135 lines
4.5 KiB
Diff
135 lines
4.5 KiB
Diff
From 25d3cf21987c752240df03c050593621ed2bd3a3 Mon Sep 17 00:00:00 2001
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From: Laura Abbott <labbott@redhat.com>
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Date: Tue, 3 Jul 2018 15:50:14 -0700
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Subject: [PATCHv6 1/4] kbuild: Add build salt to the kernel and modules
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To: Andy Lutomirski <luto@kernel.org>
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To: mjw@fedoraproject.org
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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To: H. J. Lu <hjl.tools@gmail.com>
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Cc: X86 ML <x86@kernel.org>
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Cc: linux-kernel@vger.kernel.org
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To: Masahiro Yamada <yamada.masahiro@socionext.com>
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Cc: Nick Clifton <nickc@redhat.com>
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Cc: Cary Coutant <ccoutant@gmail.com>
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Cc: linux-kbuild@vger.kernel.org
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Cc: linuxppc-dev@lists.ozlabs.org
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To: Michael Ellerman <mpe@ellerman.id.au>
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To: Catalin Marinas <catalin.marinas@arm.com>
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To: Will Deacon <will.deacon@arm.com>
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Cc: linux-arm-kernel@lists.infradead.org
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In Fedora, the debug information is packaged separately (foo-debuginfo) and
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can be installed separately. There's been a long standing issue where only
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one version of a debuginfo info package can be installed at a time. There's
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been an effort for Fedora for parallel debuginfo to rectify this problem.
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Part of the requirement to allow parallel debuginfo to work is that build ids
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are unique between builds. The existing upstream rpm implementation ensures
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this by re-calculating the build-id using the version and release as a
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seed. This doesn't work 100% for the kernel because of the vDSO which is
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its own binary and doesn't get updated when embedded.
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Fix this by adding some data in an ELF note for both the kernel and modules.
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The data is controlled via a Kconfig option so distributions can set it
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to an appropriate value to ensure uniqueness between builds.
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Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Signed-off-by: Laura Abbott <labbott@redhat.com>
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---
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v6: Added more detail to the commit text about why exactly this feature
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is useful. Default string now ""
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---
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include/linux/build-salt.h | 20 ++++++++++++++++++++
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init/Kconfig | 9 +++++++++
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init/version.c | 3 +++
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scripts/mod/modpost.c | 3 +++
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4 files changed, 35 insertions(+)
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create mode 100644 include/linux/build-salt.h
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diff --git a/include/linux/build-salt.h b/include/linux/build-salt.h
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new file mode 100644
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index 000000000000..bb007bd05e7a
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--- /dev/null
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+++ b/include/linux/build-salt.h
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@@ -0,0 +1,20 @@
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+#ifndef __BUILD_SALT_H
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+#define __BUILD_SALT_H
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+
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+#include <linux/elfnote.h>
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+
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+#define LINUX_ELFNOTE_BUILD_SALT 0x100
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+
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+#ifdef __ASSEMBLER__
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+
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+#define BUILD_SALT \
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+ ELFNOTE(Linux, LINUX_ELFNOTE_BUILD_SALT, .asciz CONFIG_BUILD_SALT)
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+
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+#else
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+
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+#define BUILD_SALT \
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+ ELFNOTE32("Linux", LINUX_ELFNOTE_BUILD_SALT, CONFIG_BUILD_SALT)
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+
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+#endif
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+
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+#endif /* __BUILD_SALT_H */
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diff --git a/init/Kconfig b/init/Kconfig
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index 041f3a022122..d39b31484c52 100644
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--- a/init/Kconfig
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+++ b/init/Kconfig
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@@ -107,6 +107,15 @@ config LOCALVERSION_AUTO
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which is done within the script "scripts/setlocalversion".)
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+config BUILD_SALT
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+ string "Build ID Salt"
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+ default ""
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+ help
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+ The build ID is used to link binaries and their debug info. Setting
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+ this option will use the value in the calculation of the build id.
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+ This is mostly useful for distributions which want to ensure the
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+ build is unique between builds. It's safe to leave the default.
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+
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config HAVE_KERNEL_GZIP
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bool
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diff --git a/init/version.c b/init/version.c
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index bfb4e3f4955e..ef4012ec4375 100644
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--- a/init/version.c
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+++ b/init/version.c
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@@ -7,6 +7,7 @@
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*/
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#include <generated/compile.h>
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+#include <linux/build-salt.h>
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#include <linux/export.h>
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#include <linux/uts.h>
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#include <linux/utsname.h>
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@@ -49,3 +50,5 @@ const char linux_proc_banner[] =
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"%s version %s"
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" (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ")"
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" (" LINUX_COMPILER ") %s\n";
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+
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+BUILD_SALT;
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diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
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index 1663fb19343a..dc6d714e4dcb 100644
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--- a/scripts/mod/modpost.c
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+++ b/scripts/mod/modpost.c
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@@ -2125,10 +2125,13 @@ static int check_modname_len(struct module *mod)
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**/
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static void add_header(struct buffer *b, struct module *mod)
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{
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+ buf_printf(b, "#include <linux/build-salt.h>\n");
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buf_printf(b, "#include <linux/module.h>\n");
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buf_printf(b, "#include <linux/vermagic.h>\n");
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buf_printf(b, "#include <linux/compiler.h>\n");
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buf_printf(b, "\n");
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+ buf_printf(b, "BUILD_SALT;\n");
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+ buf_printf(b, "\n");
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buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n");
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buf_printf(b, "MODULE_INFO(name, KBUILD_MODNAME);\n");
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buf_printf(b, "\n");
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--
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2.17.1
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