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From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>,
	"H.J. Lu" <hjl.tools@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Peter Collingbourne <pcc@google.com>,
	James Morse <james.morse@arm.com>, Arnd Bergmann <arnd@arndb.de>,
	Masahiro Yamada <masahiroy@kernel.org>,
	x86@kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-arch@vger.kernel.org, linux-kbuild@vger.kernel.org,
	clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org
Subject: [PATCH 3/9] x86/build: Warn on orphan section placement
Date: Thu, 27 Feb 2020 16:22:38 -0800	[thread overview]
Message-ID: <20200228002244.15240-4-keescook@chromium.org> (raw)
In-Reply-To: <20200228002244.15240-1-keescook@chromium.org>

We don't want to depend on the linker's orphan section placement
heuristics as these can vary between linkers, and may change between
versions. All sections need to be explicitly named in the linker
script.

Discards the unused rela, plt, and got sections that are not needed
in the final vmlinux, and enable orphan section warnings.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/x86/Makefile             | 4 ++++
 arch/x86/kernel/vmlinux.lds.S | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 94df0868804b..b2c8becadce5 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -51,6 +51,10 @@ ifdef CONFIG_X86_NEED_RELOCS
         LDFLAGS_vmlinux := --emit-relocs --discard-none
 endif
 
+# We never want expected sections to be placed heuristically by the
+# linker. All sections should be explicitly named in the linker script.
+LDFLAGS_vmlinux += --orphan-handling=warn
+
 #
 # Prevent GCC from generating any FP code by mistake.
 #
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 5cab3a29adcb..1e345f302a46 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -412,6 +412,12 @@ SECTIONS
 	DWARF_DEBUG
 
 	DISCARDS
+	/DISCARD/ : {
+		*(.rela.*) *(.rela_*)
+		*(.rel.*) *(.rel_*)
+		*(.got) *(.got.*)
+		*(.igot.*) *(.iplt)
+	}
 }
 
 
-- 
2.20.1


WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@suse.de>
Cc: Mark Rutland <mark.rutland@arm.com>,
	"H.J. Lu" <hjl.tools@gmail.com>,
	Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
	linux-kbuild@vger.kernel.org,
	Peter Collingbourne <pcc@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	x86@kernel.org, Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	James Morse <james.morse@arm.com>,
	linux-arch@vger.kernel.org, Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/9] x86/build: Warn on orphan section placement
Date: Thu, 27 Feb 2020 16:22:38 -0800	[thread overview]
Message-ID: <20200228002244.15240-4-keescook@chromium.org> (raw)
In-Reply-To: <20200228002244.15240-1-keescook@chromium.org>

We don't want to depend on the linker's orphan section placement
heuristics as these can vary between linkers, and may change between
versions. All sections need to be explicitly named in the linker
script.

Discards the unused rela, plt, and got sections that are not needed
in the final vmlinux, and enable orphan section warnings.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/x86/Makefile             | 4 ++++
 arch/x86/kernel/vmlinux.lds.S | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 94df0868804b..b2c8becadce5 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -51,6 +51,10 @@ ifdef CONFIG_X86_NEED_RELOCS
         LDFLAGS_vmlinux := --emit-relocs --discard-none
 endif
 
+# We never want expected sections to be placed heuristically by the
+# linker. All sections should be explicitly named in the linker script.
+LDFLAGS_vmlinux += --orphan-handling=warn
+
 #
 # Prevent GCC from generating any FP code by mistake.
 #
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 5cab3a29adcb..1e345f302a46 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -412,6 +412,12 @@ SECTIONS
 	DWARF_DEBUG
 
 	DISCARDS
+	/DISCARD/ : {
+		*(.rela.*) *(.rela_*)
+		*(.rel.*) *(.rel_*)
+		*(.got) *(.got.*)
+		*(.igot.*) *(.iplt)
+	}
 }
 
 
-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2020-02-28  0:22 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-28  0:22 [PATCH 0/9] Enable orphan section warning Kees Cook
2020-02-28  0:22 ` Kees Cook
2020-02-28  0:22 ` [PATCH 1/9] scripts/link-vmlinux.sh: Delay orphan handling warnings until final link Kees Cook
2020-02-28  0:22   ` Kees Cook
2020-03-20  2:47   ` Nicholas Piggin
2020-03-20  2:47     ` Nicholas Piggin
2020-03-20 18:24     ` Kees Cook
2020-03-20 18:24       ` Kees Cook
2020-03-22  9:16       ` Nicholas Piggin
2020-03-22  9:16         ` Nicholas Piggin
2020-03-22 16:00         ` Kees Cook
2020-03-22 16:00           ` Kees Cook
2020-02-28  0:22 ` [PATCH 2/9] vmlinux.lds.h: Add .gnu.version* to DISCARDS Kees Cook
2020-02-28  0:22   ` Kees Cook
2020-02-28  0:22 ` Kees Cook [this message]
2020-02-28  0:22   ` [PATCH 3/9] x86/build: Warn on orphan section placement Kees Cook
2020-02-28  0:22 ` [PATCH 4/9] x86/boot: " Kees Cook
2020-02-28  0:22   ` Kees Cook
2020-02-28  0:22 ` [PATCH 5/9] Add RUNTIME_DISCARD_EXIT to generic DISCARDS Kees Cook
2020-02-28  0:22   ` Kees Cook
2020-02-28  0:22 ` [PATCH 6/9] arm64/build: Use common DISCARDS in linker script Kees Cook
2020-02-28  0:22   ` Kees Cook
2020-03-17 21:52   ` Will Deacon
2020-03-17 21:52     ` Will Deacon
2020-02-28  0:22 ` [PATCH 7/9] arm64/build: Warn on orphan section placement Kees Cook
2020-02-28  0:22   ` Kees Cook
2020-03-17 21:56   ` Will Deacon
2020-03-17 21:56     ` Will Deacon
2020-03-17 23:01     ` Kees Cook
2020-03-17 23:01       ` Kees Cook
2020-03-17 23:10       ` Nick Desaulniers
2020-03-17 23:10         ` Nick Desaulniers
2020-02-28  0:22 ` [PATCH 8/9] arm/build: " Kees Cook
2020-02-28  0:22   ` Kees Cook
2020-02-28  0:22 ` [PATCH 9/9] arm/boot: " Kees Cook
2020-02-28  0:22   ` Kees Cook
2020-02-28  6:51 ` [PATCH 0/9] Enable orphan section warning Sedat Dilek
2020-02-28  6:51   ` Sedat Dilek
2020-03-03  4:32   ` Kees Cook
2020-03-03  4:32     ` Kees Cook
2020-04-02 16:20 ` Sedat Dilek
2020-04-02 16:20   ` Sedat Dilek
2020-04-02 17:26   ` Kees Cook
2020-04-02 17:26     ` Kees Cook
2020-04-05 11:15     ` Sedat Dilek
2020-04-05 11:15       ` Sedat Dilek

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