[PATCH v5 1/3] x86: kallsyms: disable absolute percpu symbols on !SMP

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

scripts/kallsyms.c has a special --absolute-percpu command line
option which deals with the zero based per cpu offsets that are
used when building for SMP on x86_64. This means that the option
should only be passed in that case, so add a Kconfig symbol with
the correct predicate, and use that instead.

Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 init/Kconfig            | 4 ++++
 scripts/link-vmlinux.sh | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/init/Kconfig b/init/Kconfig
index 22320804fbaf..b17824a875fa 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1420,6 +1420,10 @@ config KALLSYMS_ALL
 
 	   Say N unless you really need all symbols.
 
+config KALLSYMS_ABSOLUTE_PERCPU
+	bool
+	default X86_64 && SMP
+
 config PRINTK
 	default y
 	bool "Enable support for printk" if EXPERT
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index ba6c34ea5429..7a08bf9a9576 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -86,7 +86,7 @@ kallsyms()
 		kallsymopt="${kallsymopt} --page-offset=$CONFIG_PAGE_OFFSET"
 	fi
 
-	if [ -n "${CONFIG_X86_64}" ]; then
+	if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 		kallsymopt="${kallsymopt} --absolute-percpu"
 	fi
 
-- 
2.5.0