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 <evan@rivosinc.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

1 files changed, 27 insertions, 0 deletions

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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+#include <ifunc-init.h>
+#include <sys/hwprobe.h>
+
+#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)