From 4e17c78e4a5da41b3cfefdd49ab760b051b65029 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Thu, 12 Oct 2017 16:24:44 -0300 Subject: Add common ifunc-init.h header This patch moves the generic definition from x86_64 init-arch to a common header ifunc-init.h. No functional changes is expected. Checked on a x86_64-linux-gnu build. * sysdeps/generic/ifunc-init.h: New file. * sysdeps/x86/init-arch.h: Use generic ifunc-init.h. --- sysdeps/generic/ifunc-init.h | 54 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 sysdeps/generic/ifunc-init.h (limited to 'sysdeps/generic/ifunc-init.h') diff --git a/sysdeps/generic/ifunc-init.h b/sysdeps/generic/ifunc-init.h new file mode 100644 index 0000000000..59d5ac6c1c --- /dev/null +++ b/sysdeps/generic/ifunc-init.h @@ -0,0 +1,54 @@ +/* IFUNC generic definitions. + This file is part of the GNU C Library. + Copyright (C) 2017 Free Software Foundation, Inc. + + 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 + . */ + +/* These macros are used to implement ifunc selection in C. To implement + an ifunc function, foo, which returns the address of __foo_impl1 or + __foo_impl2: + + #define foo __redirect_foo + #include + #undef foo + #define SYMBOL_NAME foo + #include + + extern __typeof (REDIRECT_NAME) OPTIMIZE (impl1) attribute_hidden; + extern __typeof (REDIRECT_NAME) OPTIMIZE (impl2) attribute_hidden; + + static inline void * + foo_selector (void) + { + if (condition) + return OPTIMIZE (impl2); + + return OPTIMIZE (impl1); + } + + libc_ifunc_redirected (__redirect_foo, foo, IFUNC_SELECTOR ()); +*/ + +#define PASTER1(x,y) x##_##y +#define EVALUATOR1(x,y) PASTER1 (x,y) +#define PASTER2(x,y) __##x##_##y +#define EVALUATOR2(x,y) PASTER2 (x,y) + +/* Basically set '__redirect_' to use as type definition, + '___' as the optimized implementation and + '_ifunc_selector' as the IFUNC selector. */ +#define REDIRECT_NAME EVALUATOR1 (__redirect, SYMBOL_NAME) +#define OPTIMIZE(name) EVALUATOR2 (SYMBOL_NAME, name) +#define IFUNC_SELECTOR EVALUATOR1 (SYMBOL_NAME, ifunc_selector) -- cgit 1.4.1