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From: Fangrui Song <maskray@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/google/grte/v5-2.27/master] Use libc_hidden_* for fputs (bug 15105). Date: Fri, 19 Nov 2021 21:21:47 +0000 (GMT) [thread overview] Message-ID: <20211119212147.61E0D3858424@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d7c1214f4d417119c4cca5c36c2adfc4d83be8fc commit d7c1214f4d417119c4cca5c36c2adfc4d83be8fc Author: Joseph Myers <joseph@codesourcery.com> Date: Thu Feb 15 20:58:16 2018 +0000 Use libc_hidden_* for fputs (bug 15105). Among other localplt test failures when building with -Os, there are libc.so PLT references for fputs. fputs calls normally get redirected to _IO_fputs by a macro in include/stdio.h (and _IO_fputs in turn uses libc_hidden_proto), but GCC can convert an fprintf call with a constant string argument into an fputs call, which of course is then unaffected by the macro redirection. (I don't know why this issue only appears with -Os.) This patch duly adds a use of libc_hidden_proto for fputs. I see no obvious reason why the fputs macro redirection is needed at all, but this patch does not change it. Tested for x86_64 (both that it removes this particular localplt failure for -Os - but other such failures remain so the bug can't yet be closed - and that the testsuite continues to pass without -Os). [BZ #15105] * include/stdio.h [!_ISOMAC && IS_IN (libc)] (fputs): Use libc_hidden_proto. * libio/iofputs.c (fputs): Use libc_hidden_weak. (cherry picked from commit 499b315324519f8deb5b42a143a76319934a3ab0) Diff: --- include/stdio.h | 4 ++++ libio/iofputs.c | 1 + 2 files changed, 5 insertions(+) diff --git a/include/stdio.h b/include/stdio.h index f1e987ae5e..6759ed3fb1 100644 --- a/include/stdio.h +++ b/include/stdio.h @@ -135,6 +135,10 @@ extern int _IO_new_fclose (_IO_FILE*); # define fclose(fp) _IO_new_fclose (fp) extern int _IO_fputs (const char*, _IO_FILE*); libc_hidden_proto (_IO_fputs) +/* The compiler may optimize calls to fprintf into calls to fputs. + Use libc_hidden_proto to ensure that those calls, not redirected by + the fputs macro, also do not go through the PLT. */ +libc_hidden_proto (fputs) # define fputs(str, fp) _IO_fputs (str, fp) extern int _IO_new_fsetpos (_IO_FILE *, const _IO_fpos_t *); # define fsetpos(fp, posp) _IO_new_fsetpos (fp, posp) diff --git a/libio/iofputs.c b/libio/iofputs.c index b4fbeb5e60..176e9ed281 100644 --- a/libio/iofputs.c +++ b/libio/iofputs.c @@ -43,6 +43,7 @@ _IO_fputs (const char *str, _IO_FILE *fp) libc_hidden_def (_IO_fputs) weak_alias (_IO_fputs, fputs) +libc_hidden_weak (fputs) # ifndef _IO_MTSAFE_IO strong_alias (_IO_fputs, __fputs_unlocked)
next reply other threads:[~2021-11-19 21:21 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-11-19 21:21 Fangrui Song [this message] -- strict thread matches above, loose matches on Subject: below -- 2021-11-15 22:40 Fangrui Song
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