linux-stable/include/linux/build-salt.h

#ifndef __BUILD_SALT_H
#define __BUILD_SALT_H

#include <linux/elfnote.h>

#define LINUX_ELFNOTE_BUILD_SALT       0x100

#ifdef __ASSEMBLER__

#define BUILD_SALT \
       ELFNOTE(Linux, LINUX_ELFNOTE_BUILD_SALT, .asciz CONFIG_BUILD_SALT)

#else

#define BUILD_SALT \
       ELFNOTE32("Linux", LINUX_ELFNOTE_BUILD_SALT, CONFIG_BUILD_SALT)

#endif

#endif /* __BUILD_SALT_H */
kbuild: Add build salt to the kernel and modules In Fedora, the debug information is packaged separately (foo-debuginfo) and can be installed separately. There's been a long standing issue where only one version of a debuginfo info package can be installed at a time. There's been an effort for Fedora for parallel debuginfo to rectify this problem. Part of the requirement to allow parallel debuginfo to work is that build ids are unique between builds. The existing upstream rpm implementation ensures this by re-calculating the build-id using the version and release as a seed. This doesn't work 100% for the kernel because of the vDSO which is its own binary and doesn't get updated when embedded. Fix this by adding some data in an ELF note for both the kernel and modules. The data is controlled via a Kconfig option so distributions can set it to an appropriate value to ensure uniqueness between builds. Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Laura Abbott <labbott@redhat.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> 2018-07-06 00:49:37 +00:00			`#ifndef __BUILD_SALT_H`
			`#define __BUILD_SALT_H`

			`#include <linux/elfnote.h>`

			`#define LINUX_ELFNOTE_BUILD_SALT 0x100`

			`#ifdef __ASSEMBLER__`

			`#define BUILD_SALT \`
			`ELFNOTE(Linux, LINUX_ELFNOTE_BUILD_SALT, .asciz CONFIG_BUILD_SALT)`

			`#else`

			`#define BUILD_SALT \`
			`ELFNOTE32("Linux", LINUX_ELFNOTE_BUILD_SALT, CONFIG_BUILD_SALT)`

			`#endif`

			`#endif /* __BUILD_SALT_H */`