kbuild: add symbol prefix arg to kallsyms

Commit 1f2bfbd00e466ff3489b2ca5cc75b1cccd14c123 ("kbuild: link of
vmlinux moved to a script") introduced in v3.5-rc1 broke kallsyms on
architectures which have symbol prefixes.

The --symbol-prefix argument used to be added to the KALLSYMS command
line from the architecture Makefile, however this isn't picked up by the
new scripts/link-vmlinux.sh. This resulted in symbols like
kallsyms_addresses being added which weren't correctly overriding the
weak symbols such as _kallsyms_addresses. These could then trigger
BUG_ONs in kallsyms code.

This is fixed by removing the KALLSYMS addition from the architecture
Makefile, and using CONFIG_SYMBOL_PREFIX in the link-vmlinux.sh script
to determine whether to add the --symbol-prefix argument.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Bob Liu <lliubbo@gmail.com>

2 files changed, 6 insertions, 2 deletions

diff --git a/arch/blackfin/Makefile b/arch/blackfin/Makefile
index d3d7e64ca96..66cf00095b8 100644
--- a/arch/blackfin/Makefile
+++ b/arch/blackfin/Makefile
@@ -20,7 +20,6 @@ endif
 KBUILD_AFLAGS           += $(call cc-option,-mno-fdpic)
 KBUILD_CFLAGS_MODULE    += -mlong-calls
 LDFLAGS                 += -m elf32bfin
-KALLSYMS         += --symbol-prefix=_
 
 KBUILD_DEFCONFIG := BF537-STAMP_defconfig
 
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 4629038c9e5..df48dda8a2d 100644
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -74,8 +74,13 @@ kallsyms()
         info KSYM ${2}
         local kallsymopt;
 
+        if [ -n "${CONFIG_SYMBOL_PREFIX}" ]; then
+                kallsymopt="${kallsymopt} \
+                            --symbol-prefix=${CONFIG_SYMBOL_PREFIX}"
+        fi
+
         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
-                kallsymopt=--all-symbols
+                kallsymopt="${kallsymopt} --all-symbols"
         fi
 
         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \