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authorNicholas Piggin <npiggin@gmail.com>2016-11-24 03:41:37 +1100
committerMichal Marek <mmarek@suse.com>2016-11-29 15:53:19 +0100
commit7e2b37c971a2a20ec8a311a195a626c16c774031 (patch)
tree7a6758f281848f72ee464d0a7f92f3aebb849225 /scripts/link-vmlinux.sh
parent1001354ca34179f3db924eb66672442a173147dc (diff)
downloadleg-kernel-7e2b37c971a2a20ec8a311a195a626c16c774031.tar.gz
kbuild: kallsyms allow 3-pass generation if symbols size has changed
kallsyms generation is not foolproof, due to some linkers adding symbols (e.g., branch trampolines) when a binary size changes. Have it attempt a 3rd pass automatically if the kallsyms size changes in the 2nd pass. This allows powerpc64 allyesconfig to build without adding another pass when it's not required. This can be solved other ways by directing the linker not to add labels on branch stubs, or to move kallsyms near the end of the image. The former is undesirable for debugging/tracing, and the latter is a more significant change that requires more testing and review. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
Diffstat (limited to 'scripts/link-vmlinux.sh')
-rwxr-xr-xscripts/link-vmlinux.sh19
1 files changed, 13 insertions, 6 deletions
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index f742c65108b9..6b94fe4e932d 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -246,10 +246,14 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then
# the right size, but due to the added section, some
# addresses have shifted.
# From here, we generate a correct .tmp_kallsyms2.o
- # 2a) We may use an extra pass as this has been necessary to
- # woraround some alignment related bugs.
- # KALLSYMS_EXTRA_PASS=1 is used to trigger this.
- # 3) The correct ${kallsymso} is linked into the final vmlinux.
+ # 3) That link may have expanded the kernel image enough that
+ # more linker branch stubs / trampolines had to be added, which
+ # introduces new names, which further expands kallsyms. Do another
+ # pass if that is the case. In theory it's possible this results
+ # in even more stubs, but unlikely.
+ # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
+ # other bugs.
+ # 4) The correct ${kallsymso} is linked into the final vmlinux.
#
# a) Verify that the System.map from vmlinux matches the map from
# ${kallsymso}.
@@ -265,8 +269,11 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then
vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
- # step 2a
- if [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
+ # step 3
+ size1=$(stat -c "%s" .tmp_kallsyms1.o)
+ size2=$(stat -c "%s" .tmp_kallsyms2.o)
+
+ if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
kallsymso=.tmp_kallsyms3.o
kallsyms_vmlinux=.tmp_vmlinux3