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f534255e4d
This patch consolidate the Linux vDSO define and usage across all ports
that uses it. The common vDSO definitions and calling through
{INLINE/INTERNAL}_VSYSCALL macros are moved to a common header
sysdep-vdso.h and vDSO name declaration and prototype is defined
using a common macro.
Also PTR_{MANGLE,DEMANGLE} is added to ports that does not use them
for vDSO calls (aarch64, powerpc, s390, and tile) and thus it will
reflect in code changes. For ports that already implement pointer
mangling/demangling in vDSO system (i386, x32, x86_64) this patch
is mainly a code refactor.
Checked on x32, x86_64, x32, ppc64le, and aarch64.
75 lines
3.3 KiB
C
75 lines
3.3 KiB
C
/* Resolve function pointers to VDSO functions.
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Copyright (C) 2005-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _LIBC_VDSO_H
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#define _LIBC_VDSO_H
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#ifdef SHARED
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#include <sysdep-vdso.h>
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extern int (*VDSO_SYMBOL(gettimeofday)) (struct timeval *, void *)
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attribute_hidden;
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extern int (*VDSO_SYMBOL(clock_gettime)) (clockid_t, struct timespec *);
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extern int (*VDSO_SYMBOL(clock_getres)) (clockid_t, struct timespec *);
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extern unsigned long long (*VDSO_SYMBOL(get_tbfreq)) (void);
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extern int (*VDSO_SYMBOL(getcpu)) (unsigned *, unsigned *);
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extern time_t (*VDSO_SYMBOL(time)) (time_t *);
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#if defined(__PPC64__) || defined(__powerpc64__)
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extern void *VDSO_SYMBOL(sigtramp_rt64);
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#else
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extern void *VDSO_SYMBOL(sigtramp32);
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extern void *VDSO_SYMBOL(sigtramp_rt32);
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#endif
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#if (defined(__PPC64__) || defined(__powerpc64__)) && _CALL_ELF != 2
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/* The correct solution is for _dl_vdso_vsym to return the address of the OPD
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for the kernel VDSO function. That address would then be stored in the
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__vdso_* variables and returned as the result of the IFUNC resolver function.
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Yet, the kernel does not contain any OPD entries for the VDSO functions
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(incomplete implementation). However, PLT relocations for IFUNCs still expect
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the address of an OPD to be returned from the IFUNC resolver function (since
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PLT entries on PPC64 are just copies of OPDs). The solution for now is to
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create an artificial static OPD for each VDSO function returned by a resolver
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function. The TOC value is set to a non-zero value to avoid triggering lazy
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symbol resolution via .glink0/.plt0 for a zero TOC (requires thread-safe PLT
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sequences) when the dynamic linker isn't prepared for it e.g. RTLD_NOW. None
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of the kernel VDSO routines use the TOC or AUX values so any non-zero value
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will work. Note that function pointer comparisons will not use this artificial
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static OPD since those are resolved via ADDR64 relocations and will point at
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the non-IFUNC default OPD for the symbol. Lastly, because the IFUNC relocations
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are processed immediately at startup the resolver functions and this code need
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not be thread-safe, but if the caller writes to a PLT slot it must do so in a
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thread-safe manner with all the required barriers. */
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#define VDSO_IFUNC_RET(value) \
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({ \
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static Elf64_FuncDesc vdso_opd = { .fd_toc = ~0x0 }; \
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vdso_opd.fd_func = (Elf64_Addr)value; \
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&vdso_opd; \
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})
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#else
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#define VDSO_IFUNC_RET(value) ((void *) (value))
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#endif
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#endif
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#endif /* _LIBC_VDSO_H */
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