powerpc-objtool tree @ 2022-11-25 3:30 ` Stephen Rothwell 0 siblings, 0 replies; 10+ messages in thread From: Stephen Rothwell @ 2022-11-25 3:30 UTC (permalink / raw) To: Michael Ellerman, PowerPC Cc: Linux Next Mailing List, Sathvika Vasireddy, Linux Kernel Mailing List [-- Attachment #1: Type: text/plain, Size: 458 bytes --] Hi all, After merging the powerpc-objtool tree, today's linux-next build (powerpc pseries_le_defconfig) produced these warnings: arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction I have no idea what started this (they may have been there yesterday). -- Cheers, Stephen Rothwell [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 488 bytes --] ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: linux-next: build warnings after merge of the powerpc-objtool tree 2022-11-25 3:30 ` Stephen Rothwell @ 2022-11-29 15:13 ` Sathvika Vasireddy -1 siblings, 0 replies; 10+ messages in thread From: Sathvika Vasireddy @ 2022-11-29 15:13 UTC (permalink / raw) To: Stephen Rothwell, Michael Ellerman, PowerPC Cc: Christophe Leroy, Linux Kernel Mailing List, Linux Next Mailing List, Naveen N. Rao, Sathvika Vasireddy Hi all, On 25/11/22 09:00, Stephen Rothwell wrote: > Hi all, > > After merging the powerpc-objtool tree, today's linux-next build (powerpc > pseries_le_defconfig) produced these warnings: > > arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction > arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction > > I have no idea what started this (they may have been there yesterday). I was able to recreate the above mentioned warnings with pseries_le_defconfig and powernv_defconfig. The regression report also mentions a warning (https://lore.kernel.org/oe-kbuild-all/202211282102.QUr7HHrW-lkp@intel.com/) seen with arch/powerpc/kernel/kvm_emul.S assembly file. [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: kvm_template_end(): can't find starting instruction [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction The warnings [1] and [2] go away after adding 'nop' instruction. Below diff fixes it for me: diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S index cd4e7bc32609..ea4e3bd82f4f 100644 --- a/arch/powerpc/kernel/optprobes_head.S +++ b/arch/powerpc/kernel/optprobes_head.S @@ -134,3 +134,4 @@ optprobe_template_ret: .global optprobe_template_end optprobe_template_end: + nop diff --git a/arch/powerpc/kernel/kvm_emul.S b/arch/powerpc/kernel/kvm_emul.S index 7af6f8b50c5d..41fd664e3ba0 100644 --- a/arch/powerpc/kernel/kvm_emul.S +++ b/arch/powerpc/kernel/kvm_emul.S @@ -352,3 +352,4 @@ kvm_tmp_end: .global kvm_template_end kvm_template_end: + nop For warning [3], objtool is throwing can't find starting instruction warning because it finds that the symbol (end_first_256B) is zero sized, and such symbols are not added to the rbtree. I tried to fix it by adding a 'nop' instruction (pasted diff below), but that resulted in a kernel build failure. diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 874efd25cc45..d48850fe159f 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -192,6 +192,7 @@ __secondary_hold: EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0 #endif CLOSE_FIXED_SECTION(first_256B) +nop /* * On server, we include the exception vectors code here as it diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 26f8fef53c72..f7517d443e9b 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -3104,9 +3104,13 @@ __end_interrupts: DEFINE_FIXED_SYMBOL(__end_interrupts, virt_trampolines) CLOSE_FIXED_SECTION(real_vectors); +nop CLOSE_FIXED_SECTION(real_trampolines); +nop CLOSE_FIXED_SECTION(virt_vectors); +nop CLOSE_FIXED_SECTION(virt_trampolines); +nop USE_TEXT_SECTION() I'm not very sure on how to address this particular warning (arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction). Given that there are no calls to _mcount, one workaround is to skip objtool from running on arch/powerpc/kernel/head_64.o file. The below diff works for me: diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 9b6146056e48..9ef6a040d875 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -219,3 +219,5 @@ $(obj)/vdso64_wrapper.o : $(obj)/vdso/vdso64.so.dbg # for cleaning subdir- += vdso + +OBJECT_FILES_NON_STANDARD_head_64.o := y Thanks, Sathvika ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: linux-next: build warnings after merge of the powerpc-objtool tree @ 2022-11-29 15:13 ` Sathvika Vasireddy 0 siblings, 0 replies; 10+ messages in thread From: Sathvika Vasireddy @ 2022-11-29 15:13 UTC (permalink / raw) To: Stephen Rothwell, Michael Ellerman, PowerPC Cc: Naveen N. Rao, Linux Next Mailing List, Sathvika Vasireddy, Linux Kernel Mailing List Hi all, On 25/11/22 09:00, Stephen Rothwell wrote: > Hi all, > > After merging the powerpc-objtool tree, today's linux-next build (powerpc > pseries_le_defconfig) produced these warnings: > > arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction > arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction > > I have no idea what started this (they may have been there yesterday). I was able to recreate the above mentioned warnings with pseries_le_defconfig and powernv_defconfig. The regression report also mentions a warning (https://lore.kernel.org/oe-kbuild-all/202211282102.QUr7HHrW-lkp@intel.com/) seen with arch/powerpc/kernel/kvm_emul.S assembly file. [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: kvm_template_end(): can't find starting instruction [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction The warnings [1] and [2] go away after adding 'nop' instruction. Below diff fixes it for me: diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S index cd4e7bc32609..ea4e3bd82f4f 100644 --- a/arch/powerpc/kernel/optprobes_head.S +++ b/arch/powerpc/kernel/optprobes_head.S @@ -134,3 +134,4 @@ optprobe_template_ret: .global optprobe_template_end optprobe_template_end: + nop diff --git a/arch/powerpc/kernel/kvm_emul.S b/arch/powerpc/kernel/kvm_emul.S index 7af6f8b50c5d..41fd664e3ba0 100644 --- a/arch/powerpc/kernel/kvm_emul.S +++ b/arch/powerpc/kernel/kvm_emul.S @@ -352,3 +352,4 @@ kvm_tmp_end: .global kvm_template_end kvm_template_end: + nop For warning [3], objtool is throwing can't find starting instruction warning because it finds that the symbol (end_first_256B) is zero sized, and such symbols are not added to the rbtree. I tried to fix it by adding a 'nop' instruction (pasted diff below), but that resulted in a kernel build failure. diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 874efd25cc45..d48850fe159f 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -192,6 +192,7 @@ __secondary_hold: EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0 #endif CLOSE_FIXED_SECTION(first_256B) +nop /* * On server, we include the exception vectors code here as it diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 26f8fef53c72..f7517d443e9b 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -3104,9 +3104,13 @@ __end_interrupts: DEFINE_FIXED_SYMBOL(__end_interrupts, virt_trampolines) CLOSE_FIXED_SECTION(real_vectors); +nop CLOSE_FIXED_SECTION(real_trampolines); +nop CLOSE_FIXED_SECTION(virt_vectors); +nop CLOSE_FIXED_SECTION(virt_trampolines); +nop USE_TEXT_SECTION() I'm not very sure on how to address this particular warning (arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction). Given that there are no calls to _mcount, one workaround is to skip objtool from running on arch/powerpc/kernel/head_64.o file. The below diff works for me: diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 9b6146056e48..9ef6a040d875 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -219,3 +219,5 @@ $(obj)/vdso64_wrapper.o : $(obj)/vdso/vdso64.so.dbg # for cleaning subdir- += vdso + +OBJECT_FILES_NON_STANDARD_head_64.o := y Thanks, Sathvika ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: linux-next: build warnings after merge of the powerpc-objtool tree 2022-11-29 15:13 ` Sathvika Vasireddy @ 2022-11-29 15:28 ` Christophe Leroy -1 siblings, 0 replies; 10+ messages in thread From: Christophe Leroy @ 2022-11-29 15:28 UTC (permalink / raw) To: Sathvika Vasireddy, Stephen Rothwell, Michael Ellerman, PowerPC Cc: Linux Kernel Mailing List, Linux Next Mailing List, Naveen N. Rao Le 29/11/2022 à 16:13, Sathvika Vasireddy a écrit : > Hi all, > > On 25/11/22 09:00, Stephen Rothwell wrote: >> Hi all, >> >> After merging the powerpc-objtool tree, today's linux-next build (powerpc >> pseries_le_defconfig) produced these warnings: >> >> arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >> can't find starting instruction >> arch/powerpc/kernel/optprobes_head.o: warning: objtool: >> optprobe_template_end(): can't find starting instruction >> >> I have no idea what started this (they may have been there yesterday). > I was able to recreate the above mentioned warnings with > pseries_le_defconfig and powernv_defconfig. The regression report also > mentions a warning > (https://lore.kernel.org/oe-kbuild-all/202211282102.QUr7HHrW-lkp@intel.com/) seen with arch/powerpc/kernel/kvm_emul.S assembly file. > > [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: > optprobe_template_end(): can't find starting instruction > [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: > kvm_template_end(): can't find starting instruction > [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): > can't find starting instruction > > The warnings [1] and [2] go away after adding 'nop' instruction. Below > diff fixes it for me: You have to add NOPs just because those labels are at the end of the files. That's a bit odd. I think either we are missing some kind of flagging for the symbols, or objtool has a bug. In both cases, I'm not sure adding an artificial 'nop' is the solution. At least there should be a big hammer warning explaining why. > > diff --git a/arch/powerpc/kernel/optprobes_head.S > b/arch/powerpc/kernel/optprobes_head.S > index cd4e7bc32609..ea4e3bd82f4f 100644 > --- a/arch/powerpc/kernel/optprobes_head.S > +++ b/arch/powerpc/kernel/optprobes_head.S > @@ -134,3 +134,4 @@ optprobe_template_ret: > > .global optprobe_template_end > optprobe_template_end: > + nop > > diff --git a/arch/powerpc/kernel/kvm_emul.S > b/arch/powerpc/kernel/kvm_emul.S > index 7af6f8b50c5d..41fd664e3ba0 100644 > --- a/arch/powerpc/kernel/kvm_emul.S > +++ b/arch/powerpc/kernel/kvm_emul.S > @@ -352,3 +352,4 @@ kvm_tmp_end: > > .global kvm_template_end > kvm_template_end: > + nop > > For warning [3], objtool is throwing can't find starting instruction > warning because it finds that the symbol (end_first_256B) is zero sized, > and such symbols are not added to the rbtree. I tried to fix it by > adding a 'nop' instruction (pasted diff below), but that resulted in a > kernel build failure. What's the failure ? > > diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S > index 874efd25cc45..d48850fe159f 100644 > --- a/arch/powerpc/kernel/head_64.S > +++ b/arch/powerpc/kernel/head_64.S > @@ -192,6 +192,7 @@ __secondary_hold: > EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0 > #endif > CLOSE_FIXED_SECTION(first_256B) > +nop > > /* > * On server, we include the exception vectors code here as it > > diff --git a/arch/powerpc/kernel/exceptions-64s.S > b/arch/powerpc/kernel/exceptions-64s.S > index 26f8fef53c72..f7517d443e9b 100644 > --- a/arch/powerpc/kernel/exceptions-64s.S > +++ b/arch/powerpc/kernel/exceptions-64s.S > @@ -3104,9 +3104,13 @@ __end_interrupts: > DEFINE_FIXED_SYMBOL(__end_interrupts, virt_trampolines) > > CLOSE_FIXED_SECTION(real_vectors); > +nop > CLOSE_FIXED_SECTION(real_trampolines); > +nop > CLOSE_FIXED_SECTION(virt_vectors); > +nop > CLOSE_FIXED_SECTION(virt_trampolines); > +nop What are the NOPs after the CLOSE_FIXED_SECTION() ? You don't explain them, and I can't see any related warning in the warnings you show. > > USE_TEXT_SECTION() > > I'm not very sure on how to address this particular warning > (arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): > can't find starting instruction). Given that there are no calls to > _mcount, one workaround is to skip objtool from running on > arch/powerpc/kernel/head_64.o file. The below diff works for me: > > diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile > index 9b6146056e48..9ef6a040d875 100644 > --- a/arch/powerpc/kernel/Makefile > +++ b/arch/powerpc/kernel/Makefile > @@ -219,3 +219,5 @@ $(obj)/vdso64_wrapper.o : $(obj)/vdso/vdso64.so.dbg > > # for cleaning > subdir- += vdso > + > +OBJECT_FILES_NON_STANDARD_head_64.o := y Might be the solution, allthough I can't see other architectures doing that. > > > Thanks, > Sathvika Christophe ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: linux-next: build warnings after merge of the powerpc-objtool tree @ 2022-11-29 15:28 ` Christophe Leroy 0 siblings, 0 replies; 10+ messages in thread From: Christophe Leroy @ 2022-11-29 15:28 UTC (permalink / raw) To: Sathvika Vasireddy, Stephen Rothwell, Michael Ellerman, PowerPC Cc: Naveen N. Rao, Linux Next Mailing List, Linux Kernel Mailing List Le 29/11/2022 à 16:13, Sathvika Vasireddy a écrit : > Hi all, > > On 25/11/22 09:00, Stephen Rothwell wrote: >> Hi all, >> >> After merging the powerpc-objtool tree, today's linux-next build (powerpc >> pseries_le_defconfig) produced these warnings: >> >> arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >> can't find starting instruction >> arch/powerpc/kernel/optprobes_head.o: warning: objtool: >> optprobe_template_end(): can't find starting instruction >> >> I have no idea what started this (they may have been there yesterday). > I was able to recreate the above mentioned warnings with > pseries_le_defconfig and powernv_defconfig. The regression report also > mentions a warning > (https://lore.kernel.org/oe-kbuild-all/202211282102.QUr7HHrW-lkp@intel.com/) seen with arch/powerpc/kernel/kvm_emul.S assembly file. > > [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: > optprobe_template_end(): can't find starting instruction > [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: > kvm_template_end(): can't find starting instruction > [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): > can't find starting instruction > > The warnings [1] and [2] go away after adding 'nop' instruction. Below > diff fixes it for me: You have to add NOPs just because those labels are at the end of the files. That's a bit odd. I think either we are missing some kind of flagging for the symbols, or objtool has a bug. In both cases, I'm not sure adding an artificial 'nop' is the solution. At least there should be a big hammer warning explaining why. > > diff --git a/arch/powerpc/kernel/optprobes_head.S > b/arch/powerpc/kernel/optprobes_head.S > index cd4e7bc32609..ea4e3bd82f4f 100644 > --- a/arch/powerpc/kernel/optprobes_head.S > +++ b/arch/powerpc/kernel/optprobes_head.S > @@ -134,3 +134,4 @@ optprobe_template_ret: > > .global optprobe_template_end > optprobe_template_end: > + nop > > diff --git a/arch/powerpc/kernel/kvm_emul.S > b/arch/powerpc/kernel/kvm_emul.S > index 7af6f8b50c5d..41fd664e3ba0 100644 > --- a/arch/powerpc/kernel/kvm_emul.S > +++ b/arch/powerpc/kernel/kvm_emul.S > @@ -352,3 +352,4 @@ kvm_tmp_end: > > .global kvm_template_end > kvm_template_end: > + nop > > For warning [3], objtool is throwing can't find starting instruction > warning because it finds that the symbol (end_first_256B) is zero sized, > and such symbols are not added to the rbtree. I tried to fix it by > adding a 'nop' instruction (pasted diff below), but that resulted in a > kernel build failure. What's the failure ? > > diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S > index 874efd25cc45..d48850fe159f 100644 > --- a/arch/powerpc/kernel/head_64.S > +++ b/arch/powerpc/kernel/head_64.S > @@ -192,6 +192,7 @@ __secondary_hold: > EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0 > #endif > CLOSE_FIXED_SECTION(first_256B) > +nop > > /* > * On server, we include the exception vectors code here as it > > diff --git a/arch/powerpc/kernel/exceptions-64s.S > b/arch/powerpc/kernel/exceptions-64s.S > index 26f8fef53c72..f7517d443e9b 100644 > --- a/arch/powerpc/kernel/exceptions-64s.S > +++ b/arch/powerpc/kernel/exceptions-64s.S > @@ -3104,9 +3104,13 @@ __end_interrupts: > DEFINE_FIXED_SYMBOL(__end_interrupts, virt_trampolines) > > CLOSE_FIXED_SECTION(real_vectors); > +nop > CLOSE_FIXED_SECTION(real_trampolines); > +nop > CLOSE_FIXED_SECTION(virt_vectors); > +nop > CLOSE_FIXED_SECTION(virt_trampolines); > +nop What are the NOPs after the CLOSE_FIXED_SECTION() ? You don't explain them, and I can't see any related warning in the warnings you show. > > USE_TEXT_SECTION() > > I'm not very sure on how to address this particular warning > (arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): > can't find starting instruction). Given that there are no calls to > _mcount, one workaround is to skip objtool from running on > arch/powerpc/kernel/head_64.o file. The below diff works for me: > > diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile > index 9b6146056e48..9ef6a040d875 100644 > --- a/arch/powerpc/kernel/Makefile > +++ b/arch/powerpc/kernel/Makefile > @@ -219,3 +219,5 @@ $(obj)/vdso64_wrapper.o : $(obj)/vdso/vdso64.so.dbg > > # for cleaning > subdir- += vdso > + > +OBJECT_FILES_NON_STANDARD_head_64.o := y Might be the solution, allthough I can't see other architectures doing that. > > > Thanks, > Sathvika Christophe ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: linux-next: build warnings after merge of the powerpc-objtool tree 2022-11-29 15:28 ` Christophe Leroy @ 2022-11-30 11:51 ` Sathvika Vasireddy -1 siblings, 0 replies; 10+ messages in thread From: Sathvika Vasireddy @ 2022-11-30 11:51 UTC (permalink / raw) To: Christophe Leroy, Stephen Rothwell, Michael Ellerman, PowerPC, peterz Cc: Linux Kernel Mailing List, Linux Next Mailing List, Naveen N. Rao On 29/11/22 20:58, Christophe Leroy wrote: > > Le 29/11/2022 à 16:13, Sathvika Vasireddy a écrit : >> Hi all, >> >> On 25/11/22 09:00, Stephen Rothwell wrote: >>> Hi all, >>> >>> After merging the powerpc-objtool tree, today's linux-next build (powerpc >>> pseries_le_defconfig) produced these warnings: >>> >>> arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >>> can't find starting instruction >>> arch/powerpc/kernel/optprobes_head.o: warning: objtool: >>> optprobe_template_end(): can't find starting instruction >>> >>> I have no idea what started this (they may have been there yesterday). >> I was able to recreate the above mentioned warnings with >> pseries_le_defconfig and powernv_defconfig. The regression report also >> mentions a warning >> (https://lore.kernel.org/oe-kbuild-all/202211282102.QUr7HHrW-lkp@intel.com/) seen with arch/powerpc/kernel/kvm_emul.S assembly file. >> >> [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: >> optprobe_template_end(): can't find starting instruction >> [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: >> kvm_template_end(): can't find starting instruction >> [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >> can't find starting instruction >> >> The warnings [1] and [2] go away after adding 'nop' instruction. Below >> diff fixes it for me: > You have to add NOPs just because those labels are at the end of the > files. That's a bit odd. > I think either we are missing some kind of flagging for the symbols, or > objtool has a bug. In both cases, I'm not sure adding an artificial > 'nop' is the solution. At least there should be a big hammer warning > explaining why. I don't see these warnings with powerpc/topic/objtool branch. However, they are seen with linux-next master branch. Commit dbcdbdfdf137b49144204571f1a5e5dc01b8aaad objtool: Rework instruction -> symbol mapping in linux-next is resulting in objtool can't find starting instruction warnings on powerpc. Reverting this particular hunk (pasted below), resolves it and we don't see the problem anymore. @@ -427,7 +427,10 @@ static int decode_instructions(struct objtool_file *file) } list_for_each_entry(func, &sec->symbol_list, list) { - if (func->type != STT_FUNC || func->alias != func) + if (func->type != STT_NOTYPE && func->type != STT_FUNC) + continue; + + if (func->return_thunk || func->alias != func) continue; if (!find_insn(file, sec, func->offset)) { Peterz, can we ignore STT_NOTYPE symbols? >> diff --git a/arch/powerpc/kernel/optprobes_head.S >> b/arch/powerpc/kernel/optprobes_head.S >> index cd4e7bc32609..ea4e3bd82f4f 100644 >> --- a/arch/powerpc/kernel/optprobes_head.S >> +++ b/arch/powerpc/kernel/optprobes_head.S >> @@ -134,3 +134,4 @@ optprobe_template_ret: >> >> .global optprobe_template_end >> optprobe_template_end: >> + nop >> >> diff --git a/arch/powerpc/kernel/kvm_emul.S >> b/arch/powerpc/kernel/kvm_emul.S >> index 7af6f8b50c5d..41fd664e3ba0 100644 >> --- a/arch/powerpc/kernel/kvm_emul.S >> +++ b/arch/powerpc/kernel/kvm_emul.S >> @@ -352,3 +352,4 @@ kvm_tmp_end: >> >> .global kvm_template_end >> kvm_template_end: >> + nop >> >> For warning [3], objtool is throwing can't find starting instruction >> warning because it finds that the symbol (end_first_256B) is zero sized, >> and such symbols are not added to the rbtree. I tried to fix it by >> adding a 'nop' instruction (pasted diff below), but that resulted in a >> kernel build failure. > What's the failure ? > > >> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S >> index 874efd25cc45..d48850fe159f 100644 >> --- a/arch/powerpc/kernel/head_64.S >> +++ b/arch/powerpc/kernel/head_64.S >> @@ -192,6 +192,7 @@ __secondary_hold: >> EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0 >> #endif >> CLOSE_FIXED_SECTION(first_256B) >> +nop >> >> /* >> * On server, we include the exception vectors code here as it >> >> diff --git a/arch/powerpc/kernel/exceptions-64s.S >> b/arch/powerpc/kernel/exceptions-64s.S >> index 26f8fef53c72..f7517d443e9b 100644 >> --- a/arch/powerpc/kernel/exceptions-64s.S >> +++ b/arch/powerpc/kernel/exceptions-64s.S >> @@ -3104,9 +3104,13 @@ __end_interrupts: >> DEFINE_FIXED_SYMBOL(__end_interrupts, virt_trampolines) >> >> CLOSE_FIXED_SECTION(real_vectors); >> +nop >> CLOSE_FIXED_SECTION(real_trampolines); >> +nop >> CLOSE_FIXED_SECTION(virt_vectors); >> +nop >> CLOSE_FIXED_SECTION(virt_trampolines); >> +nop > What are the NOPs after the CLOSE_FIXED_SECTION() ? You don't explain > them, and I can't see any related warning in the warnings you show. > > After fixing arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction warning, objtool started showing more warnings in the same file. Below is the list of warnings: arch/powerpc/kernel/head_64.o: warning: objtool: end_real_vectors(): can't find starting instruction arch/powerpc/kernel/head_64.o: warning: objtool: end_real_trampolines(): can't find starting instruction arch/powerpc/kernel/head_64.o: warning: objtool: end_virt_vectors(): can't find starting instruction arch/powerpc/kernel/head_64.o: warning: objtool: end_virt_trampolines(): can't find starting instruction Thanks, Sathvika ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: linux-next: build warnings after merge of the powerpc-objtool tree @ 2022-11-30 11:51 ` Sathvika Vasireddy 0 siblings, 0 replies; 10+ messages in thread From: Sathvika Vasireddy @ 2022-11-30 11:51 UTC (permalink / raw) To: Christophe Leroy, Stephen Rothwell, Michael Ellerman, PowerPC, peterz Cc: Naveen N. Rao, Linux Next Mailing List, Linux Kernel Mailing List On 29/11/22 20:58, Christophe Leroy wrote: > > Le 29/11/2022 à 16:13, Sathvika Vasireddy a écrit : >> Hi all, >> >> On 25/11/22 09:00, Stephen Rothwell wrote: >>> Hi all, >>> >>> After merging the powerpc-objtool tree, today's linux-next build (powerpc >>> pseries_le_defconfig) produced these warnings: >>> >>> arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >>> can't find starting instruction >>> arch/powerpc/kernel/optprobes_head.o: warning: objtool: >>> optprobe_template_end(): can't find starting instruction >>> >>> I have no idea what started this (they may have been there yesterday). >> I was able to recreate the above mentioned warnings with >> pseries_le_defconfig and powernv_defconfig. The regression report also >> mentions a warning >> (https://lore.kernel.org/oe-kbuild-all/202211282102.QUr7HHrW-lkp@intel.com/) seen with arch/powerpc/kernel/kvm_emul.S assembly file. >> >> [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: >> optprobe_template_end(): can't find starting instruction >> [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: >> kvm_template_end(): can't find starting instruction >> [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >> can't find starting instruction >> >> The warnings [1] and [2] go away after adding 'nop' instruction. Below >> diff fixes it for me: > You have to add NOPs just because those labels are at the end of the > files. That's a bit odd. > I think either we are missing some kind of flagging for the symbols, or > objtool has a bug. In both cases, I'm not sure adding an artificial > 'nop' is the solution. At least there should be a big hammer warning > explaining why. I don't see these warnings with powerpc/topic/objtool branch. However, they are seen with linux-next master branch. Commit dbcdbdfdf137b49144204571f1a5e5dc01b8aaad objtool: Rework instruction -> symbol mapping in linux-next is resulting in objtool can't find starting instruction warnings on powerpc. Reverting this particular hunk (pasted below), resolves it and we don't see the problem anymore. @@ -427,7 +427,10 @@ static int decode_instructions(struct objtool_file *file) } list_for_each_entry(func, &sec->symbol_list, list) { - if (func->type != STT_FUNC || func->alias != func) + if (func->type != STT_NOTYPE && func->type != STT_FUNC) + continue; + + if (func->return_thunk || func->alias != func) continue; if (!find_insn(file, sec, func->offset)) { Peterz, can we ignore STT_NOTYPE symbols? >> diff --git a/arch/powerpc/kernel/optprobes_head.S >> b/arch/powerpc/kernel/optprobes_head.S >> index cd4e7bc32609..ea4e3bd82f4f 100644 >> --- a/arch/powerpc/kernel/optprobes_head.S >> +++ b/arch/powerpc/kernel/optprobes_head.S >> @@ -134,3 +134,4 @@ optprobe_template_ret: >> >> .global optprobe_template_end >> optprobe_template_end: >> + nop >> >> diff --git a/arch/powerpc/kernel/kvm_emul.S >> b/arch/powerpc/kernel/kvm_emul.S >> index 7af6f8b50c5d..41fd664e3ba0 100644 >> --- a/arch/powerpc/kernel/kvm_emul.S >> +++ b/arch/powerpc/kernel/kvm_emul.S >> @@ -352,3 +352,4 @@ kvm_tmp_end: >> >> .global kvm_template_end >> kvm_template_end: >> + nop >> >> For warning [3], objtool is throwing can't find starting instruction >> warning because it finds that the symbol (end_first_256B) is zero sized, >> and such symbols are not added to the rbtree. I tried to fix it by >> adding a 'nop' instruction (pasted diff below), but that resulted in a >> kernel build failure. > What's the failure ? > > >> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S >> index 874efd25cc45..d48850fe159f 100644 >> --- a/arch/powerpc/kernel/head_64.S >> +++ b/arch/powerpc/kernel/head_64.S >> @@ -192,6 +192,7 @@ __secondary_hold: >> EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0 >> #endif >> CLOSE_FIXED_SECTION(first_256B) >> +nop >> >> /* >> * On server, we include the exception vectors code here as it >> >> diff --git a/arch/powerpc/kernel/exceptions-64s.S >> b/arch/powerpc/kernel/exceptions-64s.S >> index 26f8fef53c72..f7517d443e9b 100644 >> --- a/arch/powerpc/kernel/exceptions-64s.S >> +++ b/arch/powerpc/kernel/exceptions-64s.S >> @@ -3104,9 +3104,13 @@ __end_interrupts: >> DEFINE_FIXED_SYMBOL(__end_interrupts, virt_trampolines) >> >> CLOSE_FIXED_SECTION(real_vectors); >> +nop >> CLOSE_FIXED_SECTION(real_trampolines); >> +nop >> CLOSE_FIXED_SECTION(virt_vectors); >> +nop >> CLOSE_FIXED_SECTION(virt_trampolines); >> +nop > What are the NOPs after the CLOSE_FIXED_SECTION() ? You don't explain > them, and I can't see any related warning in the warnings you show. > > After fixing arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction warning, objtool started showing more warnings in the same file. Below is the list of warnings: arch/powerpc/kernel/head_64.o: warning: objtool: end_real_vectors(): can't find starting instruction arch/powerpc/kernel/head_64.o: warning: objtool: end_real_trampolines(): can't find starting instruction arch/powerpc/kernel/head_64.o: warning: objtool: end_virt_vectors(): can't find starting instruction arch/powerpc/kernel/head_64.o: warning: objtool: end_virt_trampolines(): can't find starting instruction Thanks, Sathvika ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: linux-next: build warnings after merge of the powerpc-objtool tree 2022-11-30 11:51 ` Sathvika Vasireddy @ 2022-12-06 10:14 ` Naveen N. Rao -1 siblings, 0 replies; 10+ messages in thread From: Naveen N. Rao @ 2022-12-06 10:14 UTC (permalink / raw) To: Christophe Leroy, PowerPC, Michael Ellerman, peterz, Stephen Rothwell, Sathvika Vasireddy Cc: Linux Kernel Mailing List, Linux Next Mailing List Sathvika Vasireddy wrote: > > On 29/11/22 20:58, Christophe Leroy wrote: >> >> Le 29/11/2022 à 16:13, Sathvika Vasireddy a écrit : >>> Hi all, >>> >>> On 25/11/22 09:00, Stephen Rothwell wrote: >>>> Hi all, >>>> >>>> After merging the powerpc-objtool tree, today's linux-next build (powerpc >>>> pseries_le_defconfig) produced these warnings: >>>> >>>> arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >>>> can't find starting instruction >>>> arch/powerpc/kernel/optprobes_head.o: warning: objtool: >>>> optprobe_template_end(): can't find starting instruction >>>> >>>> I have no idea what started this (they may have been there yesterday). >>> I was able to recreate the above mentioned warnings with >>> pseries_le_defconfig and powernv_defconfig. The regression report also >>> mentions a warning >>> (https://lore.kernel.org/oe-kbuild-all/202211282102.QUr7HHrW-lkp@intel.com/) seen with arch/powerpc/kernel/kvm_emul.S assembly file. >>> >>> [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: >>> optprobe_template_end(): can't find starting instruction >>> [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: >>> kvm_template_end(): can't find starting instruction >>> [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >>> can't find starting instruction >>> >>> The warnings [1] and [2] go away after adding 'nop' instruction. Below >>> diff fixes it for me: >> You have to add NOPs just because those labels are at the end of the >> files. That's a bit odd. >> I think either we are missing some kind of flagging for the symbols, or >> objtool has a bug. In both cases, I'm not sure adding an artificial >> 'nop' is the solution. At least there should be a big hammer warning >> explaining why. The problem looks to be that commit dbcdbdfdf137b4 ("objtool: Rework instruction -> symbol mapping"), which was referenced by Sathvika below, changes how STT_NOTYPE symbols are handled. In the files throwing that warning, there are labels either at the very end of the file, or at the end of a section with no subsequent instruction. Before that commit, we didn't used to expect an instruction for STT_NOTYPE symbols. > > I don't see these warnings with powerpc/topic/objtool branch. However, > they are seen with linux-next master branch. > Commit dbcdbdfdf137b49144204571f1a5e5dc01b8aaad objtool: Rework > instruction -> symbol mapping in linux-next is resulting in objtool > can't find starting instruction warnings on powerpc. > > Reverting this particular hunk (pasted below), resolves it and we don't > see the problem anymore. > > @@ -427,7 +427,10 @@ static int decode_instructions(struct objtool_file > *file) > } > > list_for_each_entry(func, &sec->symbol_list, list) { > - if (func->type != STT_FUNC || func->alias != func) > + if (func->type != STT_NOTYPE && func->type != > STT_FUNC) > + continue; > + > + if (func->return_thunk || func->alias != func) > continue; > > if (!find_insn(file, sec, func->offset)) { We are currently bailing out if find_insn() there fails. Should we instead just continue by not setting insn->sym? @@ -430,11 +430,8 @@ static int decode_instructions(struct objtool_file *file) if (func->return_thunk || func->alias != func) continue; - if (!find_insn(file, sec, func->offset)) { - WARN("%s(): can't find starting instruction", - func->name); - return -1; - } + if (!find_insn(file, sec, func->offset)) + continue; sym_for_each_insn(file, func, insn) { insn->sym = func; - Naveen ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: linux-next: build warnings after merge of the powerpc-objtool tree @ 2022-12-06 10:14 ` Naveen N. Rao 0 siblings, 0 replies; 10+ messages in thread From: Naveen N. Rao @ 2022-12-06 10:14 UTC (permalink / raw) To: Christophe Leroy, PowerPC, Michael Ellerman, peterz, Stephen Rothwell, Sathvika Vasireddy Cc: Linux Next Mailing List, Linux Kernel Mailing List Sathvika Vasireddy wrote: > > On 29/11/22 20:58, Christophe Leroy wrote: >> >> Le 29/11/2022 à 16:13, Sathvika Vasireddy a écrit : >>> Hi all, >>> >>> On 25/11/22 09:00, Stephen Rothwell wrote: >>>> Hi all, >>>> >>>> After merging the powerpc-objtool tree, today's linux-next build (powerpc >>>> pseries_le_defconfig) produced these warnings: >>>> >>>> arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >>>> can't find starting instruction >>>> arch/powerpc/kernel/optprobes_head.o: warning: objtool: >>>> optprobe_template_end(): can't find starting instruction >>>> >>>> I have no idea what started this (they may have been there yesterday). >>> I was able to recreate the above mentioned warnings with >>> pseries_le_defconfig and powernv_defconfig. The regression report also >>> mentions a warning >>> (https://lore.kernel.org/oe-kbuild-all/202211282102.QUr7HHrW-lkp@intel.com/) seen with arch/powerpc/kernel/kvm_emul.S assembly file. >>> >>> [1] arch/powerpc/kernel/optprobes_head.o: warning: objtool: >>> optprobe_template_end(): can't find starting instruction >>> [2] arch/powerpc/kernel/kvm_emul.o: warning: objtool: >>> kvm_template_end(): can't find starting instruction >>> [3] arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): >>> can't find starting instruction >>> >>> The warnings [1] and [2] go away after adding 'nop' instruction. Below >>> diff fixes it for me: >> You have to add NOPs just because those labels are at the end of the >> files. That's a bit odd. >> I think either we are missing some kind of flagging for the symbols, or >> objtool has a bug. In both cases, I'm not sure adding an artificial >> 'nop' is the solution. At least there should be a big hammer warning >> explaining why. The problem looks to be that commit dbcdbdfdf137b4 ("objtool: Rework instruction -> symbol mapping"), which was referenced by Sathvika below, changes how STT_NOTYPE symbols are handled. In the files throwing that warning, there are labels either at the very end of the file, or at the end of a section with no subsequent instruction. Before that commit, we didn't used to expect an instruction for STT_NOTYPE symbols. > > I don't see these warnings with powerpc/topic/objtool branch. However, > they are seen with linux-next master branch. > Commit dbcdbdfdf137b49144204571f1a5e5dc01b8aaad objtool: Rework > instruction -> symbol mapping in linux-next is resulting in objtool > can't find starting instruction warnings on powerpc. > > Reverting this particular hunk (pasted below), resolves it and we don't > see the problem anymore. > > @@ -427,7 +427,10 @@ static int decode_instructions(struct objtool_file > *file) > } > > list_for_each_entry(func, &sec->symbol_list, list) { > - if (func->type != STT_FUNC || func->alias != func) > + if (func->type != STT_NOTYPE && func->type != > STT_FUNC) > + continue; > + > + if (func->return_thunk || func->alias != func) > continue; > > if (!find_insn(file, sec, func->offset)) { We are currently bailing out if find_insn() there fails. Should we instead just continue by not setting insn->sym? @@ -430,11 +430,8 @@ static int decode_instructions(struct objtool_file *file) if (func->return_thunk || func->alias != func) continue; - if (!find_insn(file, sec, func->offset)) { - WARN("%s(): can't find starting instruction", - func->name); - return -1; - } + if (!find_insn(file, sec, func->offset)) + continue; sym_for_each_insn(file, func, insn) { insn->sym = func; - Naveen ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2022-12-06 10:15 UTC | newest] Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-11-25 3:30 linux-next: build warnings after merge of the powerpc-objtool tree Stephen Rothwell 2022-11-25 3:30 ` Stephen Rothwell 2022-11-29 15:13 ` Sathvika Vasireddy 2022-11-29 15:13 ` Sathvika Vasireddy 2022-11-29 15:28 ` Christophe Leroy 2022-11-29 15:28 ` Christophe Leroy 2022-11-30 11:51 ` Sathvika Vasireddy 2022-11-30 11:51 ` Sathvika Vasireddy 2022-12-06 10:14 ` Naveen N. Rao 2022-12-06 10:14 ` Naveen N. Rao
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