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Subject[PATCH] scripts/kallsyms: skip ppc compiler stub *.long_branch.* / *.plt_branch.*
Date
PowerPC allmodconfig often fails to build as follows:

LD .tmp_vmlinux.kallsyms1
KSYM .tmp_vmlinux.kallsyms1.o
LD .tmp_vmlinux.kallsyms2
KSYM .tmp_vmlinux.kallsyms2.o
LD .tmp_vmlinux.kallsyms3
KSYM .tmp_vmlinux.kallsyms3.o
LD vmlinux
SORTTAB vmlinux
SYSMAP System.map
Inconsistent kallsyms data
Try make KALLSYMS_EXTRA_PASS=1 as a workaround
make[2]: *** [../Makefile:1162: vmlinux] Error 1

Setting KALLSYMS_EXTRA_PASS=1 does not help.

This is caused by the compiler inserting stubs such as *.long_branch.*
and *.plt_branch.*

$ powerpc-linux-nm -n .tmp_vmlinux.kallsyms2
[ snip ]
c00000000210c000 T __init_begin
c00000000210c000 T _sinittext
c00000000210c010 t 00000075.plt_branch.da9:19
c00000000210c020 t 00000075.plt_branch.1677:5
c00000000210c030 t 00000075.long_branch.memmove
c00000000210c034 t 00000075.plt_branch.9e0:5
c00000000210c044 t 00000075.plt_branch.free_initrd_mem
...

Actually, the problem mentioned in scripts/link-vmlinux.sh comments;
"In theory it's possible this results in even more stubs, but unlikely"
is happening here, and ends up with another kallsyms step required.

scripts/kallsyms.c already ignores various compiler stubs. Let's do
similar to make kallsysms for PowerPC always succeed in 2 steps.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

scripts/kallsyms.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 0096cd965332..306b9b38150f 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -120,17 +120,25 @@ static bool is_ignored_symbol(const char *name, char type)
NULL
};

+ static const char * const ignored_matches[] = {
+ ".long_branch.", /* ppc stub */
+ ".plt_branch.", /* ppc stub */
+ NULL
+ };
+
const char * const *p;

- /* Exclude symbols which vary between passes. */
+ /* ignore symbol names that exactly match to a particular string. */
for (p = ignored_symbols; *p; p++)
if (!strcmp(name, *p))
return true;

+ /* ignore symbol names that start with a particular string. */
for (p = ignored_prefixes; *p; p++)
if (!strncmp(name, *p, strlen(*p)))
return true;

+ /* ignore symbol names that end with a particular string. */
for (p = ignored_suffixes; *p; p++) {
int l = strlen(name) - strlen(*p);

@@ -138,6 +146,12 @@ static bool is_ignored_symbol(const char *name, char type)
return true;
}

+ /* ignore symbol names that contain a particular string. */
+ for (p = ignored_matches; *p; p++) {
+ if (strstr(name, *p))
+ return true;
+ }
+
if (type == 'U' || type == 'u')
return true;
/* exclude debugging symbols */
--
2.25.1
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