* [PATCH] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols @ 2021-01-14 5:48 Fangrui Song 2021-01-14 14:06 ` Jessica Yu 0 siblings, 1 reply; 13+ messages in thread From: Fangrui Song @ 2021-01-14 5:48 UTC (permalink / raw) To: linux-kernel, Jessica Yu; +Cc: clang-built-linux, Fangrui Song, Marco Elver clang-12 -fno-pic (since https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` on x86. The two forms should have identical behaviors on x86-64 but the former causes GNU as<2.37 to produce an unreferenced undefined symbol _GLOBAL_OFFSET_TABLE_. (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the linker behavior is identical as far as Linux kernel is concerned.) Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for external function calls on x86. Note: ld -z defs and dynamic loaders do not error for unreferenced undefined symbols so the module loader is reading too much. If we ever need to ignore more symbols, the code should be refactored to ignore unreferenced symbols. Reported-by: Marco Elver <melver@google.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1250 Signed-off-by: Fangrui Song <maskray@google.com> --- kernel/module.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 4bf30e4b3eaa..2e2deea99289 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2395,8 +2395,14 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) break; } - /* Ok if weak. */ - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) + /* Ok if weak. Also allow _GLOBAL_OFFSET_TABLE_: + * GNU as before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ + * for call foo@PLT on x86-64. If the code ever needs to ignore + * more symbols, refactor the code to only warn if referenced by + * a relocation. + */ + if (!ksym && (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || + !strcmp(name, "_GLOBAL_OFFSET_TABLE_"))) break; ret = PTR_ERR(ksym) ?: -ENOENT; -- 2.30.0.284.gd98b1dd5eaa7-goog ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-14 5:48 [PATCH] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols Fangrui Song @ 2021-01-14 14:06 ` Jessica Yu 2021-01-14 16:57 ` Fāng-ruì Sòng 0 siblings, 1 reply; 13+ messages in thread From: Jessica Yu @ 2021-01-14 14:06 UTC (permalink / raw) To: Fangrui Song; +Cc: linux-kernel, clang-built-linux, Marco Elver +++ Fangrui Song [13/01/21 21:48 -0800]: >clang-12 -fno-pic (since >https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) >can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` >on x86. The two forms should have identical behaviors on x86-64 but the >former causes GNU as<2.37 to produce an unreferenced undefined symbol >_GLOBAL_OFFSET_TABLE_. > >(On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the >linker behavior is identical as far as Linux kernel is concerned.) > >Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what >scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the >problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for >external function calls on x86. > >Note: ld -z defs and dynamic loaders do not error for unreferenced >undefined symbols so the module loader is reading too much. If we ever >need to ignore more symbols, the code should be refactored to ignore >unreferenced symbols. > >Reported-by: Marco Elver <melver@google.com> >Link: https://github.com/ClangBuiltLinux/linux/issues/1250 >Signed-off-by: Fangrui Song <maskray@google.com> >--- > kernel/module.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > >diff --git a/kernel/module.c b/kernel/module.c >index 4bf30e4b3eaa..2e2deea99289 100644 >--- a/kernel/module.c >+++ b/kernel/module.c >@@ -2395,8 +2395,14 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) > break; > } > >- /* Ok if weak. */ >- if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) >+ /* Ok if weak. Also allow _GLOBAL_OFFSET_TABLE_: >+ * GNU as before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ >+ * for call foo@PLT on x86-64. If the code ever needs to ignore >+ * more symbols, refactor the code to only warn if referenced by >+ * a relocation. >+ */ >+ if (!ksym && (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || >+ !strcmp(name, "_GLOBAL_OFFSET_TABLE_"))) > break; Hi Fangrui, Thanks for the patch. I am puzzled why we don't already mirror modpost here, that particular line of code in modpost to ignore _GLOBAL_OFFSET_TABLE_ has been there long before my time. Let's properly mirror modpost then, and create a similar helper function ignore_undef_symbol() (and stick the _GLOBAL_OFFSET_TABLE_ check in there) to account for future cases like this. Thanks, Jessica ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-14 14:06 ` Jessica Yu @ 2021-01-14 16:57 ` Fāng-ruì Sòng 2021-01-14 21:18 ` Jessica Yu 0 siblings, 1 reply; 13+ messages in thread From: Fāng-ruì Sòng @ 2021-01-14 16:57 UTC (permalink / raw) To: Jessica Yu, Sam Ravnborg; +Cc: LKML, clang-built-linux, Marco Elver On Thu, Jan 14, 2021 at 6:06 AM Jessica Yu <jeyu@kernel.org> wrote: > > +++ Fangrui Song [13/01/21 21:48 -0800]: > >clang-12 -fno-pic (since > >https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) > >can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` > >on x86. The two forms should have identical behaviors on x86-64 but the > >former causes GNU as<2.37 to produce an unreferenced undefined symbol > >_GLOBAL_OFFSET_TABLE_. > > > >(On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the > >linker behavior is identical as far as Linux kernel is concerned.) > > > >Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what > >scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the > >problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for > >external function calls on x86. > > > >Note: ld -z defs and dynamic loaders do not error for unreferenced > >undefined symbols so the module loader is reading too much. If we ever > >need to ignore more symbols, the code should be refactored to ignore > >unreferenced symbols. > > > >Reported-by: Marco Elver <melver@google.com> > >Link: https://github.com/ClangBuiltLinux/linux/issues/1250 > >Signed-off-by: Fangrui Song <maskray@google.com> > >--- > > kernel/module.c | 10 ++++++++-- > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > >diff --git a/kernel/module.c b/kernel/module.c > >index 4bf30e4b3eaa..2e2deea99289 100644 > >--- a/kernel/module.c > >+++ b/kernel/module.c > >@@ -2395,8 +2395,14 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) > > break; > > } > > > >- /* Ok if weak. */ > >- if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) > >+ /* Ok if weak. Also allow _GLOBAL_OFFSET_TABLE_: > >+ * GNU as before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ > >+ * for call foo@PLT on x86-64. If the code ever needs to ignore > >+ * more symbols, refactor the code to only warn if referenced by > >+ * a relocation. > >+ */ > >+ if (!ksym && (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || > >+ !strcmp(name, "_GLOBAL_OFFSET_TABLE_"))) > > break; > > Hi Fangrui, > > Thanks for the patch. I am puzzled why we don't already mirror modpost > here, that particular line of code in modpost to ignore _GLOBAL_OFFSET_TABLE_ > has been there long before my time. Let's properly mirror modpost > then, and create a similar helper function ignore_undef_symbol() (and > stick the _GLOBAL_OFFSET_TABLE_ check in there) to account for future > cases like this. > > Thanks, > > Jessica Hi Jessica, I guess __this_module in scripts/mod/modpost.c:ignore_undef_symbol is not a problem. For PPC64 _restgpr0_* and _savegpr0_*, I am not sure ignoring the undefined functions in kernel/module.c is right. (I know they can be produced by gcc -Os in some cases (https://reviews.llvm.org/D79977), but I want to learn whether that is a real issue before adding them.) If we ever need to ignore more symbols, the code should be refactored to not warn for unreferenced undefined symbols as my description says. ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-14 16:57 ` Fāng-ruì Sòng @ 2021-01-14 21:18 ` Jessica Yu 2021-01-14 21:54 ` [PATCH v2] " Fangrui Song 2021-01-15 19:52 ` [PATCH v3] " Fangrui Song 0 siblings, 2 replies; 13+ messages in thread From: Jessica Yu @ 2021-01-14 21:18 UTC (permalink / raw) To: Fāng-ruì Sòng Cc: Sam Ravnborg, LKML, clang-built-linux, Marco Elver +++ Fāng-ruì Sòng [14/01/21 08:57 -0800]: >On Thu, Jan 14, 2021 at 6:06 AM Jessica Yu <jeyu@kernel.org> wrote: >> >> +++ Fangrui Song [13/01/21 21:48 -0800]: >> >clang-12 -fno-pic (since >> >https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) >> >can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` >> >on x86. The two forms should have identical behaviors on x86-64 but the >> >former causes GNU as<2.37 to produce an unreferenced undefined symbol >> >_GLOBAL_OFFSET_TABLE_. >> > >> >(On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the >> >linker behavior is identical as far as Linux kernel is concerned.) >> > >> >Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what >> >scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the >> >problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for >> >external function calls on x86. >> > >> >Note: ld -z defs and dynamic loaders do not error for unreferenced >> >undefined symbols so the module loader is reading too much. If we ever >> >need to ignore more symbols, the code should be refactored to ignore >> >unreferenced symbols. >> > >> >Reported-by: Marco Elver <melver@google.com> >> >Link: https://github.com/ClangBuiltLinux/linux/issues/1250 >> >Signed-off-by: Fangrui Song <maskray@google.com> >> >--- >> > kernel/module.c | 10 ++++++++-- >> > 1 file changed, 8 insertions(+), 2 deletions(-) >> > >> >diff --git a/kernel/module.c b/kernel/module.c >> >index 4bf30e4b3eaa..2e2deea99289 100644 >> >--- a/kernel/module.c >> >+++ b/kernel/module.c >> >@@ -2395,8 +2395,14 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) >> > break; >> > } >> > >> >- /* Ok if weak. */ >> >- if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) >> >+ /* Ok if weak. Also allow _GLOBAL_OFFSET_TABLE_: >> >+ * GNU as before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ >> >+ * for call foo@PLT on x86-64. If the code ever needs to ignore >> >+ * more symbols, refactor the code to only warn if referenced by >> >+ * a relocation. >> >+ */ >> >+ if (!ksym && (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || >> >+ !strcmp(name, "_GLOBAL_OFFSET_TABLE_"))) >> > break; >> >> Hi Fangrui, >> >> Thanks for the patch. I am puzzled why we don't already mirror modpost >> here, that particular line of code in modpost to ignore _GLOBAL_OFFSET_TABLE_ >> has been there long before my time. Let's properly mirror modpost >> then, and create a similar helper function ignore_undef_symbol() (and >> stick the _GLOBAL_OFFSET_TABLE_ check in there) to account for future >> cases like this. >> >> Thanks, >> >> Jessica > >Hi Jessica, > >I guess __this_module in scripts/mod/modpost.c:ignore_undef_symbol is >not a problem. >For PPC64 _restgpr0_* and _savegpr0_*, I am not sure ignoring the >undefined functions in kernel/module.c is right. >(I know they can be produced by gcc -Os in some cases >(https://reviews.llvm.org/D79977), but I want to learn whether that is >a real issue before adding them.) > >If we ever need to ignore more symbols, the code should be refactored >to not warn for unreferenced undefined symbols as my description says. Hi Fangrui, Sorry for the confusion, I did not mean to exactly mirror ignore_undef_symbol() in modpost. The conditions are different there and not all of them would not apply to kernel/module.c. Like __this_module, as you say, is not a problem as this will be resolved once all the module *.o are linked in the final .ko. So when it reaches the module loader it would no longer be UNDEF. I assume that it is a similar situation for the PPC64 symbols. What I meant that we could probably make this patch look nicer by moving the hardcoded check for "_GLOBAL_OFFSET_TABLE_" to a helper function ignore_undef_symbol(), similar to how modpost does it, without adding any additional conditions for now. And yes, if we ever need to extend this and refactor to not warn for unreferenced undefined symbols, we should refactor to generalize this case, but for the scope of this patch I think the suggested change is sufficient for now. Thank you, Jessica ^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH v2] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-14 21:18 ` Jessica Yu @ 2021-01-14 21:54 ` Fangrui Song 2021-01-14 22:01 ` Nick Desaulniers 2021-01-15 7:03 ` Marco Elver 2021-01-15 19:52 ` [PATCH v3] " Fangrui Song 1 sibling, 2 replies; 13+ messages in thread From: Fangrui Song @ 2021-01-14 21:54 UTC (permalink / raw) To: linux-kernel, Jessica Yu Cc: clang-built-linux, Sam Ravnborg, Fangrui Song, Marco Elver clang-12 -fno-pic (since https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` on x86. The two forms should have identical behaviors on x86-64 but the former causes GNU as<2.37 to produce an unreferenced undefined symbol _GLOBAL_OFFSET_TABLE_. (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the linker behavior is identical as far as Linux kernel is concerned.) Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for external function calls on x86. Note: ld -z defs and dynamic loaders do not error for unreferenced undefined symbols so the module loader is reading too much. If we ever need to ignore more symbols, the code should be refactored to ignore unreferenced symbols. Reported-by: Marco Elver <elver@google.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1250 Signed-off-by: Fangrui Song <maskray@google.com> --- kernel/module.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) --- Changes in v2: * Fix Marco's email address * Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol diff --git a/kernel/module.c b/kernel/module.c index 4bf30e4b3eaa..278f5129bde2 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2348,6 +2348,20 @@ static int verify_exported_symbols(struct module *mod) return 0; } +static int ignore_undef_symbol(Elf_Half emachine, const char *name) +{ + /* On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as + * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64. + * i386 has a similar problem but may not deserve a fix. + * + * If we ever have to ignore many symbols, consider refactoring the code to + * only warn if referenced by a relocation. + */ + if (emachine == EM_386 || emachine == EM_X86_64) + return !strcmp(name, "_GLOBAL_OFFSET_TABLE_"); + return 0; +} + /* Change all symbols so that st_value encodes the pointer directly. */ static int simplify_symbols(struct module *mod, const struct load_info *info) { @@ -2395,8 +2409,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) break; } - /* Ok if weak. */ - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) + /* Ok if weak or ignored. */ + if (!ksym && + (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || + ignore_undef_symbol(info->hdr->e_machine, name))) break; ret = PTR_ERR(ksym) ?: -ENOENT; -- 2.30.0.296.g2bfb1c46d8-goog ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH v2] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-14 21:54 ` [PATCH v2] " Fangrui Song @ 2021-01-14 22:01 ` Nick Desaulniers 2021-01-15 8:09 ` Jessica Yu 2021-01-15 7:03 ` Marco Elver 1 sibling, 1 reply; 13+ messages in thread From: Nick Desaulniers @ 2021-01-14 22:01 UTC (permalink / raw) To: Fangrui Song, Jessica Yu Cc: LKML, clang-built-linux, Sam Ravnborg, Marco Elver On Thu, Jan 14, 2021 at 1:54 PM 'Fangrui Song' via Clang Built Linux <clang-built-linux@googlegroups.com> wrote: > > clang-12 -fno-pic (since > https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) > can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` > on x86. The two forms should have identical behaviors on x86-64 but the > former causes GNU as<2.37 to produce an unreferenced undefined symbol > _GLOBAL_OFFSET_TABLE_. > > (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the > linker behavior is identical as far as Linux kernel is concerned.) > > Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what > scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the > problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for > external function calls on x86. > > Note: ld -z defs and dynamic loaders do not error for unreferenced > undefined symbols so the module loader is reading too much. If we ever > need to ignore more symbols, the code should be refactored to ignore > unreferenced symbols. > > Reported-by: Marco Elver <elver@google.com> > Link: https://github.com/ClangBuiltLinux/linux/issues/1250 > Signed-off-by: Fangrui Song <maskray@google.com> Thanks for the patch. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Jessica, would you mind adding when applying: Cc: <stable@vger.kernel.org> as I suspect we might want this fixed in stable tree's branches, too. It might of interest to add: Link: https://sourceware.org/bugzilla/show_bug.cgi?id=27178 too. > --- > kernel/module.c | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > --- > Changes in v2: > * Fix Marco's email address > * Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol > > diff --git a/kernel/module.c b/kernel/module.c > index 4bf30e4b3eaa..278f5129bde2 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -2348,6 +2348,20 @@ static int verify_exported_symbols(struct module *mod) > return 0; > } > > +static int ignore_undef_symbol(Elf_Half emachine, const char *name) > +{ > + /* On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as > + * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64. > + * i386 has a similar problem but may not deserve a fix. > + * > + * If we ever have to ignore many symbols, consider refactoring the code to > + * only warn if referenced by a relocation. > + */ > + if (emachine == EM_386 || emachine == EM_X86_64) > + return !strcmp(name, "_GLOBAL_OFFSET_TABLE_"); > + return 0; > +} > + > /* Change all symbols so that st_value encodes the pointer directly. */ > static int simplify_symbols(struct module *mod, const struct load_info *info) > { > @@ -2395,8 +2409,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) > break; > } > > - /* Ok if weak. */ > - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) > + /* Ok if weak or ignored. */ > + if (!ksym && > + (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || > + ignore_undef_symbol(info->hdr->e_machine, name))) > break; > > ret = PTR_ERR(ksym) ?: -ENOENT; > -- -- Thanks, ~Nick Desaulniers ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-14 22:01 ` Nick Desaulniers @ 2021-01-15 8:09 ` Jessica Yu 0 siblings, 0 replies; 13+ messages in thread From: Jessica Yu @ 2021-01-15 8:09 UTC (permalink / raw) To: Nick Desaulniers Cc: Fangrui Song, LKML, clang-built-linux, Sam Ravnborg, Marco Elver +++ Nick Desaulniers [14/01/21 14:01 -0800]: >On Thu, Jan 14, 2021 at 1:54 PM 'Fangrui Song' via Clang Built Linux ><clang-built-linux@googlegroups.com> wrote: >> >> clang-12 -fno-pic (since >> https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) >> can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` >> on x86. The two forms should have identical behaviors on x86-64 but the >> former causes GNU as<2.37 to produce an unreferenced undefined symbol >> _GLOBAL_OFFSET_TABLE_. >> >> (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the >> linker behavior is identical as far as Linux kernel is concerned.) >> >> Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what >> scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the >> problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for >> external function calls on x86. >> >> Note: ld -z defs and dynamic loaders do not error for unreferenced >> undefined symbols so the module loader is reading too much. If we ever >> need to ignore more symbols, the code should be refactored to ignore >> unreferenced symbols. >> >> Reported-by: Marco Elver <elver@google.com> >> Link: https://github.com/ClangBuiltLinux/linux/issues/1250 >> Signed-off-by: Fangrui Song <maskray@google.com> > >Thanks for the patch. > >Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > >Jessica, would you mind adding when applying: > >Cc: <stable@vger.kernel.org> > >as I suspect we might want this fixed in stable tree's branches, too. >It might of interest to add: > >Link: https://sourceware.org/bugzilla/show_bug.cgi?id=27178 > >too. Sure, will do! Thanks, Jessica ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-14 21:54 ` [PATCH v2] " Fangrui Song 2021-01-14 22:01 ` Nick Desaulniers @ 2021-01-15 7:03 ` Marco Elver 2021-01-15 8:14 ` Jessica Yu 2021-01-15 19:50 ` Fāng-ruì Sòng 1 sibling, 2 replies; 13+ messages in thread From: Marco Elver @ 2021-01-15 7:03 UTC (permalink / raw) To: Fangrui Song; +Cc: LKML, Jessica Yu, clang-built-linux, Sam Ravnborg On Thu, 14 Jan 2021 at 22:54, Fangrui Song <maskray@google.com> wrote: > clang-12 -fno-pic (since > https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) > can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` > on x86. The two forms should have identical behaviors on x86-64 but the > former causes GNU as<2.37 to produce an unreferenced undefined symbol > _GLOBAL_OFFSET_TABLE_. > > (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the > linker behavior is identical as far as Linux kernel is concerned.) > > Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what > scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the > problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for > external function calls on x86. > > Note: ld -z defs and dynamic loaders do not error for unreferenced > undefined symbols so the module loader is reading too much. If we ever > need to ignore more symbols, the code should be refactored to ignore > unreferenced symbols. > > Reported-by: Marco Elver <elver@google.com> > Link: https://github.com/ClangBuiltLinux/linux/issues/1250 > Signed-off-by: Fangrui Song <maskray@google.com> Tested-by: Marco Elver <elver@google.com> Thank you for the patch! > --- > kernel/module.c | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > --- > Changes in v2: > * Fix Marco's email address > * Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol > > diff --git a/kernel/module.c b/kernel/module.c > index 4bf30e4b3eaa..278f5129bde2 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -2348,6 +2348,20 @@ static int verify_exported_symbols(struct module *mod) > return 0; > } > > +static int ignore_undef_symbol(Elf_Half emachine, const char *name) Why not 'bool' return-type? > +{ > + /* On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as Not sure if checkpatch.pl warns about this, but this multi-line comment does not follow the normal kernel-style (see elsewhere in file): /* * ... */ > + * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64. > + * i386 has a similar problem but may not deserve a fix. > + * > + * If we ever have to ignore many symbols, consider refactoring the code to > + * only warn if referenced by a relocation. > + */ > + if (emachine == EM_386 || emachine == EM_X86_64) > + return !strcmp(name, "_GLOBAL_OFFSET_TABLE_"); > + return 0; > +} > + > /* Change all symbols so that st_value encodes the pointer directly. */ > static int simplify_symbols(struct module *mod, const struct load_info *info) > { > @@ -2395,8 +2409,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) > break; > } > > - /* Ok if weak. */ > - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) > + /* Ok if weak or ignored. */ > + if (!ksym && > + (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || > + ignore_undef_symbol(info->hdr->e_machine, name))) > break; > > ret = PTR_ERR(ksym) ?: -ENOENT; > -- > 2.30.0.296.g2bfb1c46d8-goog > ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-15 7:03 ` Marco Elver @ 2021-01-15 8:14 ` Jessica Yu 2021-01-15 19:50 ` Fāng-ruì Sòng 1 sibling, 0 replies; 13+ messages in thread From: Jessica Yu @ 2021-01-15 8:14 UTC (permalink / raw) To: Marco Elver; +Cc: Fangrui Song, LKML, clang-built-linux, Sam Ravnborg +++ Marco Elver [15/01/21 08:03 +0100]: >On Thu, 14 Jan 2021 at 22:54, Fangrui Song <maskray@google.com> wrote: >> clang-12 -fno-pic (since >> https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) >> can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` >> on x86. The two forms should have identical behaviors on x86-64 but the >> former causes GNU as<2.37 to produce an unreferenced undefined symbol >> _GLOBAL_OFFSET_TABLE_. >> >> (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the >> linker behavior is identical as far as Linux kernel is concerned.) >> >> Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what >> scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the >> problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for >> external function calls on x86. >> >> Note: ld -z defs and dynamic loaders do not error for unreferenced >> undefined symbols so the module loader is reading too much. If we ever >> need to ignore more symbols, the code should be refactored to ignore >> unreferenced symbols. >> >> Reported-by: Marco Elver <elver@google.com> >> Link: https://github.com/ClangBuiltLinux/linux/issues/1250 >> Signed-off-by: Fangrui Song <maskray@google.com> > >Tested-by: Marco Elver <elver@google.com> > >Thank you for the patch! > >> --- >> kernel/module.c | 20 ++++++++++++++++++-- >> 1 file changed, 18 insertions(+), 2 deletions(-) >> --- >> Changes in v2: >> * Fix Marco's email address >> * Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol >> >> diff --git a/kernel/module.c b/kernel/module.c >> index 4bf30e4b3eaa..278f5129bde2 100644 >> --- a/kernel/module.c >> +++ b/kernel/module.c >> @@ -2348,6 +2348,20 @@ static int verify_exported_symbols(struct module *mod) >> return 0; >> } >> >> +static int ignore_undef_symbol(Elf_Half emachine, const char *name) > >Why not 'bool' return-type? > >> +{ >> + /* On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as > >Not sure if checkpatch.pl warns about this, but this multi-line >comment does not follow the normal kernel-style (see elsewhere in >file): > >/* > * ... > */ +1 to Marco's comments. Otherwise, patch looks good to me. Thanks Fangrui! Jessica ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v2] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-15 7:03 ` Marco Elver 2021-01-15 8:14 ` Jessica Yu @ 2021-01-15 19:50 ` Fāng-ruì Sòng 1 sibling, 0 replies; 13+ messages in thread From: Fāng-ruì Sòng @ 2021-01-15 19:50 UTC (permalink / raw) To: Marco Elver; +Cc: LKML, Jessica Yu, clang-built-linux, Sam Ravnborg On Thu, Jan 14, 2021 at 11:04 PM Marco Elver <elver@google.com> wrote: > > On Thu, 14 Jan 2021 at 22:54, Fangrui Song <maskray@google.com> wrote: > > clang-12 -fno-pic (since > > https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) > > can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` > > on x86. The two forms should have identical behaviors on x86-64 but the > > former causes GNU as<2.37 to produce an unreferenced undefined symbol > > _GLOBAL_OFFSET_TABLE_. > > > > (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the > > linker behavior is identical as far as Linux kernel is concerned.) > > > > Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what > > scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the > > problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for > > external function calls on x86. > > > > Note: ld -z defs and dynamic loaders do not error for unreferenced > > undefined symbols so the module loader is reading too much. If we ever > > need to ignore more symbols, the code should be refactored to ignore > > unreferenced symbols. > > > > Reported-by: Marco Elver <elver@google.com> > > Link: https://github.com/ClangBuiltLinux/linux/issues/1250 > > Signed-off-by: Fangrui Song <maskray@google.com> > > Tested-by: Marco Elver <elver@google.com> > > Thank you for the patch! > > > --- > > kernel/module.c | 20 ++++++++++++++++++-- > > 1 file changed, 18 insertions(+), 2 deletions(-) > > --- > > Changes in v2: > > * Fix Marco's email address > > * Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol > > > > diff --git a/kernel/module.c b/kernel/module.c > > index 4bf30e4b3eaa..278f5129bde2 100644 > > --- a/kernel/module.c > > +++ b/kernel/module.c > > @@ -2348,6 +2348,20 @@ static int verify_exported_symbols(struct module *mod) > > return 0; > > } > > > > +static int ignore_undef_symbol(Elf_Half emachine, const char *name) > > Why not 'bool' return-type? Will use bool and false in v3. > > +{ > > + /* On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as > > Not sure if checkpatch.pl warns about this, but this multi-line > comment does not follow the normal kernel-style (see elsewhere in > file): It doesn't warn about this. (The commit description warning cannot be fixed, even if I place the closing paren on the next line.) % ./scripts/checkpatch.pl v2-0001-module-Ignore-_GLOBAL_OFFSET_TABLE_-when-warning-.patch WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line) #8: https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) total: 0 errors, 1 warnings, 32 lines checked NOTE: For some of the reported defects, checkpatch may be able to mechanically convert to the typical style using --fix or --fix-inplace. v2-0001-module-Ignore-_GLOBAL_OFFSET_TABLE_-when-warning-.patch has style problems, please review. NOTE: If any of the errors are false positives, please report them to the maintainer, see CHECKPATCH in MAINTAINERS. > /* > * ... > */ > > > + * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64. > > + * i386 has a similar problem but may not deserve a fix. > > + * > > + * If we ever have to ignore many symbols, consider refactoring the code to > > + * only warn if referenced by a relocation. > > + */ > > + if (emachine == EM_386 || emachine == EM_X86_64) > > + return !strcmp(name, "_GLOBAL_OFFSET_TABLE_"); > > + return 0; > > +} > > + > > /* Change all symbols so that st_value encodes the pointer directly. */ > > static int simplify_symbols(struct module *mod, const struct load_info *info) > > { > > @@ -2395,8 +2409,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) > > break; > > } > > > > - /* Ok if weak. */ > > - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) > > + /* Ok if weak or ignored. */ > > + if (!ksym && > > + (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || > > + ignore_undef_symbol(info->hdr->e_machine, name))) > > break; > > > > ret = PTR_ERR(ksym) ?: -ENOENT; > > -- > > 2.30.0.296.g2bfb1c46d8-goog > > -- 宋方睿 ^ permalink raw reply [flat|nested] 13+ messages in thread
* [PATCH v3] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-14 21:18 ` Jessica Yu 2021-01-14 21:54 ` [PATCH v2] " Fangrui Song @ 2021-01-15 19:52 ` Fangrui Song 2021-01-15 19:55 ` Nathan Chancellor 2021-01-18 10:14 ` Jessica Yu 1 sibling, 2 replies; 13+ messages in thread From: Fangrui Song @ 2021-01-15 19:52 UTC (permalink / raw) To: linux-kernel, Jessica Yu Cc: clang-built-linux, Sam Ravnborg, Fangrui Song, Marco Elver, Nick Desaulniers, stable clang-12 -fno-pic (since https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` on x86. The two forms should have identical behaviors on x86-64 but the former causes GNU as<2.37 to produce an unreferenced undefined symbol _GLOBAL_OFFSET_TABLE_. (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the linker behavior is identical as far as Linux kernel is concerned.) Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for external function calls on x86. Note: ld -z defs and dynamic loaders do not error for unreferenced undefined symbols so the module loader is reading too much. If we ever need to ignore more symbols, the code should be refactored to ignore unreferenced symbols. Reported-by: Marco Elver <elver@google.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1250 Signed-off-by: Fangrui Song <maskray@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Marco Elver <elver@google.com> Cc: <stable@vger.kernel.org> --- Changes in v2: * Fix Marco's email address * Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol --- Changes in v3: * Fix the style of a multi-line comment. * Use static bool ignore_undef_symbol. --- kernel/module.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 4bf30e4b3eaa..805c49d1b86d 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2348,6 +2348,21 @@ static int verify_exported_symbols(struct module *mod) return 0; } +static bool ignore_undef_symbol(Elf_Half emachine, const char *name) +{ + /* + * On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as + * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64. + * i386 has a similar problem but may not deserve a fix. + * + * If we ever have to ignore many symbols, consider refactoring the code to + * only warn if referenced by a relocation. + */ + if (emachine == EM_386 || emachine == EM_X86_64) + return !strcmp(name, "_GLOBAL_OFFSET_TABLE_"); + return false; +} + /* Change all symbols so that st_value encodes the pointer directly. */ static int simplify_symbols(struct module *mod, const struct load_info *info) { @@ -2395,8 +2410,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) break; } - /* Ok if weak. */ - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) + /* Ok if weak or ignored. */ + if (!ksym && + (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || + ignore_undef_symbol(info->hdr->e_machine, name))) break; ret = PTR_ERR(ksym) ?: -ENOENT; -- 2.30.0.296.g2bfb1c46d8-goog ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH v3] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-15 19:52 ` [PATCH v3] " Fangrui Song @ 2021-01-15 19:55 ` Nathan Chancellor 2021-01-18 10:14 ` Jessica Yu 1 sibling, 0 replies; 13+ messages in thread From: Nathan Chancellor @ 2021-01-15 19:55 UTC (permalink / raw) To: Fangrui Song Cc: linux-kernel, Jessica Yu, clang-built-linux, Sam Ravnborg, Marco Elver, Nick Desaulniers, stable On Fri, Jan 15, 2021 at 11:52:22AM -0800, 'Fangrui Song' via Clang Built Linux wrote: > clang-12 -fno-pic (since > https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) > can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` > on x86. The two forms should have identical behaviors on x86-64 but the > former causes GNU as<2.37 to produce an unreferenced undefined symbol > _GLOBAL_OFFSET_TABLE_. > > (On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the > linker behavior is identical as far as Linux kernel is concerned.) > > Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what > scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the > problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for > external function calls on x86. > > Note: ld -z defs and dynamic loaders do not error for unreferenced > undefined symbols so the module loader is reading too much. If we ever > need to ignore more symbols, the code should be refactored to ignore > unreferenced symbols. > > Reported-by: Marco Elver <elver@google.com> > Link: https://github.com/ClangBuiltLinux/linux/issues/1250 > Signed-off-by: Fangrui Song <maskray@google.com> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Tested-by: Marco Elver <elver@google.com> > Cc: <stable@vger.kernel.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > > --- > Changes in v2: > * Fix Marco's email address > * Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol > --- > Changes in v3: > * Fix the style of a multi-line comment. > * Use static bool ignore_undef_symbol. > --- > kernel/module.c | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/kernel/module.c b/kernel/module.c > index 4bf30e4b3eaa..805c49d1b86d 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -2348,6 +2348,21 @@ static int verify_exported_symbols(struct module *mod) > return 0; > } > > +static bool ignore_undef_symbol(Elf_Half emachine, const char *name) > +{ > + /* > + * On x86, PIC code and Clang non-PIC code may have call foo@PLT. GNU as > + * before 2.37 produces an unreferenced _GLOBAL_OFFSET_TABLE_ on x86-64. > + * i386 has a similar problem but may not deserve a fix. > + * > + * If we ever have to ignore many symbols, consider refactoring the code to > + * only warn if referenced by a relocation. > + */ > + if (emachine == EM_386 || emachine == EM_X86_64) > + return !strcmp(name, "_GLOBAL_OFFSET_TABLE_"); > + return false; > +} > + > /* Change all symbols so that st_value encodes the pointer directly. */ > static int simplify_symbols(struct module *mod, const struct load_info *info) > { > @@ -2395,8 +2410,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info) > break; > } > > - /* Ok if weak. */ > - if (!ksym && ELF_ST_BIND(sym[i].st_info) == STB_WEAK) > + /* Ok if weak or ignored. */ > + if (!ksym && > + (ELF_ST_BIND(sym[i].st_info) == STB_WEAK || > + ignore_undef_symbol(info->hdr->e_machine, name))) > break; > > ret = PTR_ERR(ksym) ?: -ENOENT; > -- > 2.30.0.296.g2bfb1c46d8-goog > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210115195222.3453262-1-maskray%40google.com. ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH v3] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols 2021-01-15 19:52 ` [PATCH v3] " Fangrui Song 2021-01-15 19:55 ` Nathan Chancellor @ 2021-01-18 10:14 ` Jessica Yu 1 sibling, 0 replies; 13+ messages in thread From: Jessica Yu @ 2021-01-18 10:14 UTC (permalink / raw) To: Fangrui Song Cc: linux-kernel, clang-built-linux, Sam Ravnborg, Marco Elver, Nick Desaulniers, stable +++ Fangrui Song [15/01/21 11:52 -0800]: >clang-12 -fno-pic (since >https://github.com/llvm/llvm-project/commit/a084c0388e2a59b9556f2de0083333232da3f1d6) >can emit `call __stack_chk_fail@PLT` instead of `call __stack_chk_fail` >on x86. The two forms should have identical behaviors on x86-64 but the >former causes GNU as<2.37 to produce an unreferenced undefined symbol >_GLOBAL_OFFSET_TABLE_. > >(On x86-32, there is an R_386_PC32 vs R_386_PLT32 difference but the >linker behavior is identical as far as Linux kernel is concerned.) > >Simply ignore _GLOBAL_OFFSET_TABLE_ for now, like what >scripts/mod/modpost.c:ignore_undef_symbol does. This also fixes the >problem for gcc/clang -fpie and -fpic, which may emit `call foo@PLT` for >external function calls on x86. > >Note: ld -z defs and dynamic loaders do not error for unreferenced >undefined symbols so the module loader is reading too much. If we ever >need to ignore more symbols, the code should be refactored to ignore >unreferenced symbols. > >Reported-by: Marco Elver <elver@google.com> >Link: https://github.com/ClangBuiltLinux/linux/issues/1250 >Signed-off-by: Fangrui Song <maskray@google.com> >Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> >Tested-by: Marco Elver <elver@google.com> >Cc: <stable@vger.kernel.org> > >--- >Changes in v2: >* Fix Marco's email address >* Add a function ignore_undef_symbol similar to scripts/mod/modpost.c:ignore_undef_symbol >--- >Changes in v3: >* Fix the style of a multi-line comment. >* Use static bool ignore_undef_symbol. Patch has been queued up on modules-next: https://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux.git/commit/?h=modules-next&id=ebfac7b778fac8b0e8e92ec91d0b055f046b4604 Thanks! Jessica ^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2021-01-18 10:25 UTC | newest] Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-01-14 5:48 [PATCH] module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols Fangrui Song 2021-01-14 14:06 ` Jessica Yu 2021-01-14 16:57 ` Fāng-ruì Sòng 2021-01-14 21:18 ` Jessica Yu 2021-01-14 21:54 ` [PATCH v2] " Fangrui Song 2021-01-14 22:01 ` Nick Desaulniers 2021-01-15 8:09 ` Jessica Yu 2021-01-15 7:03 ` Marco Elver 2021-01-15 8:14 ` Jessica Yu 2021-01-15 19:50 ` Fāng-ruì Sòng 2021-01-15 19:52 ` [PATCH v3] " Fangrui Song 2021-01-15 19:55 ` Nathan Chancellor 2021-01-18 10:14 ` Jessica Yu
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