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From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: libc-alpha@sourceware.org
Subject: [PATCH v5 4/7] csu: Avoid weak ref for __ehdr_start in static PIE
Date: Wed, 20 Jan 2021 15:31:05 +0000	[thread overview]
Message-ID: <4da71cb981057048e8cf9dec8731ad936b433e38.1611155254.git.szabolcs.nagy@arm.com> (raw)
In-Reply-To: <cover.1611155254.git.szabolcs.nagy@arm.com>

All linkers support __ehdr_start that support static PIE linking,
so there is no need to check for its presence via a weak reference.

This avoids a RELATIVE relocation in static PIE startup code on some
targets.

With non-PIE static linking the weak ref check is kept in case the
linker does not support __ehdr_start.
---
 csu/libc-start.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/csu/libc-start.c b/csu/libc-start.c
index db859c3bed..5b9ce1d158 100644
--- a/csu/libc-start.c
+++ b/csu/libc-start.c
@@ -175,8 +175,12 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
          information from auxv.  */
 
       extern const ElfW(Ehdr) __ehdr_start
+# if BUILD_PIE_DEFAULT
+	__attribute__ ((visibility ("hidden")));
+# else
 	__attribute__ ((weak, visibility ("hidden")));
       if (&__ehdr_start != NULL)
+# endif
         {
           assert (__ehdr_start.e_phentsize == sizeof *GL(dl_phdr));
           GL(dl_phdr) = (const void *) &__ehdr_start + __ehdr_start.e_phoff;
-- 
2.17.1


  parent reply	other threads:[~2021-01-20 15:31 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-20 15:29 [PATCH v5 0/7] fix ifunc with static pie [BZ #27072] Szabolcs Nagy
2021-01-20 15:30 ` [PATCH v5 1/7] elf: Make the tunable struct definition internal only Szabolcs Nagy
2021-01-20 15:30 ` [PATCH v5 2/7] elf: Avoid RELATIVE relocs in __tunables_init Szabolcs Nagy
2021-01-20 15:30 ` [PATCH v5 3/7] configure: Check for static PIE support Szabolcs Nagy
2021-01-21 13:59   ` Adhemerval Zanella
2021-01-20 15:31 ` Szabolcs Nagy [this message]
2021-01-20 15:36   ` [PATCH v5 4/7] csu: Avoid weak ref for __ehdr_start in static PIE H.J. Lu
2021-01-21 14:01   ` Adhemerval Zanella
2021-01-20 15:31 ` [PATCH v5 5/7] Use hidden visibility for early static PIE code Szabolcs Nagy
2021-01-21 14:04   ` Adhemerval Zanella
2021-01-20 15:31 ` [PATCH v5 6/7] csu: Move static pie self relocation later [BZ #27072] Szabolcs Nagy
2021-01-21 14:07   ` Adhemerval Zanella
2021-01-21 15:38     ` Szabolcs Nagy
2021-01-20 15:31 ` [PATCH v5 7/7] Make libc symbols hidden in static PIE Szabolcs Nagy
2021-01-21 14:10   ` Adhemerval Zanella
2021-01-21 15:44     ` Szabolcs Nagy
2021-01-22  1:25   ` Tulio Magno Quites Machado Filho
2021-01-22  9:41     ` Szabolcs Nagy
2021-01-27  9:44   ` Andreas Schwab

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