[PATCH AUTOSEL 5.8 29/29] scripts/kallsyms: skip ppc compiler stub *.long_branch.* / *.plt_branch.*

Sasha Levin
2020-09-29T01:31:13Z

From: Masahiro Yamada <masahiroy@kernel.org>

[ Upstream commit 516d980f85415d76ae3d0d2a871eb20243f46c95 ]

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 ]
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>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
scripts/kallsyms.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 6dc3078649fa0..e8b26050f5458 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -82,6 +82,7 @@ static char *sym_name(const struct sym_entry *s)

static bool is_ignored_symbol(const char *name, char type)
{
+ /* Symbol names that exactly match to the following are ignored.*/
static const char * const ignored_symbols[] = {
/*
* Symbols which vary between passes. Passes 1 and 2 must have
@@ -104,6 +105,7 @@ static bool is_ignored_symbol(const char *name, char type)
NULL
};

+ /* Symbol names that begin with the following are ignored.*/
static const char * const ignored_prefixes[] = {
"$", /* local symbols for ARM, MIPS, etc. */
".LASANPC", /* s390 kasan local symbols */
@@ -112,6 +114,7 @@ static bool is_ignored_symbol(const char *name, char type)
NULL
};

+ /* Symbol names that end with the following are ignored.*/
static const char * const ignored_suffixes[] = {
"_from_arm", /* arm */
"_from_thumb", /* arm */
@@ -119,9 +122,15 @@ static bool is_ignored_symbol(const char *name, char type)
NULL
};

+ /* Symbol names that contain the following are ignored.*/
+ 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. */
for (p = ignored_symbols; *p; p++)
if (!strcmp(name, *p))
return true;
@@ -137,6 +146,11 @@ static bool is_ignored_symbol(const char *name, char type)
return true;
}

+ 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