From: Fangrui Song <maskray@google.com> To: Nick Desaulniers <ndesaulniers@google.com> Cc: Kees Cook <keescook@chromium.org>, Thomas Gleixner <tglx@linutronix.de>, Will Deacon <will@kernel.org>, Catalin Marinas <catalin.marinas@arm.com>, Mark Rutland <mark.rutland@arm.com>, Ard Biesheuvel <ardb@kernel.org>, Peter Collingbourne <pcc@google.com>, James Morse <james.morse@arm.com>, Borislav Petkov <bp@suse.de>, Ingo Molnar <mingo@redhat.com>, Russell King <linux@armlinux.org.uk>, Masahiro Yamada <masahiroy@kernel.org>, Arvind Sankar <nivedita@alum.mit.edu>, Nathan Chancellor <natechancellor@gmail.com>, Arnd Bergmann <arnd@arndb.de>, "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>, clang-built-linux <clang-built-linux@googlegroups.com>, linux-arch <linux-arch@vger.kernel.org>, linux-efi <linux-efi@vger.kernel.org>, Linux ARM <linux-arm-kernel@lists.infradead.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v5 23/36] arm/build: Explicitly keep .ARM.attributes sections Date: Mon, 17 Aug 2020 15:06:29 -0700 [thread overview] Message-ID: <20200817220629.3pkabegeedomsaaz@google.com> (raw) In-Reply-To: <CAKwvOdn11z+iFQZC54JvQHC=NFX1FsoRMw2a-2P=5sQ6FKwbnw@mail.gmail.com> On 2020-08-03, 'Nick Desaulniers' via Clang Built Linux wrote: >On Fri, Jul 31, 2020 at 4:18 PM Kees Cook <keescook@chromium.org> wrote: >> >> In preparation for adding --orphan-handling=warn, explicitly keep the >> .ARM.attributes section by expanding the existing ELF_DETAILS macro into >> ARM_DETAILS. >> >> Suggested-by: Nick Desaulniers <ndesaulniers@google.com> >> Link: https://lore.kernel.org/lkml/CAKwvOdk-racgq5pxsoGS6Vtifbtrk5fmkmnoLxrQMaOvV0nPWw@mail.gmail.com/ >> Signed-off-by: Kees Cook <keescook@chromium.org> >> --- >> arch/arm/include/asm/vmlinux.lds.h | 4 ++++ >> arch/arm/kernel/vmlinux-xip.lds.S | 2 +- >> arch/arm/kernel/vmlinux.lds.S | 2 +- >> 3 files changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm/include/asm/vmlinux.lds.h b/arch/arm/include/asm/vmlinux.lds.h >> index a08f4301b718..c4af5182ab48 100644 >> --- a/arch/arm/include/asm/vmlinux.lds.h >> +++ b/arch/arm/include/asm/vmlinux.lds.h >> @@ -52,6 +52,10 @@ >> ARM_MMU_DISCARD(*(__ex_table)) \ >> COMMON_DISCARDS >> >> +#define ARM_DETAILS \ >> + ELF_DETAILS \ >> + .ARM.attributes 0 : { *(.ARM.attributes) } > >I had to look up what the `0` meant: >https://sourceware.org/binutils/docs/ld/Output-Section-Attributes.html#Output-Section-Attributes >mentions it's an "address" and >https://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_chapter/ld_3.html#SEC21 >mentions it as "start" (an address). >Unless we need those, can we drop them? (Sorry for the resulting churn >that would cause). I think the NO_LOAD stuff makes more sense, but >I'm curious if the kernel checks for that. NOLOAD means SHT_NOBITS (usually SHF_ALLOC). .ARM.attributes is a non-SHF_ALLOC section. An explicit 0 (output section address) is good - GNU ld's internal linker scripts (ld --verbose output) use 0 for such non-SHF_ALLOC sections. Without the 0, the section may get a non-zero address, which is not wrong - but probably does not look well. See https://reviews.llvm.org/D85867 for details. Reviewed-by: Fangrui Song <maskray@google.com> >> + >> #define ARM_STUBS_TEXT \ >> *(.gnu.warning) \ >> *(.glue_7) \ >> diff --git a/arch/arm/kernel/vmlinux-xip.lds.S b/arch/arm/kernel/vmlinux-xip.lds.S >> index 904c31fa20ed..57fcbf55f913 100644 >> --- a/arch/arm/kernel/vmlinux-xip.lds.S >> +++ b/arch/arm/kernel/vmlinux-xip.lds.S >> @@ -150,7 +150,7 @@ SECTIONS >> _end = .; >> >> STABS_DEBUG >> - ELF_DETAILS >> + ARM_DETAILS >> } >> >> /* >> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S >> index bb950c896a67..1d3d3b599635 100644 >> --- a/arch/arm/kernel/vmlinux.lds.S >> +++ b/arch/arm/kernel/vmlinux.lds.S >> @@ -149,7 +149,7 @@ SECTIONS >> _end = .; >> >> STABS_DEBUG >> - ELF_DETAILS >> + ARM_DETAILS >> } >> >> #ifdef CONFIG_STRICT_KERNEL_RWX >> -- >> 2.25.1 >>
WARNING: multiple messages have this Message-ID (diff)
From: Fangrui Song <maskray@google.com> To: Nick Desaulniers <ndesaulniers@google.com> Cc: Mark Rutland <mark.rutland@arm.com>, linux-arch <linux-arch@vger.kernel.org>, linux-efi <linux-efi@vger.kernel.org>, Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>, Peter Collingbourne <pcc@google.com>, Catalin Marinas <catalin.marinas@arm.com>, Masahiro Yamada <masahiroy@kernel.org>, "maintainer:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" <x86@kernel.org>, Russell King <linux@armlinux.org.uk>, LKML <linux-kernel@vger.kernel.org>, Nathan Chancellor <natechancellor@gmail.com>, clang-built-linux <clang-built-linux@googlegroups.com>, Arvind Sankar <nivedita@alum.mit.edu>, Ingo Molnar <mingo@redhat.com>, James Morse <james.morse@arm.com>, Thomas Gleixner <tglx@linutronix.de>, Borislav Petkov <bp@suse.de>, Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>, Linux ARM <linux-arm-kernel@lists.infradead.org> Subject: Re: [PATCH v5 23/36] arm/build: Explicitly keep .ARM.attributes sections Date: Mon, 17 Aug 2020 15:06:29 -0700 [thread overview] Message-ID: <20200817220629.3pkabegeedomsaaz@google.com> (raw) In-Reply-To: <CAKwvOdn11z+iFQZC54JvQHC=NFX1FsoRMw2a-2P=5sQ6FKwbnw@mail.gmail.com> On 2020-08-03, 'Nick Desaulniers' via Clang Built Linux wrote: >On Fri, Jul 31, 2020 at 4:18 PM Kees Cook <keescook@chromium.org> wrote: >> >> In preparation for adding --orphan-handling=warn, explicitly keep the >> .ARM.attributes section by expanding the existing ELF_DETAILS macro into >> ARM_DETAILS. >> >> Suggested-by: Nick Desaulniers <ndesaulniers@google.com> >> Link: https://lore.kernel.org/lkml/CAKwvOdk-racgq5pxsoGS6Vtifbtrk5fmkmnoLxrQMaOvV0nPWw@mail.gmail.com/ >> Signed-off-by: Kees Cook <keescook@chromium.org> >> --- >> arch/arm/include/asm/vmlinux.lds.h | 4 ++++ >> arch/arm/kernel/vmlinux-xip.lds.S | 2 +- >> arch/arm/kernel/vmlinux.lds.S | 2 +- >> 3 files changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm/include/asm/vmlinux.lds.h b/arch/arm/include/asm/vmlinux.lds.h >> index a08f4301b718..c4af5182ab48 100644 >> --- a/arch/arm/include/asm/vmlinux.lds.h >> +++ b/arch/arm/include/asm/vmlinux.lds.h >> @@ -52,6 +52,10 @@ >> ARM_MMU_DISCARD(*(__ex_table)) \ >> COMMON_DISCARDS >> >> +#define ARM_DETAILS \ >> + ELF_DETAILS \ >> + .ARM.attributes 0 : { *(.ARM.attributes) } > >I had to look up what the `0` meant: >https://sourceware.org/binutils/docs/ld/Output-Section-Attributes.html#Output-Section-Attributes >mentions it's an "address" and >https://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_chapter/ld_3.html#SEC21 >mentions it as "start" (an address). >Unless we need those, can we drop them? (Sorry for the resulting churn >that would cause). I think the NO_LOAD stuff makes more sense, but >I'm curious if the kernel checks for that. NOLOAD means SHT_NOBITS (usually SHF_ALLOC). .ARM.attributes is a non-SHF_ALLOC section. An explicit 0 (output section address) is good - GNU ld's internal linker scripts (ld --verbose output) use 0 for such non-SHF_ALLOC sections. Without the 0, the section may get a non-zero address, which is not wrong - but probably does not look well. See https://reviews.llvm.org/D85867 for details. Reviewed-by: Fangrui Song <maskray@google.com> >> + >> #define ARM_STUBS_TEXT \ >> *(.gnu.warning) \ >> *(.glue_7) \ >> diff --git a/arch/arm/kernel/vmlinux-xip.lds.S b/arch/arm/kernel/vmlinux-xip.lds.S >> index 904c31fa20ed..57fcbf55f913 100644 >> --- a/arch/arm/kernel/vmlinux-xip.lds.S >> +++ b/arch/arm/kernel/vmlinux-xip.lds.S >> @@ -150,7 +150,7 @@ SECTIONS >> _end = .; >> >> STABS_DEBUG >> - ELF_DETAILS >> + ARM_DETAILS >> } >> >> /* >> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S >> index bb950c896a67..1d3d3b599635 100644 >> --- a/arch/arm/kernel/vmlinux.lds.S >> +++ b/arch/arm/kernel/vmlinux.lds.S >> @@ -149,7 +149,7 @@ SECTIONS >> _end = .; >> >> STABS_DEBUG >> - ELF_DETAILS >> + ARM_DETAILS >> } >> >> #ifdef CONFIG_STRICT_KERNEL_RWX >> -- >> 2.25.1 >> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-08-17 22:06 UTC|newest] Thread overview: 152+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-31 23:07 [PATCH v5 00/36] Warn on orphan section placement Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` [PATCH v5 01/36] x86/boot/compressed: Move .got.plt entries out of the .got section Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-08-14 15:23 ` [tip: x86/boot] " tip-bot2 for Ard Biesheuvel 2020-07-31 23:07 ` [PATCH v5 02/36] x86/boot/compressed: Force hidden visibility for all symbol references Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-08-14 15:23 ` [tip: x86/boot] " tip-bot2 for Ard Biesheuvel 2020-07-31 23:07 ` [PATCH v5 03/36] x86/boot/compressed: Get rid of GOT fixup code Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-08-14 15:23 ` [tip: x86/boot] " tip-bot2 for Ard Biesheuvel 2020-07-31 23:07 ` [PATCH v5 04/36] x86/boot: Add .text.* to setup.ld Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-08-14 15:23 ` [tip: x86/boot] " tip-bot2 for Arvind Sankar 2020-07-31 23:07 ` [PATCH v5 05/36] x86/boot: Remove run-time relocations from .head.text code Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:42 ` Nick Desaulniers 2020-07-31 23:42 ` Nick Desaulniers 2020-07-31 23:42 ` Nick Desaulniers 2020-08-14 15:23 ` [tip: x86/boot] " tip-bot2 for Arvind Sankar 2020-07-31 23:07 ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32,64}.S Kees Cook 2020-07-31 23:07 ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32, 64}.S Kees Cook 2020-07-31 23:07 ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32,64}.S Kees Cook 2020-08-07 18:12 ` Nick Desaulniers 2020-08-07 18:12 ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32, 64}.S Nick Desaulniers 2020-08-07 20:20 ` [PATCH v5 06/36] x86/boot: Remove run-time relocations from head_{32,64}.S Arvind Sankar 2020-08-07 20:20 ` Arvind Sankar 2020-08-14 15:23 ` [tip: x86/boot] " tip-bot2 for Arvind Sankar 2020-07-31 23:07 ` [PATCH v5 07/36] x86/boot: Check that there are no run-time relocations Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-08-14 15:23 ` [tip: x86/boot] " tip-bot2 for Arvind Sankar 2020-07-31 23:07 ` [PATCH v5 08/36] vmlinux.lds.h: Create COMMON_DISCARDS Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` [PATCH v5 09/36] vmlinux.lds.h: Add .gnu.version* to COMMON_DISCARDS Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` [PATCH v5 10/36] vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` [PATCH v5 11/36] vmlinux.lds.h: Split ELF_DETAILS from STABS_DEBUG Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` [PATCH v5 12/36] vmlinux.lds.h: Add .symtab, .strtab, and .shstrtab to ELF_DETAILS Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` [PATCH v5 13/36] vmlinux.lds.h: add PGO and AutoFDO input sections Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-08-01 3:51 ` Arvind Sankar 2020-08-01 3:51 ` Arvind Sankar 2020-08-01 3:51 ` Arvind Sankar 2020-08-01 6:18 ` Kees Cook 2020-08-01 6:18 ` Kees Cook 2020-08-01 6:18 ` Kees Cook 2020-08-01 17:27 ` Arvind Sankar 2020-08-01 17:27 ` Arvind Sankar 2020-08-01 17:27 ` Arvind Sankar 2020-08-03 19:05 ` Andi Kleen 2020-08-03 19:05 ` Andi Kleen 2020-08-03 19:05 ` Andi Kleen 2020-08-03 20:15 ` Arvind Sankar 2020-08-03 20:15 ` Arvind Sankar 2020-08-03 20:15 ` Arvind Sankar 2020-08-04 1:19 ` Fāng-ruì Sòng 2020-08-04 1:19 ` Fāng-ruì Sòng 2020-08-04 1:19 ` Fāng-ruì Sòng 2020-08-04 4:45 ` Andi Kleen 2020-08-04 4:45 ` Andi Kleen 2020-08-04 4:45 ` Andi Kleen 2020-08-04 5:32 ` Fāng-ruì Sòng 2020-08-04 5:32 ` Fāng-ruì Sòng 2020-08-04 5:32 ` Fāng-ruì Sòng 2020-08-04 16:06 ` Arvind Sankar 2020-08-04 16:06 ` Arvind Sankar 2020-08-04 16:06 ` Arvind Sankar 2020-08-21 19:18 ` Kees Cook 2020-08-21 19:18 ` Kees Cook 2020-08-06 1:24 ` Sasha Levin 2020-08-06 1:28 ` Nick Desaulniers 2020-08-19 23:56 ` Sasha Levin 2020-07-31 23:07 ` [PATCH v5 14/36] efi/libstub: Disable -mbranch-protection Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:07 ` [PATCH v5 15/36] arm64/mm: Remove needless section quotes Kees Cook 2020-07-31 23:07 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 16/36] arm64/kernel: Remove needless Call Frame Information annotations Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 17/36] arm64/build: Remove .eh_frame* sections due to unwind tables Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 18/36] arm64/build: Use common DISCARDS in linker script Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 19/36] arm64/build: Add missing DWARF sections Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 20/36] arm64/build: Assert for unwanted sections Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 21/36] arm64/build: Warn on orphan section placement Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 22/36] arm/build: Refactor linker script headers Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 23/36] arm/build: Explicitly keep .ARM.attributes sections Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-08-03 19:02 ` Nick Desaulniers 2020-08-03 19:02 ` Nick Desaulniers 2020-08-03 19:02 ` Nick Desaulniers 2020-08-17 22:06 ` Fangrui Song [this message] 2020-08-17 22:06 ` Fangrui Song 2020-07-31 23:08 ` [PATCH v5 24/36] arm/build: Add missing sections Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 25/36] arm/build: Warn on orphan section placement Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 26/36] arm/boot: Handle all sections explicitly Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 27/36] arm/boot: Warn on orphan section placement Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 28/36] x86/asm: Avoid generating unused kprobe sections Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 29/36] x86/build: Enforce an empty .got.plt section Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-08-01 2:12 ` Arvind Sankar 2020-08-01 2:12 ` Arvind Sankar 2020-08-01 5:32 ` Kees Cook 2020-08-01 5:32 ` Kees Cook 2020-08-21 17:49 ` Kees Cook 2020-08-21 17:49 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 30/36] x86/build: Assert for unwanted sections Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 31/36] x86/build: Warn on orphan section placement Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 32/36] x86/boot/compressed: Reorganize zero-size section asserts Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-08-01 1:47 ` Arvind Sankar 2020-08-01 1:47 ` Arvind Sankar 2020-08-01 2:53 ` Arvind Sankar 2020-08-01 2:53 ` Arvind Sankar 2020-08-01 5:36 ` Kees Cook 2020-08-01 5:36 ` Kees Cook 2020-08-01 17:12 ` Arvind Sankar 2020-08-01 17:12 ` Arvind Sankar 2020-08-21 18:24 ` Kees Cook 2020-08-21 18:24 ` Kees Cook 2020-08-01 5:35 ` Kees Cook 2020-08-01 5:35 ` Kees Cook 2020-08-01 17:00 ` Arvind Sankar 2020-08-01 17:00 ` Arvind Sankar 2020-08-21 18:19 ` Kees Cook 2020-08-21 18:19 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 33/36] x86/boot/compressed: Remove, discard, or assert for unwanted sections Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 34/36] x86/boot/compressed: Add missing debugging sections to output Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 35/36] x86/boot/compressed: Warn on orphan section placement Kees Cook 2020-07-31 23:08 ` Kees Cook 2020-07-31 23:08 ` [PATCH v5 36/36] arm/build: Assert for unwanted sections Kees Cook 2020-07-31 23:08 ` Kees Cook
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