From: Masahiro Yamada <masahiroy@kernel.org> To: Nick Desaulniers <ndesaulniers@google.com> Cc: Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Nathan Chancellor <nathan@kernel.org>, Nicolas Schier <nicolas@fjasle.eu>, Peter Zijlstra <peterz@infradead.org>, linux-modules <linux-modules@vger.kernel.org>, linux-s390 <linux-s390@vger.kernel.org>, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, Ard Biesheuvel <ardb@kernel.org>, Sami Tolvanen <samitolvanen@google.com>, clang-built-linux <llvm@lists.linux.dev> Subject: Re: [PATCH v4 06/14] kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS Date: Tue, 10 May 2022 22:03:31 +0900 [thread overview] Message-ID: <CAK7LNASb40kWgvOM42WyS82p42HQ7Mqhwo3GDffg4yHcKgJk0w@mail.gmail.com> (raw) In-Reply-To: <CAKwvOdm_oSLHddWWSzF5UuYrLCsAwF8AwbUGotUnPvV+6JkSkg@mail.gmail.com> On Tue, May 10, 2022 at 2:51 AM Nick Desaulniers <ndesaulniers@google.com> wrote: > > On Sun, May 8, 2022 at 12:10 PM Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h > > index 07a36a874dca..51ce72ce80fa 100644 > > --- a/include/asm-generic/export.h > > +++ b/include/asm-generic/export.h > > @@ -2,6 +2,14 @@ > > #ifndef __ASM_GENERIC_EXPORT_H > > #define __ASM_GENERIC_EXPORT_H > > > > +/* > > + * This comment block is used by fixdep. Please do not remove. > > I don't know much about fixdep. How does that work, if you could summarize? You can find detailed explanation in scripts/basic/fixdep.c In short, it works like this: fixdep parses every source (including headers). If it finds "CONFIG_MODVERSIONS", it adds a dependency on $(wildcard include/config/MODVERSIONS) to the .cmd files. If CONFIG_MODVERSIONS is toggled in Kconfig, it touches include/config/MODVERSIONS. [1] In the next run of Make, all the sources depending on CONFIG_MODVERSIONS will be re-compiled because the timestamp of include/config/MODVERSIONS is up-to-date. [1]: https://github.com/torvalds/linux/blob/v5.17/scripts/kconfig/confdata.c#L141 > > + * > > + * When CONFIG_MODVERSIONS is changed from n to y, all source files having > > + * EXPORT_SYMBOL variants must be re-compiled because genksyms is run as a > > + * side effect of the .o build rule. > > + */ > > + > > #ifndef KSYM_FUNC > > #define KSYM_FUNC(x) x > > #endif > > @@ -12,9 +20,6 @@ > > #else > > #define KSYM_ALIGN 4 > > #endif > > -#ifndef KCRC_ALIGN > > -#define KCRC_ALIGN 4 > > -#endif > > The #ifndef is there because arch/m68k/include/asm/export.h:1 defines > KCRC_ALIGN. You should delete that, too. Nice catch! I will clean it up too. > > > diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c > > index 4827c5abe5b7..6e6933ae7911 100644 > > --- a/scripts/genksyms/genksyms.c > > +++ b/scripts/genksyms/genksyms.c > > @@ -33,7 +33,7 @@ char *cur_filename; > > int in_source_file; > > > > static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types, > > - flag_preserve, flag_warnings, flag_rel_crcs; > > + flag_preserve, flag_warnings; > > > > static int errors; > > static int nsyms; > > @@ -681,10 +681,7 @@ void export_symbol(const char *name) > > fputs(">\n", debugfile); > > > > /* Used as a linker script. */ > > ^ Does this comment still apply? No. From this commit going forward, the genksyms output will not be used as a linker script. 08/14 will delete this comment anyway, but it is possible to remove it in this commit. > > > - printf(!flag_rel_crcs ? "__crc_%s = 0x%08lx;\n" : > > - "SECTIONS { .rodata : ALIGN(4) { " > > - "__crc_%s = .; LONG(0x%08lx); } }\n", > > - name, crc); > > + printf("__crc_%s = 0x%08lx;\n", name, crc); > > } > > } > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > index eceb3ee7ec06..6aee2401f3ad 100755 > > --- a/scripts/link-vmlinux.sh > > +++ b/scripts/link-vmlinux.sh > > @@ -88,11 +88,6 @@ modpost_link() > > gen_initcalls > > lds="-T .tmp_initcalls.lds" > > > > - if is_enabled CONFIG_MODVERSIONS; then > > - gen_symversions > > ^ this is the only caller of gen_symversions, right? Then > gen_symversions can be cleaned up, too? We can keep it in this commit. The follow-up cleaning is done in 07/14. To avoid too big commit, I separated the build flow change and trivial cleanups. > > > - lds="${lds} -T .tmp_symversions.lds" > > - fi > > - > > # This might take a while, so indicate that we're doing > > # an LTO link > > info LTO ${1} > > @@ -183,6 +178,10 @@ vmlinux_link() > > libs="${KBUILD_VMLINUX_LIBS}" > > fi > > > > + if is_enabled CONFIG_MODULES; then > > + objs="${objs} .vmlinux.export.o" > > + fi > > + > > if [ "${SRCARCH}" = "um" ]; then > > wl=-Wl, > > ld="${CC}" > > @@ -312,6 +311,7 @@ cleanup() > > rm -f vmlinux.o > > rm -f .vmlinux.d > > rm -f .vmlinux.objs > > + rm -f .vmlinux.export.c > > Probably can drop the `rm -f .tmp_symversions.lds` here, too? It will be cleaned up by 07/14. > -- > Thanks, > ~Nick Desaulniers -- Best Regards Masahiro Yamada
WARNING: multiple messages have this Message-ID (diff)
From: Masahiro Yamada <masahiroy@kernel.org> To: Nick Desaulniers <ndesaulniers@google.com> Cc: linux-s390 <linux-s390@vger.kernel.org>, Nicolas Schier <nicolas@fjasle.eu>, Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, clang-built-linux <llvm@lists.linux.dev>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Nathan Chancellor <nathan@kernel.org>, Sami Tolvanen <samitolvanen@google.com>, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, Ard Biesheuvel <ardb@kernel.org>, linux-modules <linux-modules@vger.kernel.org> Subject: Re: [PATCH v4 06/14] kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS Date: Tue, 10 May 2022 22:03:31 +0900 [thread overview] Message-ID: <CAK7LNASb40kWgvOM42WyS82p42HQ7Mqhwo3GDffg4yHcKgJk0w@mail.gmail.com> (raw) In-Reply-To: <CAKwvOdm_oSLHddWWSzF5UuYrLCsAwF8AwbUGotUnPvV+6JkSkg@mail.gmail.com> On Tue, May 10, 2022 at 2:51 AM Nick Desaulniers <ndesaulniers@google.com> wrote: > > On Sun, May 8, 2022 at 12:10 PM Masahiro Yamada <masahiroy@kernel.org> wrote: > > > > diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h > > index 07a36a874dca..51ce72ce80fa 100644 > > --- a/include/asm-generic/export.h > > +++ b/include/asm-generic/export.h > > @@ -2,6 +2,14 @@ > > #ifndef __ASM_GENERIC_EXPORT_H > > #define __ASM_GENERIC_EXPORT_H > > > > +/* > > + * This comment block is used by fixdep. Please do not remove. > > I don't know much about fixdep. How does that work, if you could summarize? You can find detailed explanation in scripts/basic/fixdep.c In short, it works like this: fixdep parses every source (including headers). If it finds "CONFIG_MODVERSIONS", it adds a dependency on $(wildcard include/config/MODVERSIONS) to the .cmd files. If CONFIG_MODVERSIONS is toggled in Kconfig, it touches include/config/MODVERSIONS. [1] In the next run of Make, all the sources depending on CONFIG_MODVERSIONS will be re-compiled because the timestamp of include/config/MODVERSIONS is up-to-date. [1]: https://github.com/torvalds/linux/blob/v5.17/scripts/kconfig/confdata.c#L141 > > + * > > + * When CONFIG_MODVERSIONS is changed from n to y, all source files having > > + * EXPORT_SYMBOL variants must be re-compiled because genksyms is run as a > > + * side effect of the .o build rule. > > + */ > > + > > #ifndef KSYM_FUNC > > #define KSYM_FUNC(x) x > > #endif > > @@ -12,9 +20,6 @@ > > #else > > #define KSYM_ALIGN 4 > > #endif > > -#ifndef KCRC_ALIGN > > -#define KCRC_ALIGN 4 > > -#endif > > The #ifndef is there because arch/m68k/include/asm/export.h:1 defines > KCRC_ALIGN. You should delete that, too. Nice catch! I will clean it up too. > > > diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c > > index 4827c5abe5b7..6e6933ae7911 100644 > > --- a/scripts/genksyms/genksyms.c > > +++ b/scripts/genksyms/genksyms.c > > @@ -33,7 +33,7 @@ char *cur_filename; > > int in_source_file; > > > > static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types, > > - flag_preserve, flag_warnings, flag_rel_crcs; > > + flag_preserve, flag_warnings; > > > > static int errors; > > static int nsyms; > > @@ -681,10 +681,7 @@ void export_symbol(const char *name) > > fputs(">\n", debugfile); > > > > /* Used as a linker script. */ > > ^ Does this comment still apply? No. From this commit going forward, the genksyms output will not be used as a linker script. 08/14 will delete this comment anyway, but it is possible to remove it in this commit. > > > - printf(!flag_rel_crcs ? "__crc_%s = 0x%08lx;\n" : > > - "SECTIONS { .rodata : ALIGN(4) { " > > - "__crc_%s = .; LONG(0x%08lx); } }\n", > > - name, crc); > > + printf("__crc_%s = 0x%08lx;\n", name, crc); > > } > > } > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > index eceb3ee7ec06..6aee2401f3ad 100755 > > --- a/scripts/link-vmlinux.sh > > +++ b/scripts/link-vmlinux.sh > > @@ -88,11 +88,6 @@ modpost_link() > > gen_initcalls > > lds="-T .tmp_initcalls.lds" > > > > - if is_enabled CONFIG_MODVERSIONS; then > > - gen_symversions > > ^ this is the only caller of gen_symversions, right? Then > gen_symversions can be cleaned up, too? We can keep it in this commit. The follow-up cleaning is done in 07/14. To avoid too big commit, I separated the build flow change and trivial cleanups. > > > - lds="${lds} -T .tmp_symversions.lds" > > - fi > > - > > # This might take a while, so indicate that we're doing > > # an LTO link > > info LTO ${1} > > @@ -183,6 +178,10 @@ vmlinux_link() > > libs="${KBUILD_VMLINUX_LIBS}" > > fi > > > > + if is_enabled CONFIG_MODULES; then > > + objs="${objs} .vmlinux.export.o" > > + fi > > + > > if [ "${SRCARCH}" = "um" ]; then > > wl=-Wl, > > ld="${CC}" > > @@ -312,6 +311,7 @@ cleanup() > > rm -f vmlinux.o > > rm -f .vmlinux.d > > rm -f .vmlinux.objs > > + rm -f .vmlinux.export.c > > Probably can drop the `rm -f .tmp_symversions.lds` here, too? It will be cleaned up by 07/14. > -- > Thanks, > ~Nick Desaulniers -- Best Regards Masahiro Yamada
next prev parent reply other threads:[~2022-05-10 13:19 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-08 19:06 [PATCH v4 00/14] kbuild: yet another series of cleanups (modpost, LTO, MODULE_REL_CRCS, export.h) Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 01/14] modpost: remove left-over cross_compile declaration Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-09 17:08 ` Nick Desaulniers 2022-05-09 17:08 ` Nick Desaulniers 2022-05-12 4:35 ` Masahiro Yamada 2022-05-12 4:35 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 02/14] modpost: change the license of EXPORT_SYMBOL to bool type Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-12 4:36 ` Masahiro Yamada 2022-05-12 4:36 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 03/14] modpost: split the section mismatch checks into section-check.c Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-09 17:19 ` Nick Desaulniers 2022-05-09 17:19 ` Nick Desaulniers 2022-05-10 6:55 ` Masahiro Yamada 2022-05-10 6:55 ` Masahiro Yamada 2022-05-11 18:47 ` Nick Desaulniers 2022-05-11 18:47 ` Nick Desaulniers 2022-05-11 19:27 ` Masahiro Yamada 2022-05-11 19:27 ` Masahiro Yamada 2022-05-11 19:51 ` Jeff Johnson 2022-05-11 19:51 ` Jeff Johnson 2022-05-11 20:01 ` Nick Desaulniers 2022-05-11 20:01 ` Nick Desaulniers 2022-05-08 19:06 ` [PATCH v4 04/14] modpost: add sym_find_with_module() helper Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 05/14] modpost: extract symbol versions from *.cmd files Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-09 21:52 ` Sami Tolvanen 2022-05-09 21:52 ` Sami Tolvanen 2022-05-08 19:06 ` [PATCH v4 06/14] kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-09 17:50 ` Nick Desaulniers 2022-05-09 17:50 ` Nick Desaulniers 2022-05-10 13:03 ` Masahiro Yamada [this message] 2022-05-10 13:03 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 07/14] kbuild: stop merging *.symversions Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 08/14] genksyms: adjust the output format to modpost Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 09/14] kbuild: do not create *.prelink.o for Clang LTO or IBT Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-09 23:13 ` Sami Tolvanen 2022-05-09 23:13 ` Sami Tolvanen 2022-05-08 19:06 ` [PATCH v4 10/14] kbuild: check static EXPORT_SYMBOL* by script instead of modpost Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-09 18:05 ` Nick Desaulniers 2022-05-09 18:05 ` Nick Desaulniers 2022-05-10 13:53 ` Masahiro Yamada 2022-05-10 13:53 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 11/14] kbuild: make built-in.a rule robust against too long argument error Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 12/14] kbuild: make *.mod " Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 13/14] kbuild: add cmd_and_savecmd macro Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-08 19:06 ` [PATCH v4 14/14] kbuild: rebuild multi-object modules when objtool is updated Masahiro Yamada 2022-05-08 19:06 ` Masahiro Yamada 2022-05-09 4:24 ` [PATCH v4 00/14] kbuild: yet another series of cleanups (modpost, LTO, MODULE_REL_CRCS, export.h) Masahiro Yamada 2022-05-09 4:24 ` Masahiro Yamada 2022-05-09 22:13 ` Nathan Chancellor 2022-05-09 22:13 ` Nathan Chancellor 2022-05-10 6:55 ` Masahiro Yamada 2022-05-10 6:55 ` Masahiro Yamada 2022-05-09 22:19 ` Nathan Chancellor 2022-05-09 22:19 ` Nathan Chancellor
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