From a29bb320a1a1daa8add4d213fc70f273810dd91a Mon Sep 17 00:00:00 2001 From: Evan Green Date: Tue, 27 Feb 2024 14:56:41 -0800 Subject: [PATCH] riscv: Enable multi-arg ifunc resolvers RISC-V is apparently the first architecture to pass more than one argument to ifunc resolvers. The helper macros in libc-symbols.h, __ifunc_resolver(), __ifunc(), and __ifunc_hidden(), are incompatible with this. These macros have an "arg" (non-final) parameter that represents the parameter signature of the ifunc resolver. The result is an inability to pass the required comma through in a single preprocessor argument. Rearrange the __ifunc_resolver() macro to be variadic, and pass the types as those variable parameters. Move the guts of __ifunc() and __ifunc_hidden() into new macros, __ifunc_args(), and __ifunc_args_hidden(), that pass the variable arguments down through to __ifunc_resolver(). Then redefine __ifunc() and __ifunc_hidden(), which are used in a bunch of places, to simply shuffle the arguments down into __ifunc_args[_hidden]. Finally, define a riscv-ifunc.h header, which provides convenience macros to those looking to write ifunc selectors that use both arguments. Signed-off-by: Evan Green Reviewed-by: Florian Weimer Signed-off-by: Palmer Dabbelt --- include/libc-symbols.h | 28 +++++++++++++++++----------- sysdeps/riscv/riscv-ifunc.h | 27 +++++++++++++++++++++++++++ 2 files changed, 44 insertions(+), 11 deletions(-) create mode 100644 sysdeps/riscv/riscv-ifunc.h diff --git a/include/libc-symbols.h b/include/libc-symbols.h index e21bb599b3..4367aa6740 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -667,9 +667,9 @@ for linking") #endif /* Helper / base macros for indirect function symbols. */ -#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \ +#define __ifunc_resolver(type_name, name, expr, init, classifier, ...) \ classifier inhibit_stack_protector \ - __typeof (type_name) *name##_ifunc (arg) \ + __typeof (type_name) *name##_ifunc (__VA_ARGS__) \ { \ init (); \ __typeof (type_name) *res = expr; \ @@ -677,13 +677,13 @@ for linking") } #ifdef HAVE_GCC_IFUNC -# define __ifunc(type_name, name, expr, arg, init) \ +# define __ifunc_args(type_name, name, expr, init, ...) \ extern __typeof (type_name) name __attribute__ \ ((ifunc (#name "_ifunc"))); \ - __ifunc_resolver (type_name, name, expr, arg, init, static) + __ifunc_resolver (type_name, name, expr, init, static, __VA_ARGS__) -# define __ifunc_hidden(type_name, name, expr, arg, init) \ - __ifunc (type_name, name, expr, arg, init) +# define __ifunc_args_hidden(type_name, name, expr, init, ...) \ + __ifunc_args (type_name, name, expr, init, __VA_ARGS__) #else /* Gcc does not support __attribute__ ((ifunc (...))). Use the old behaviour as fallback. But keep in mind that the debug information for the ifunc @@ -694,18 +694,24 @@ for linking") different signatures. (Gcc support is disabled at least on a ppc64le Ubuntu 14.04 system.) */ -# define __ifunc(type_name, name, expr, arg, init) \ +# define __ifunc_args(type_name, name, expr, init, ...) \ extern __typeof (type_name) name; \ - __typeof (type_name) *name##_ifunc (arg) __asm__ (#name); \ - __ifunc_resolver (type_name, name, expr, arg, init,) \ + __typeof (type_name) *name##_ifunc (__VA_ARGS__) __asm__ (#name); \ + __ifunc_resolver (type_name, name, expr, init, , __VA_ARGS__) \ __asm__ (".type " #name ", %gnu_indirect_function"); -# define __ifunc_hidden(type_name, name, expr, arg, init) \ +# define __ifunc_args_hidden(type_name, name, expr, init, ...) \ extern __typeof (type_name) __libc_##name; \ - __ifunc (type_name, __libc_##name, expr, arg, init) \ + __ifunc (type_name, __libc_##name, expr, __VA_ARGS__, init) \ strong_alias (__libc_##name, name); #endif /* !HAVE_GCC_IFUNC */ +#define __ifunc(type_name, name, expr, arg, init) \ + __ifunc_args (type_name, name, expr, init, arg) + +#define __ifunc_hidden(type_name, name, expr, arg, init) \ + __ifunc_args_hidden (type_name, name, expr, init, arg) + /* The following macros are used for indirect function symbols in libc.so. First of all, you need to have the function prototyped somewhere, say in foo.h: diff --git a/sysdeps/riscv/riscv-ifunc.h b/sysdeps/riscv/riscv-ifunc.h new file mode 100644 index 0000000000..c77ab51548 --- /dev/null +++ b/sysdeps/riscv/riscv-ifunc.h @@ -0,0 +1,27 @@ +/* Common definition for ifunc resolvers. Linux/RISC-V version. + This file is part of the GNU C Library. + Copyright (C) 2024 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 + . */ + +#include +#include +#include + +#define INIT_ARCH() + +#define riscv_libc_ifunc(name, expr) \ + __ifunc_args (name, name, expr(hwcap, hwprobe), INIT_ARCH, \ + uint64_t hwcap, __riscv_hwprobe_t hwprobe)