| /* Resolve function pointers to VDSO functions. |
| Copyright (C) 2005-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| |
| #ifndef _LIBC_VDSO_H |
| #define _LIBC_VDSO_H |
| |
| #ifdef SHARED |
| |
| extern void *__vdso_gettimeofday attribute_hidden; |
| |
| extern void *__vdso_clock_gettime; |
| |
| extern void *__vdso_clock_getres; |
| |
| extern void *__vdso_get_tbfreq; |
| |
| extern void *__vdso_getcpu; |
| |
| extern void *__vdso_time; |
| |
| #if defined(__PPC64__) || defined(__powerpc64__) |
| extern void *__vdso_sigtramp_rt64; |
| #else |
| extern void *__vdso_sigtramp32; |
| extern void *__vdso_sigtramp_rt32; |
| #endif |
| |
| #if (defined(__PPC64__) || defined(__powerpc64__)) && _CALL_ELF != 2 |
| /* The correct solution is for _dl_vdso_vsym to return the address of the OPD |
| for the kernel VDSO function. That address would then be stored in the |
| __vdso_* variables and returned as the result of the IFUNC resolver function. |
| Yet, the kernel does not contain any OPD entries for the VDSO functions |
| (incomplete implementation). However, PLT relocations for IFUNCs still expect |
| the address of an OPD to be returned from the IFUNC resolver function (since |
| PLT entries on PPC64 are just copies of OPDs). The solution for now is to |
| create an artificial static OPD for each VDSO function returned by a resolver |
| function. The TOC value is set to a non-zero value to avoid triggering lazy |
| symbol resolution via .glink0/.plt0 for a zero TOC (requires thread-safe PLT |
| sequences) when the dynamic linker isn't prepared for it e.g. RTLD_NOW. None |
| of the kernel VDSO routines use the TOC or AUX values so any non-zero value |
| will work. Note that function pointer comparisons will not use this artificial |
| static OPD since those are resolved via ADDR64 relocations and will point at |
| the non-IFUNC default OPD for the symbol. Lastly, because the IFUNC relocations |
| are processed immediately at startup the resolver functions and this code need |
| not be thread-safe, but if the caller writes to a PLT slot it must do so in a |
| thread-safe manner with all the required barriers. */ |
| #define VDSO_IFUNC_RET(value) \ |
| ({ \ |
| static Elf64_FuncDesc vdso_opd = { .fd_toc = ~0x0 }; \ |
| vdso_opd.fd_func = (Elf64_Addr)value; \ |
| &vdso_opd; \ |
| }) |
| |
| #else |
| #define VDSO_IFUNC_RET(value) ((void *) (value)) |
| #endif |
| |
| #endif |
| |
| #endif /* _LIBC_VDSO_H */ |
