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author | Rafael Ávila de Espíndola <rafael@espindo.la> | 2018-12-19 22:01:43 +0300 |
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committer | Borislav Petkov <bp@suse.de> | 2019-01-09 13:22:35 +0300 |
commit | d071ae09a4a1414c1433d5ae9908959a7325b0ad (patch) | |
tree | cdbc37cd26397e57a30c615f75a2c3bea0c74064 /arch/x86/realmode | |
parent | bfeffd155283772bbe78c6a05dec7c0128ee500c (diff) | |
download | linux-d071ae09a4a1414c1433d5ae9908959a7325b0ad.tar.xz |
x86/build: Mark per-CPU symbols as absolute explicitly for LLD
Accessing per-CPU variables is done by finding the offset of the
variable in the per-CPU block and adding it to the address of the
respective CPU's block.
Section 3.10.8 of ld.bfd's documentation states:
For expressions involving numbers, relative addresses and absolute
addresses, ld follows these rules to evaluate terms:
Other binary operations, that is, between two relative addresses
not in the same section, or between a relative address and an
absolute address, first convert any non-absolute term to an
absolute address before applying the operator."
Note that LLVM's linker does not adhere to the GNU ld's implementation
and as such requires implicitly-absolute terms to be explicitly marked
as absolute in the linker script. If not, it fails currently with:
ld.lld: error: ./arch/x86/kernel/vmlinux.lds:153: at least one side of the expression must be absolute
ld.lld: error: ./arch/x86/kernel/vmlinux.lds:154: at least one side of the expression must be absolute
Makefile:1040: recipe for target 'vmlinux' failed
This is not a functional change for ld.bfd which converts the term to an
absolute symbol anyways as specified above.
Based on a previous submission by Tri Vo <trong@android.com>.
Reported-by: Dmitry Golovin <dima@golovin.in>
Signed-off-by: Rafael Ávila de Espíndola <rafael@espindo.la>
[ Update commit message per Boris' and Michael's suggestions. ]
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
[ Massage commit message more, fix typos. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Dmitry Golovin <dima@golovin.in>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Cao Jin <caoj.fnst@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tri Vo <trong@android.com>
Cc: dima@golovin.in
Cc: morbo@google.com
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20181219190145.252035-1-ndesaulniers@google.com
Diffstat (limited to 'arch/x86/realmode')
0 files changed, 0 insertions, 0 deletions