From 46b7c49254f89d54f11c58fa629f66e224a16034 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?SZ=20Lin=20=28=E6=9E=97=E4=B8=8A=E6=99=BA=29?= Date: Sun, 1 Mar 2020 00:09:58 +0800 Subject: [PATCH 1/9] kbuild: Fix inconsistent comment MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The commit 2042b5486bd3 ("kbuild: unset variables in top Makefile instead of setting 0") renamed the variable from "config-targets" to "config-build", the comment should be consistent accordingly. Signed-off-by: Kaiden PK Yu (余泊鎧) Signed-off-by: SZ Lin (林上智) Signed-off-by: Masahiro Yamada --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 86035d866f2c..c9199ca3a8b0 100644 --- a/Makefile +++ b/Makefile @@ -1804,7 +1804,7 @@ existing-targets := $(wildcard $(sort $(targets))) -include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd) -endif # config-targets +endif # config-build endif # mixed-build endif # need-sub-make From 8cc4fd73501d9f1370c3eebb70cfe8cc9e24062b Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 10 Mar 2020 19:12:49 +0900 Subject: [PATCH 2/9] kconfig: introduce m32-flag and m64-flag When a compiler supports multiple architectures, some compiler features can be dependent on the target architecture. This is typical for Clang, which supports multiple LLVM backends. Even for GCC, we need to take care of biarch compiler cases. It is not a problem when we evaluate cc-option in Makefiles because cc-option is tested against the flag in question + $(KBUILD_CFLAGS). The cc-option in Kconfig, on the other hand, does not accumulate tested flags. Due to this simplification, it could potentially test cc-option against a different target. At first, Kconfig always evaluated cc-option against the host architecture. Since commit e8de12fb7cde ("kbuild: Check for unknown options with cc-option usage in Kconfig and clang"), in case of cross-compiling with Clang, the target triple is correctly passed to Kconfig. The case with biarch GCC (and native build with Clang) is still not handled properly. We need to pass some flags to specify the target machine bit. Due to the design, all the macros in Kconfig are expanded in the parse stage, where we do not know the target bit size yet. For example, arch/x86/Kconfig allows a user to toggle CONFIG_64BIT. If a compiler flag -foo depends on the machine bit, it must be tested twice, one with -m32 and the other with -m64. However, -m32/-m64 are not always recognized. So, this commits adds m64-flag and m32-flag macros. They expand to -m32, -m64, respectively if supported. Or, they expand to an empty string if unsupported. The typical usage is like this: config FOO bool default $(cc-option,$(m64-flag) -foo) if 64BIT default $(cc-option,$(m32-flag) -foo) This is clumsy, but there is no elegant way to handle this in the current static macro expansion. There was discussion for static functions vs dynamic functions. The consensus was to go as far as possible with the static functions. (https://lkml.org/lkml/2018/3/2/22) Signed-off-by: Masahiro Yamada Tested-by: George Spelvin Reviewed-by: Nathan Chancellor --- scripts/Kconfig.include | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include index 85334dc8c997..496d11c92c97 100644 --- a/scripts/Kconfig.include +++ b/scripts/Kconfig.include @@ -44,3 +44,10 @@ $(error-if,$(success, $(LD) -v | grep -q gold), gold linker '$(LD)' not supporte # gcc version including patch level gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh $(CC)) + +# machine bit flags +# $(m32-flag): -m32 if the compiler supports it, or an empty string otherwise. +# $(m64-flag): -m64 if the compiler supports it, or an empty string otherwise. +cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$(1)) +m32-flag := $(cc-option-bit,-m32) +m64-flag := $(cc-option-bit,-m64) From 3a7c733165a4799fa1beb262fe244bfbcdd1c163 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 10 Mar 2020 19:12:50 +0900 Subject: [PATCH 3/9] int128: fix __uint128_t compiler test in Kconfig The support for __uint128_t is dependent on the target bit size. GCC that defaults to the 32-bit can still build the 64-bit kernel with -m64 flag passed. However, $(cc-option,-D__SIZEOF_INT128__=0) is evaluated against the default machine bit, which may not match to the kernel it is building. Theoretically, this could be evaluated separately for 64BIT/32BIT. config CC_HAS_INT128 bool default !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) if 64BIT default !$(cc-option,$(m32-flag) -D__SIZEOF_INT128__=0) I simplified it more because the 32-bit compiler is unlikely to support __uint128_t. Fixes: c12d3362a74b ("int128: move __uint128_t compiler test to Kconfig") Reported-by: George Spelvin Signed-off-by: Masahiro Yamada Tested-by: George Spelvin --- init/Kconfig | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index 20a6ac33761c..4f717bfdbfe2 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -767,8 +767,7 @@ config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH bool config CC_HAS_INT128 - def_bool y - depends on !$(cc-option,-D__SIZEOF_INT128__=0) + def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT # # For architectures that know their GCC __int128 support is sound From 2eebb7abefb9f95b412c51add3d8216980bf6066 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 12 Mar 2020 07:50:44 +0900 Subject: [PATCH 4/9] kbuild: doc: fix references to other documents All the files in Documentation/kbuild/ were converted to reST. Signed-off-by: Masahiro Yamada --- Documentation/kbuild/kbuild.rst | 2 +- Documentation/kbuild/kconfig-macro-language.rst | 2 +- Documentation/kbuild/makefiles.rst | 6 +++--- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst index f1e5dce86af7..510f38d7e78a 100644 --- a/Documentation/kbuild/kbuild.rst +++ b/Documentation/kbuild/kbuild.rst @@ -237,7 +237,7 @@ This is solely useful to speed up test compiles. KBUILD_EXTRA_SYMBOLS -------------------- For modules that use symbols from other modules. -See more details in modules.txt. +See more details in modules.rst. ALLSOURCE_ARCHS --------------- diff --git a/Documentation/kbuild/kconfig-macro-language.rst b/Documentation/kbuild/kconfig-macro-language.rst index 35b3263b7e40..8b413ef9603d 100644 --- a/Documentation/kbuild/kconfig-macro-language.rst +++ b/Documentation/kbuild/kconfig-macro-language.rst @@ -44,7 +44,7 @@ intermediate:: def_bool y Then, Kconfig moves onto the evaluation stage to resolve inter-symbol -dependency as explained in kconfig-language.txt. +dependency as explained in kconfig-language.rst. Variables diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 6bc126a14b3d..04d5c01a2e99 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -924,7 +924,7 @@ When kbuild executes, the following steps are followed (roughly): $(KBUILD_AFLAGS_MODULE) is used to add arch-specific options that are used for assembler. - From commandline AFLAGS_MODULE shall be used (see kbuild.txt). + From commandline AFLAGS_MODULE shall be used (see kbuild.rst). KBUILD_CFLAGS_KERNEL $(CC) options specific for built-in @@ -937,7 +937,7 @@ When kbuild executes, the following steps are followed (roughly): $(KBUILD_CFLAGS_MODULE) is used to add arch-specific options that are used for $(CC). - From commandline CFLAGS_MODULE shall be used (see kbuild.txt). + From commandline CFLAGS_MODULE shall be used (see kbuild.rst). KBUILD_LDFLAGS_MODULE Options for $(LD) when linking modules @@ -945,7 +945,7 @@ When kbuild executes, the following steps are followed (roughly): $(KBUILD_LDFLAGS_MODULE) is used to add arch-specific options used when linking modules. This is often a linker script. - From commandline LDFLAGS_MODULE shall be used (see kbuild.txt). + From commandline LDFLAGS_MODULE shall be used (see kbuild.rst). KBUILD_LDS From 82f2bc2fcc0160d6f82dd1ac64518ae0a4dd183f Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 11 Mar 2020 12:41:21 -0700 Subject: [PATCH 5/9] kbuild: Disable -Wpointer-to-enum-cast Clang's -Wpointer-to-int-cast deviates from GCC in that it warns when casting to enums. The kernel does this in certain places, such as device tree matches to set the version of the device being used, which allows the kernel to avoid using a gigantic union. https://elixir.bootlin.com/linux/v5.5.8/source/drivers/ata/ahci_brcm.c#L428 https://elixir.bootlin.com/linux/v5.5.8/source/drivers/ata/ahci_brcm.c#L402 https://elixir.bootlin.com/linux/v5.5.8/source/include/linux/mod_devicetable.h#L264 To avoid a ton of false positive warnings, disable this particular part of the warning, which has been split off into a separate diagnostic so that the entire warning does not need to be turned off for clang. It will be visible under W=1 in case people want to go about fixing these easily and enabling the warning treewide. Cc: stable@vger.kernel.org Link: https://github.com/ClangBuiltLinux/linux/issues/887 Link: https://github.com/llvm/llvm-project/commit/2a41b31fcdfcb67ab7038fc2ffb606fd50b83a84 Signed-off-by: Nathan Chancellor Signed-off-by: Masahiro Yamada --- scripts/Makefile.extrawarn | 1 + 1 file changed, 1 insertion(+) diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index ecddf83ac142..ca08f2fe7c34 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -48,6 +48,7 @@ KBUILD_CFLAGS += -Wno-initializer-overrides KBUILD_CFLAGS += -Wno-format KBUILD_CFLAGS += -Wno-sign-compare KBUILD_CFLAGS += -Wno-format-zero-length +KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast) endif endif From 5190044c2965514a973184ca68ef5fad57a24670 Mon Sep 17 00:00:00 2001 From: Jessica Yu Date: Wed, 11 Mar 2020 18:01:20 +0100 Subject: [PATCH 6/9] modpost: move the namespace field in Module.symvers last In order to preserve backwards compatability with kmod tools, we have to move the namespace field in Module.symvers last, as the depmod -e -E option looks at the first three fields in Module.symvers to check symbol versions (and it's expected they stay in the original order of crc, symbol, module). In addition, update an ancient comment above read_dump() in modpost that suggested that the export type field in Module.symvers was optional. I suspect that there were historical reasons behind that comment that are no longer accurate. We have been unconditionally printing the export type since 2.6.18 (commit bd5cbcedf44), which is over a decade ago now. Fix up read_dump() to treat each field as non-optional. I suspect the original read_dump() code treated the export field as optional in order to support pre <= 2.6.18 Module.symvers (which did not have the export type field). Note that although symbol namespaces are optional, the field will not be omitted from Module.symvers if a symbol does not have a namespace. In this case, the field will simply be empty and the next delimiter or end of line will follow. Cc: stable@vger.kernel.org Fixes: cb9b55d21fe0 ("modpost: add support for symbol namespaces") Tested-by: Matthias Maennich Reviewed-by: Matthias Maennich Reviewed-by: Lucas De Marchi Signed-off-by: Jessica Yu Signed-off-by: Masahiro Yamada --- Documentation/kbuild/modules.rst | 4 ++-- scripts/export_report.pl | 2 +- scripts/mod/modpost.c | 24 ++++++++++++------------ 3 files changed, 15 insertions(+), 15 deletions(-) diff --git a/Documentation/kbuild/modules.rst b/Documentation/kbuild/modules.rst index 69fa48ee93d6..e0b45a257f21 100644 --- a/Documentation/kbuild/modules.rst +++ b/Documentation/kbuild/modules.rst @@ -470,9 +470,9 @@ build. The syntax of the Module.symvers file is:: - + - 0xe1cc2a05 usb_stor_suspend USB_STORAGE drivers/usb/storage/usb-storage EXPORT_SYMBOL_GPL + 0xe1cc2a05 usb_stor_suspend drivers/usb/storage/usb-storage EXPORT_SYMBOL_GPL USB_STORAGE The fields are separated by tabs and values may be empty (e.g. if no namespace is defined for an exported symbol). diff --git a/scripts/export_report.pl b/scripts/export_report.pl index 548330e8c4e7..feb3d5542a62 100755 --- a/scripts/export_report.pl +++ b/scripts/export_report.pl @@ -94,7 +94,7 @@ if (defined $opt{'o'}) { # while ( <$module_symvers> ) { chomp; - my (undef, $symbol, $namespace, $module, $gpl) = split('\t'); + my (undef, $symbol, $module, $gpl, $namespace) = split('\t'); $SYMBOL { $symbol } = [ $module , "0" , $symbol, $gpl]; } close($module_symvers); diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 7edfdb2f4497..6ab235354f36 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -2427,7 +2427,7 @@ static void write_if_changed(struct buffer *b, const char *fname) } /* parse Module.symvers file. line format: - * 0x12345678symbolmodule[[export]something] + * 0x12345678symbolmoduleexportnamespace **/ static void read_dump(const char *fname, unsigned int kernel) { @@ -2440,7 +2440,7 @@ static void read_dump(const char *fname, unsigned int kernel) return; while ((line = get_next_line(&pos, file, size))) { - char *symname, *namespace, *modname, *d, *export, *end; + char *symname, *namespace, *modname, *d, *export; unsigned int crc; struct module *mod; struct symbol *s; @@ -2448,16 +2448,16 @@ static void read_dump(const char *fname, unsigned int kernel) if (!(symname = strchr(line, '\t'))) goto fail; *symname++ = '\0'; - if (!(namespace = strchr(symname, '\t'))) - goto fail; - *namespace++ = '\0'; - if (!(modname = strchr(namespace, '\t'))) + if (!(modname = strchr(symname, '\t'))) goto fail; *modname++ = '\0'; - if ((export = strchr(modname, '\t')) != NULL) - *export++ = '\0'; - if (export && ((end = strchr(export, '\t')) != NULL)) - *end = '\0'; + if (!(export = strchr(modname, '\t'))) + goto fail; + *export++ = '\0'; + if (!(namespace = strchr(export, '\t'))) + goto fail; + *namespace++ = '\0'; + crc = strtoul(line, &d, 16); if (*symname == '\0' || *modname == '\0' || *d != '\0') goto fail; @@ -2508,9 +2508,9 @@ static void write_dump(const char *fname) namespace = symbol->namespace; buf_printf(&buf, "0x%08x\t%s\t%s\t%s\t%s\n", symbol->crc, symbol->name, - namespace ? namespace : "", symbol->module->name, - export_str(symbol->export)); + export_str(symbol->export), + namespace ? namespace : ""); } symbol = symbol->next; } From 785d74ec3bbf26ac7f6e92e6e96a259aec0f107a Mon Sep 17 00:00:00 2001 From: Eugeniy Paltsev Date: Mon, 16 Mar 2020 14:25:19 +0300 Subject: [PATCH 7/9] initramfs: restore default compression behavior Even though INITRAMFS_SOURCE kconfig option isn't set in most of defconfigs it is used (set) extensively by various build systems. Commit f26661e12765 ("initramfs: make initramfs compression choice non-optional") has changed default compression mode. Previously we compress initramfs using available compression algorithm. Now we don't use any compression at all by default. It significantly increases the image size in case of build system chooses embedded initramfs. Initially I faced with this issue while using buildroot. As of today it's not possible to set preferred compression mode in target defconfig as this option depends on INITRAMFS_SOURCE being set. Modification of all build systems either doesn't look like good option. Let's instead rewrite initramfs compression mode choices list the way that "INITRAMFS_COMPRESSION_NONE" will be the last option in the list. In that case it will be chosen only if all other options (which implements any compression) are not available. Signed-off-by: Eugeniy Paltsev Signed-off-by: Masahiro Yamada --- usr/Kconfig | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/usr/Kconfig b/usr/Kconfig index bdf5bbd40727..96afb03b65f9 100644 --- a/usr/Kconfig +++ b/usr/Kconfig @@ -124,17 +124,6 @@ choice If in doubt, select 'None' -config INITRAMFS_COMPRESSION_NONE - bool "None" - help - Do not compress the built-in initramfs at all. This may sound wasteful - in space, but, you should be aware that the built-in initramfs will be - compressed at a later stage anyways along with the rest of the kernel, - on those architectures that support this. However, not compressing the - initramfs may lead to slightly higher memory consumption during a - short time at boot, while both the cpio image and the unpacked - filesystem image will be present in memory simultaneously - config INITRAMFS_COMPRESSION_GZIP bool "Gzip" depends on RD_GZIP @@ -207,4 +196,15 @@ config INITRAMFS_COMPRESSION_LZ4 If you choose this, keep in mind that most distros don't provide lz4 by default which could cause a build failure. +config INITRAMFS_COMPRESSION_NONE + bool "None" + help + Do not compress the built-in initramfs at all. This may sound wasteful + in space, but, you should be aware that the built-in initramfs will be + compressed at a later stage anyways along with the rest of the kernel, + on those architectures that support this. However, not compressing the + initramfs may lead to slightly higher memory consumption during a + short time at boot, while both the cpio image and the unpacked + filesystem image will be present in memory simultaneously + endchoice From 4b8a5cfb5fd375cf4c7502a18f0096ed2881be27 Mon Sep 17 00:00:00 2001 From: Xiao Yang Date: Wed, 18 Mar 2020 18:34:16 +0800 Subject: [PATCH 8/9] modpost: Get proper section index by get_secindex() instead of st_shndx (uint16_t) st_shndx is limited to 65535(i.e. SHN_XINDEX) so sym_get_data() gets wrong section index by st_shndx if requested symbol contains extended section index that is more than 65535. In this case, we need to get proper section index by .symtab_shndx section. Module.symvers generated by building kernel with "-ffunction-sections -fdata-sections" shows the issue. Fixes: 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting relative CRCs") Fixes: e84f9fbbece1 ("modpost: refactor namespace_from_kstrtabns() to not hard-code section name") Signed-off-by: Xiao Yang Signed-off-by: Masahiro Yamada --- scripts/mod/modpost.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 6ab235354f36..55a0a2eccbd2 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -308,7 +308,8 @@ static const char *sec_name(struct elf_info *elf, int secindex) static void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym) { - Elf_Shdr *sechdr = &info->sechdrs[sym->st_shndx]; + unsigned int secindex = get_secindex(info, sym); + Elf_Shdr *sechdr = &info->sechdrs[secindex]; unsigned long offset; offset = sym->st_value; From 7883a14339299773b2ce08dcfd97c63c199a9289 Mon Sep 17 00:00:00 2001 From: Mikhail Petrov Date: Wed, 11 Mar 2020 23:37:09 +0300 Subject: [PATCH 9/9] scripts/kallsyms: fix wrong kallsyms_relative_base There is the code in the read_symbol function in 'scripts/kallsyms.c': if (is_ignored_symbol(name, type)) return NULL; /* Ignore most absolute/undefined (?) symbols. */ if (strcmp(name, "_text") == 0) _text = addr; But the is_ignored_symbol function returns true for name="_text" and type='A'. So the next condition is not executed and the _text variable is always zero. It makes the wrong kallsyms_relative_base symbol as a result of the code (CONFIG_KALLSYMS_BASE_RELATIVE is defined): if (base_relative) { output_label("kallsyms_relative_base"); output_address(relative_base); printf("\n"); } Because the output_address function uses the _text variable. So the kallsyms_lookup function and all related functions in the kernel do not work properly. For example, the stack trace in oops: Call Trace: [aa095e58] [809feab8] kobj_ns_ops_tbl+0x7ff09ac8/0x7ff1c1c4 (unreliable) [aa095e98] [80002b64] kobj_ns_ops_tbl+0x7f50db74/0x80000010 [aa095ef8] [809c3d24] kobj_ns_ops_tbl+0x7feced34/0x7ff1c1c4 [aa095f28] [80002ed0] kobj_ns_ops_tbl+0x7f50dee0/0x80000010 [aa095f38] [8000f238] kobj_ns_ops_tbl+0x7f51a248/0x80000010 The right stack trace: Call Trace: [aa095e58] [809feab8] module_vdu_video_init+0x2fc/0x3bc (unreliable) [aa095e98] [80002b64] do_one_initcall+0x40/0x1f0 [aa095ef8] [809c3d24] kernel_init_freeable+0x164/0x1d8 [aa095f28] [80002ed0] kernel_init+0x14/0x124 [aa095f38] [8000f238] ret_from_kernel_thread+0x14/0x1c [masahiroy@kernel.org: This issue happens on binutils <= 2.22 The following commit fixed it: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d2667025dd30611514810c28bee9709e4623012a The symbol type of _text is 'T' on binutils >= 2.23 The minimal supported binutils version for the kernel build is 2.21 ] Signed-off-by: Mikhail Petrov Signed-off-by: Masahiro Yamada --- scripts/kallsyms.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 0133dfaaf352..3e8dea6e0a95 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -195,13 +195,13 @@ static struct sym_entry *read_symbol(FILE *in) return NULL; } - if (is_ignored_symbol(name, type)) - return NULL; - - /* Ignore most absolute/undefined (?) symbols. */ if (strcmp(name, "_text") == 0) _text = addr; + /* Ignore most absolute/undefined (?) symbols. */ + if (is_ignored_symbol(name, type)) + return NULL; + check_symbol_range(name, addr, text_ranges, ARRAY_SIZE(text_ranges)); check_symbol_range(name, addr, &percpu_range, 1);