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| author | Masahiro Yamada <masahiroy@kernel.org> | 2024-05-20 21:42:09 +0900 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2024-05-29 16:40:03 +0900 |
| commit | 04b8cb0945b4bf679c71dc2351e0d3c25481e3c6 (patch) | |
| tree | 67b4240922e264d508ea96c843c68305a3a58174 /scripts/mksysmap | |
| parent | 659bbf7e1b08267b8e1dd900b316edcb6f6d9e2e (diff) | |
kbuild: avoid unneeded kallsyms step 3
Since commit 951bcae6c5a0 ("kallsyms: Avoid weak references for kallsyms
symbols"), the kallsyms step 3 always occurs.
You can compare the build logs.
[Before 951bcae6c5a0]
$ git checkout 951bcae6c5a0^
$ make defconfig all
[ snip ]
LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.S
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.S
LD vmlinux
[After 951bcae6c5a0]
$ git checkout 951bcae6c5a0
$ make defconfig all
[ snip ]
LD .tmp_vmlinux.kallsyms1
NM .tmp_vmlinux.kallsyms1.syms
KSYMS .tmp_vmlinux.kallsyms1.S
AS .tmp_vmlinux.kallsyms1.S
LD .tmp_vmlinux.kallsyms2
NM .tmp_vmlinux.kallsyms2.syms
KSYMS .tmp_vmlinux.kallsyms2.S
AS .tmp_vmlinux.kallsyms2.S
LD .tmp_vmlinux.kallsyms3 # should not happen
NM .tmp_vmlinux.kallsyms3.syms # should not happen
KSYMS .tmp_vmlinux.kallsyms3.S # should not happen
AS .tmp_vmlinux.kallsyms3.S # should not happen
LD vmlinux
The resulting vmlinux is correct, but it always requires an additional
linking step.
The symbols produced by kallsyms are excluded from kallsyms itself
because they were previously missing in step 1. With those symbols
excluded, the symbol lists matched between step 1 and step 2,
eliminating the need for step 3. Now, this has a negative effect.
Since 951bcae6c5a0, the PROVIDE() directives provide the fallback
definitions, which are not trimmed from the sysbol list in step 1
because ${kallsymso_prev} is empty at this point.
In step 2, ${kallsymso_prev} is set, and the kallsyms_* symbols are
trimmed from the symbol list.
Due to the table size difference between step 1 and step 2 (the former
is larger due to the presence of kallsyms_*), step 3 is triggered.
Now that the kallsyms_* symbols are always linked, let's stop omitting
them from kallsyms. This avoids unnecessary step 3.
Fixes: 951bcae6c5a0 ("kallsyms: Avoid weak references for kallsyms symbols")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'scripts/mksysmap')
| -rwxr-xr-x | scripts/mksysmap | 11 |
1 files changed, 1 insertions, 10 deletions
diff --git a/scripts/mksysmap b/scripts/mksysmap index 57ff5656d566..e46bafe333bd 100755 --- a/scripts/mksysmap +++ b/scripts/mksysmap @@ -4,7 +4,7 @@ # tools to retrieve the actual addresses of symbols in the kernel. # # Usage -# mksysmap vmlinux System.map [exclude] +# mksysmap vmlinux System.map ##### @@ -92,13 +92,4 @@ ${NM} -n ${1} | sed >${2} -e " # ppc stub /\.long_branch\./d /\.plt_branch\./d - -# --------------------------------------------------------------------------- -# Ignored kallsyms symbols -# -# If the 3rd parameter exists, symbols from it will be omitted from the output. -# This makes kallsyms have the identical symbol lists in the step 1 and 2. -# Without this, the step2 would get new symbols generated by scripts/kallsyms.c -# when CONFIG_KALLSYMS_ALL is enabled. That might require one more pass. -$(if [ $# -ge 3 ]; then ${NM} ${3} | sed -n '/ U /!s:.* \([^ ]*\)$:/ \1$/d:p'; fi) " |