74 lines
2.3 KiB
Diff
74 lines
2.3 KiB
Diff
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commit f06f3f05b48c72e2c9b0fa78671f94fd22d67da8
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Wed Jun 1 07:14:42 2016 +0200
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fork in libpthread cannot use IFUNC resolver [BZ #19861]
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This commit only addresses the fork case, the vfork case has to be a
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tail call, which is why the generic code needs an IFUNC resolver
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there.
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diff --git a/nptl/pt-fork.c b/nptl/pt-fork.c
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index b65d6b4..db9b61d 100644
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--- a/nptl/pt-fork.c
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+++ b/nptl/pt-fork.c
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@@ -25,33 +25,14 @@
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the historical ABI requires it. For static linking, there is no need to
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provide anything here--the libc version will be linked in. For shared
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library ABI compatibility, there must be __fork and fork symbols in
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- libpthread.so; so we define them using IFUNC to redirect to the libc
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- function. */
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+ libpthread.so.
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-#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
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-
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-# if HAVE_IFUNC
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-
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-static __typeof (fork) *
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-__attribute__ ((used))
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-fork_resolve (void)
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-{
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- return &__libc_fork;
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-}
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+ With an IFUNC resolver, it would be possible to avoid the
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+ indirection, but the IFUNC resolver might run before the
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+ __libc_fork symbol has been relocated, in which case the IFUNC
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+ resolver would not be able to provide the correct address. */
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-# ifdef HAVE_ASM_SET_DIRECTIVE
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-# define DEFINE_FORK(name) \
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- asm (".set " #name ", fork_resolve\n" \
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- ".globl " #name "\n" \
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- ".type " #name ", %gnu_indirect_function");
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-# else
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-# define DEFINE_FORK(name) \
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- asm (#name " = fork_resolve\n" \
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- ".globl " #name "\n" \
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- ".type " #name ", %gnu_indirect_function");
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-# endif
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-
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-# else /* !HAVE_IFUNC */
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+#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
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static pid_t __attribute__ ((used))
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fork_compat (void)
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@@ -59,14 +40,10 @@ fork_compat (void)
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return __libc_fork ();
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}
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-# define DEFINE_FORK(name) strong_alias (fork_compat, name)
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-
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-# endif /* HAVE_IFUNC */
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-
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-DEFINE_FORK (fork_ifunc)
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-compat_symbol (libpthread, fork_ifunc, fork, GLIBC_2_0);
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+strong_alias (fork_compat, fork_alias)
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+compat_symbol (libpthread, fork_alias, fork, GLIBC_2_0);
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-DEFINE_FORK (__fork_ifunc)
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-compat_symbol (libpthread, __fork_ifunc, __fork, GLIBC_2_0);
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+strong_alias (fork_compat, __fork_alias)
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+compat_symbol (libpthread, __fork_alias, __fork, GLIBC_2_0);
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#endif
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