* [PATCH v2] x86_64: Add "-m elf_i386" when linking i386 object files. [not found] <CAKwvOdnr1=Q=mL-P2icMTP8do3CVH+KF8564fKmpK_OshKxKwg@mail.gmail.com> @ 2019-01-11 19:14 ` Tri Vo 2019-01-11 19:27 ` Nick Desaulniers 0 siblings, 1 reply; 5+ messages in thread From: Tri Vo @ 2019-01-11 19:14 UTC (permalink / raw) To: x86, tglx, mingo, bp, hpa Cc: grimar, dima, morbo, ndesaulniers, matz, ruiu, linux-kernel, Tri Vo From: George Rimar <grimar@accesssoftek.com> Linux kernel uses OUTPUT_FORMAT in it's linker scripts. Most of the time -m option is passed to the linker with correct architecture, but sometimes (at least for x86_64) the -m option contradicts OUTPUT_FORMAT directive. Specifically, arch/x86/boot and arch/x86/realmode/rm modules have i386 object files, but are linked with -m elf_x86_64 linker flag when building for x86_64. "man ld" doesn't explicitly state any tie-breakers between -m and OUTPUT_FORMAT. BFD and Gold linkers override -m value with OUTPUT_FORMAT. But LLVM lld has a different behavior. When supplied with contradicting -m and OUTPUT_FORMAT values it fails with the following error message: ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64 Suggested fix: just add correct -m after incorrect one (it overrides it), so the linker invocation looks like this: ld -m elf_x86_64 -z max-page-size=0x200000 -m elf_i386 --emit-relocs -T realmode.lds header.o trampoline_64.o stack.o reboot.o -o realmode.elf This is not a functional change for GNU ld, because (although not explicitly documented) it already overrides -m EMULATION with OUTPUT_FORMAT. Tested by building x86_64 kernel with GNU gcc/ld toolchain and booting it in QEMU. Suggested-by: Dmitry Golovin <dima@golovin.in> Signed-off-by: Georgii Rymar <grimar@accesssoftek.com> Signed-off-by: Tri Vo <trong@android.com> Tested-by: Tri Vo <trong@android.com> --- arch/x86/boot/Makefile | 2 +- arch/x86/realmode/rm/Makefile | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 9b5adae9cc40..e2839b5c246c 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE AFLAGS_header.o += -I$(objtree)/$(obj) $(obj)/header.o: $(obj)/zoffset.h -LDFLAGS_setup.elf := -T +LDFLAGS_setup.elf := -m elf_i386 -T $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE $(call if_changed,ld) diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile index 4463fa72db94..96cb20de08af 100644 --- a/arch/x86/realmode/rm/Makefile +++ b/arch/x86/realmode/rm/Makefile @@ -47,7 +47,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE targets += realmode.lds $(obj)/realmode.lds: $(obj)/pasyms.h -LDFLAGS_realmode.elf := --emit-relocs -T +LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj) targets += realmode.elf -- 2.20.1.97.g81188d93c3-goog ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] x86_64: Add "-m elf_i386" when linking i386 object files. 2019-01-11 19:14 ` [PATCH v2] x86_64: Add "-m elf_i386" when linking i386 object files Tri Vo @ 2019-01-11 19:27 ` Nick Desaulniers 2019-01-11 20:10 ` [PATCH v3] " Tri Vo 0 siblings, 1 reply; 5+ messages in thread From: Nick Desaulniers @ 2019-01-11 19:27 UTC (permalink / raw) To: Tri Vo Cc: x86, Thomas Gleixner, mingo, Borislav Petkov, hpa, George Rimar, Dmitry Golovin, Bill Wendling, Michael Matz, Rui Ueyama, LKML On Fri, Jan 11, 2019 at 11:14 AM Tri Vo <trong@android.com> wrote: > > From: George Rimar <grimar@accesssoftek.com> > > Linux kernel uses OUTPUT_FORMAT in it's linker scripts. Most of the time > -m option is passed to the linker with correct architecture, but > sometimes (at least for x86_64) the -m option contradicts OUTPUT_FORMAT > directive. Specifically, arch/x86/boot and arch/x86/realmode/rm modules > have i386 object files, but are linked with -m elf_x86_64 linker flag > when building for x86_64. > > "man ld" doesn't explicitly state any tie-breakers between -m and > OUTPUT_FORMAT. BFD and Gold linkers override -m value with > OUTPUT_FORMAT. But LLVM lld has a different behavior. When supplied with > contradicting -m and OUTPUT_FORMAT values it fails with the following > error message: > > ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64 > > Suggested fix: just add correct -m after incorrect one (it overrides > it), so the linker invocation looks like this: ld -m elf_x86_64 -z > max-page-size=0x200000 -m elf_i386 --emit-relocs -T realmode.lds > header.o trampoline_64.o stack.o reboot.o -o realmode.elf > > This is not a functional change for GNU ld, because (although not > explicitly documented) it already overrides -m EMULATION with > OUTPUT_FORMAT. > > Tested by building x86_64 kernel with GNU gcc/ld toolchain and booting > it in QEMU. > > Suggested-by: Dmitry Golovin <dima@golovin.in> > Signed-off-by: Georgii Rymar <grimar@accesssoftek.com> misspelled, and you may carry forward my tested by tag from v1. > Signed-off-by: Tri Vo <trong@android.com> > Tested-by: Tri Vo <trong@android.com> > --- So when making a change, you can put any text below this `---` delimiter. For LKML, it's common practice to put something like: v1 -> v2: updated commit message That helps code review so reviewers know what to expect "inter-diff" when eyeballing patch files. Internally when using gerrit, it will highlight inter-version diffs (ie. what changed between v2 and v3 of a patch), but since we do things the hard way on LKML, this can help a lot. After `git format-patch ...`, I usually add such a comment to the patch file in vim before sending. > arch/x86/boot/Makefile | 2 +- > arch/x86/realmode/rm/Makefile | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile > index 9b5adae9cc40..e2839b5c246c 100644 > --- a/arch/x86/boot/Makefile > +++ b/arch/x86/boot/Makefile > @@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE > AFLAGS_header.o += -I$(objtree)/$(obj) > $(obj)/header.o: $(obj)/zoffset.h > > -LDFLAGS_setup.elf := -T > +LDFLAGS_setup.elf := -m elf_i386 -T > $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE > $(call if_changed,ld) > > diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile > index 4463fa72db94..96cb20de08af 100644 > --- a/arch/x86/realmode/rm/Makefile > +++ b/arch/x86/realmode/rm/Makefile > @@ -47,7 +47,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE > targets += realmode.lds > $(obj)/realmode.lds: $(obj)/pasyms.h > > -LDFLAGS_realmode.elf := --emit-relocs -T > +LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T > CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj) > > targets += realmode.elf > -- > 2.20.1.97.g81188d93c3-goog > -- Thanks, ~Nick Desaulniers ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v3] x86_64: Add "-m elf_i386" when linking i386 object files. 2019-01-11 19:27 ` Nick Desaulniers @ 2019-01-11 20:10 ` Tri Vo 2019-01-12 8:39 ` [tip:x86/build] x86/build: Specify elf_i386 linker emulation explicitly for i386 objects tip-bot for George Rimar 2019-01-12 10:00 ` [PATCH v3] x86_64: Add "-m elf_i386" when linking i386 object files George Rimar 0 siblings, 2 replies; 5+ messages in thread From: Tri Vo @ 2019-01-11 20:10 UTC (permalink / raw) To: x86, tglx, mingo, bp, hpa Cc: grimar, dima, morbo, ndesaulniers, matz, ruiu, linux-kernel, Tri Vo From: George Rimar <grimar@accesssoftek.com> Linux kernel uses OUTPUT_FORMAT in it's linker scripts. Most of the time -m option is passed to the linker with correct architecture, but sometimes (at least for x86_64) the -m option contradicts OUTPUT_FORMAT directive. Specifically, arch/x86/boot and arch/x86/realmode/rm modules have i386 object files, but are linked with -m elf_x86_64 linker flag when building for x86_64. "man ld" doesn't explicitly state any tie-breakers between -m and OUTPUT_FORMAT. BFD and Gold linkers override -m value with OUTPUT_FORMAT. But LLVM lld has a different behavior. When supplied with contradicting -m and OUTPUT_FORMAT values it fails with the following error message: ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64 Suggested fix: just add correct -m after incorrect one (it overrides it), so the linker invocation looks like this: ld -m elf_x86_64 -z max-page-size=0x200000 -m elf_i386 --emit-relocs -T realmode.lds header.o trampoline_64.o stack.o reboot.o -o realmode.elf This is not a functional change for GNU ld, because (although not explicitly documented) it already overrides -m EMULATION with OUTPUT_FORMAT. Tested by building x86_64 kernel with GNU gcc/ld toolchain and booting it in QEMU. Suggested-by: Dmitry Golovin <dima@golovin.in> Signed-off-by: George Rimar <grimar@accesssoftek.com> Signed-off-by: Tri Vo <trong@android.com> Tested-by: Tri Vo <trong@android.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> --- v2: updated commit message to clarify that ld documentation is ambiguous w.r.t -m vs OUTPUT_FORMAT behavior. v3: fixed/added SOB and "Tested-by" fields. arch/x86/boot/Makefile | 2 +- arch/x86/realmode/rm/Makefile | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 9b5adae9cc40..e2839b5c246c 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE AFLAGS_header.o += -I$(objtree)/$(obj) $(obj)/header.o: $(obj)/zoffset.h -LDFLAGS_setup.elf := -T +LDFLAGS_setup.elf := -m elf_i386 -T $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE $(call if_changed,ld) diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile index 4463fa72db94..96cb20de08af 100644 --- a/arch/x86/realmode/rm/Makefile +++ b/arch/x86/realmode/rm/Makefile @@ -47,7 +47,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE targets += realmode.lds $(obj)/realmode.lds: $(obj)/pasyms.h -LDFLAGS_realmode.elf := --emit-relocs -T +LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj) targets += realmode.elf -- 2.20.1.97.g81188d93c3-goog ^ permalink raw reply related [flat|nested] 5+ messages in thread
* [tip:x86/build] x86/build: Specify elf_i386 linker emulation explicitly for i386 objects 2019-01-11 20:10 ` [PATCH v3] " Tri Vo @ 2019-01-12 8:39 ` tip-bot for George Rimar 2019-01-12 10:00 ` [PATCH v3] x86_64: Add "-m elf_i386" when linking i386 object files George Rimar 1 sibling, 0 replies; 5+ messages in thread From: tip-bot for George Rimar @ 2019-01-12 8:39 UTC (permalink / raw) To: linux-tip-commits Cc: linux-kernel, mingo, hpa, bp, trong, tglx, ndesaulniers, mingo, grimar, matz, x86, dima Commit-ID: 927185c124d62a9a4d35878d7f6d432a166b74e3 Gitweb: https://git.kernel.org/tip/927185c124d62a9a4d35878d7f6d432a166b74e3 Author: George Rimar <grimar@accesssoftek.com> AuthorDate: Fri, 11 Jan 2019 12:10:12 -0800 Committer: Borislav Petkov <bp@suse.de> CommitDate: Sat, 12 Jan 2019 00:11:39 +0100 x86/build: Specify elf_i386 linker emulation explicitly for i386 objects The kernel uses the OUTPUT_FORMAT linker script command in it's linker scripts. Most of the time, the -m option is passed to the linker with correct architecture, but sometimes (at least for x86_64) the -m option contradicts the OUTPUT_FORMAT directive. Specifically, arch/x86/boot and arch/x86/realmode/rm produce i386 object files, but are linked with the -m elf_x86_64 linker flag when building for x86_64. The GNU linker manpage doesn't explicitly state any tie-breakers between -m and OUTPUT_FORMAT. But with BFD and Gold linkers, OUTPUT_FORMAT overrides the emulation value specified with the -m option. LLVM lld has a different behavior, however. When supplied with contradicting -m and OUTPUT_FORMAT values it fails with the following error message: ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64 Therefore, just add the correct -m after the incorrect one (it overrides it), so the linker invocation looks like this: ld -m elf_x86_64 -z max-page-size=0x200000 -m elf_i386 --emit-relocs -T \ realmode.lds header.o trampoline_64.o stack.o reboot.o -o realmode.elf This is not a functional change for GNU ld, because (although not explicitly documented) OUTPUT_FORMAT overrides -m EMULATION. Tested by building x86_64 kernel with GNU gcc/ld toolchain and booting it in QEMU. [ bp: massage and clarify text. ] Suggested-by: Dmitry Golovin <dima@golovin.in> Signed-off-by: George Rimar <grimar@accesssoftek.com> Signed-off-by: Tri Vo <trong@android.com> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Tri Vo <trong@android.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Michael Matz <matz@suse.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: morbo@google.com Cc: ndesaulniers@google.com Cc: ruiu@google.com Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190111201012.71210-1-trong@android.com --- arch/x86/boot/Makefile | 2 +- arch/x86/realmode/rm/Makefile | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 9b5adae9cc40..e2839b5c246c 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE AFLAGS_header.o += -I$(objtree)/$(obj) $(obj)/header.o: $(obj)/zoffset.h -LDFLAGS_setup.elf := -T +LDFLAGS_setup.elf := -m elf_i386 -T $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE $(call if_changed,ld) diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile index 4463fa72db94..96cb20de08af 100644 --- a/arch/x86/realmode/rm/Makefile +++ b/arch/x86/realmode/rm/Makefile @@ -47,7 +47,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE targets += realmode.lds $(obj)/realmode.lds: $(obj)/pasyms.h -LDFLAGS_realmode.elf := --emit-relocs -T +LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj) targets += realmode.elf ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v3] x86_64: Add "-m elf_i386" when linking i386 object files. 2019-01-11 20:10 ` [PATCH v3] " Tri Vo 2019-01-12 8:39 ` [tip:x86/build] x86/build: Specify elf_i386 linker emulation explicitly for i386 objects tip-bot for George Rimar @ 2019-01-12 10:00 ` George Rimar 1 sibling, 0 replies; 5+ messages in thread From: George Rimar @ 2019-01-12 10:00 UTC (permalink / raw) To: Tri Vo, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com Cc: dima@golovin.in, morbo@google.com, ndesaulniers@google.com, matz@suse.de, ruiu@google.com, linux-kernel@vger.kernel.org Signed-off-by: George Rimar <grimar@accesssoftek.com> Best regards, George | Developer | Access Softek, Inc ________________________________________ От: Tri Vo <trong@android.com> Отправлено: 11 января 2019 г. 23:10 Кому: x86@kernel.org; tglx@linutronix.de; mingo@redhat.com; bp@alien8.de; hpa@zytor.com Копия: George Rimar; dima@golovin.in; morbo@google.com; ndesaulniers@google.com; matz@suse.de; ruiu@google.com; linux-kernel@vger.kernel.org; Tri Vo Тема: [PATCH v3] x86_64: Add "-m elf_i386" when linking i386 object files. CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. If you suspect potential phishing or spam email, report it to ReportSpam@accesssoftek.com From: George Rimar <grimar@accesssoftek.com> Linux kernel uses OUTPUT_FORMAT in it's linker scripts. Most of the time -m option is passed to the linker with correct architecture, but sometimes (at least for x86_64) the -m option contradicts OUTPUT_FORMAT directive. Specifically, arch/x86/boot and arch/x86/realmode/rm modules have i386 object files, but are linked with -m elf_x86_64 linker flag when building for x86_64. "man ld" doesn't explicitly state any tie-breakers between -m and OUTPUT_FORMAT. BFD and Gold linkers override -m value with OUTPUT_FORMAT. But LLVM lld has a different behavior. When supplied with contradicting -m and OUTPUT_FORMAT values it fails with the following error message: ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64 Suggested fix: just add correct -m after incorrect one (it overrides it), so the linker invocation looks like this: ld -m elf_x86_64 -z max-page-size=0x200000 -m elf_i386 --emit-relocs -T realmode.lds header.o trampoline_64.o stack.o reboot.o -o realmode.elf This is not a functional change for GNU ld, because (although not explicitly documented) it already overrides -m EMULATION with OUTPUT_FORMAT. Tested by building x86_64 kernel with GNU gcc/ld toolchain and booting it in QEMU. Suggested-by: Dmitry Golovin <dima@golovin.in> Signed-off-by: George Rimar <grimar@accesssoftek.com> Signed-off-by: Tri Vo <trong@android.com> Tested-by: Tri Vo <trong@android.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> --- v2: updated commit message to clarify that ld documentation is ambiguous w.r.t -m vs OUTPUT_FORMAT behavior. v3: fixed/added SOB and "Tested-by" fields. arch/x86/boot/Makefile | 2 +- arch/x86/realmode/rm/Makefile | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 9b5adae9cc40..e2839b5c246c 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE AFLAGS_header.o += -I$(objtree)/$(obj) $(obj)/header.o: $(obj)/zoffset.h -LDFLAGS_setup.elf := -T +LDFLAGS_setup.elf := -m elf_i386 -T $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE $(call if_changed,ld) diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile index 4463fa72db94..96cb20de08af 100644 --- a/arch/x86/realmode/rm/Makefile +++ b/arch/x86/realmode/rm/Makefile @@ -47,7 +47,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE targets += realmode.lds $(obj)/realmode.lds: $(obj)/pasyms.h -LDFLAGS_realmode.elf := --emit-relocs -T +LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj) targets += realmode.elf -- 2.20.1.97.g81188d93c3-goog ^ permalink raw reply related [flat|nested] 5+ messages in thread
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[not found] <CAKwvOdnr1=Q=mL-P2icMTP8do3CVH+KF8564fKmpK_OshKxKwg@mail.gmail.com>
2019-01-11 19:14 ` [PATCH v2] x86_64: Add "-m elf_i386" when linking i386 object files Tri Vo
2019-01-11 19:27 ` Nick Desaulniers
2019-01-11 20:10 ` [PATCH v3] " Tri Vo
2019-01-12 8:39 ` [tip:x86/build] x86/build: Specify elf_i386 linker emulation explicitly for i386 objects tip-bot for George Rimar
2019-01-12 10:00 ` [PATCH v3] x86_64: Add "-m elf_i386" when linking i386 object files George Rimar
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