From: Yury Khrustalev Date: Thu, 24 Apr 2025 15:58:46 +0000 (+0100) Subject: aarch64: add __ifunc_hwcap function to be used in ifunc resolvers X-Git-Tag: glibc-2.42~157 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fcd6a8b5c53a5fbd847aec6fa8d36a71388441c8;p=thirdparty%2Fglibc.git aarch64: add __ifunc_hwcap function to be used in ifunc resolvers Add a new helper function __ifunc_hwcap() as a portable way to access HWCAP elements via the parameter(s) passed to an ifunc resolver checking the _IFUNC_ARG_HWCAP bit in the first parameter and size of the buffer in the second parameter. Note that 0 is returned when the requested element is not available or does not correspond to a valid AT_HWCAP{,2,...} value. Also add relevant tests. Reviewed-by: Adhemerval Zanella --- diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile index 0fc6cf1693..021a35682b 100644 --- a/sysdeps/aarch64/Makefile +++ b/sysdeps/aarch64/Makefile @@ -41,7 +41,12 @@ gen-as-const-headers += \ dl-link.sym \ rtld-global-offsets.sym -tests-internal += tst-ifunc-arg-1 tst-ifunc-arg-2 +tests-internal += \ + tst-ifunc-arg-1 \ + tst-ifunc-arg-2 \ + tst-ifunc-arg-3 \ + tst-ifunc-arg-4 \ + #tests-internal tests += tst-vpcs modules-names += tst-vpcs-mod diff --git a/sysdeps/aarch64/sys/ifunc.h b/sysdeps/aarch64/sys/ifunc.h index 42d173195f..a3322a9cfc 100644 --- a/sysdeps/aarch64/sys/ifunc.h +++ b/sysdeps/aarch64/sys/ifunc.h @@ -19,6 +19,8 @@ #ifndef _SYS_IFUNC_H #define _SYS_IFUNC_H +#include + /* A second argument is passed to the ifunc resolver. */ #define _IFUNC_ARG_HWCAP (1ULL << 62) @@ -61,4 +63,33 @@ struct __ifunc_arg_t typedef struct __ifunc_arg_t __ifunc_arg_t; +/* Constants for IDs of HWCAP elements to be used with the + __ifunc_hwcap function below. */ +enum +{ + _IFUNC_ARG_AT_HWCAP = 1, + _IFUNC_ARG_AT_HWCAP2 = 2, + _IFUNC_ARG_AT_HWCAP3 = 3, + _IFUNC_ARG_AT_HWCAP4 = 4, +}; + +/* A helper function to obtain HWCAP element by its ID from the + parameters ARG0 and ARG1 passed to the ifunc resolver. Note that + ID 1 corresponds to AT_HWCAP, ID 2 corresponds to AT_HWCAP2, etc. + If there is no element available for the requested ID then 0 is + returned. If ID doesn't much any supported AT_HWCAP{,2,...} value, + then 0 is also returned. */ +static __inline unsigned long __attribute__ ((unused, always_inline)) +__ifunc_hwcap (unsigned long __id, + unsigned long __arg0, const unsigned long *__arg1) +{ + if (__glibc_likely (__arg0 & _IFUNC_ARG_HWCAP)) + { + const unsigned long size = __arg1[0]; + const unsigned long offset = __id * sizeof (unsigned long); + return offset < size && __id > 0 ? __arg1[__id] : 0; + } + return __id == 1 ? __arg0 : 0; +} + #endif diff --git a/sysdeps/aarch64/tst-ifunc-arg-1.c b/sysdeps/aarch64/tst-ifunc-arg-1.c index 9cc3d40c48..292c5ae9e3 100644 --- a/sysdeps/aarch64/tst-ifunc-arg-1.c +++ b/sysdeps/aarch64/tst-ifunc-arg-1.c @@ -60,6 +60,18 @@ do_test (void) TEST_COMPARE (saved_arg2._hwcap3, getauxval (AT_HWCAP3)); TEST_COMPARE (saved_arg2._hwcap4, getauxval (AT_HWCAP4)); + const unsigned long *saved_arg2_ptr = (const unsigned long *)&saved_arg2; + + TEST_COMPARE (__ifunc_hwcap (1, saved_arg1, saved_arg2_ptr), + getauxval (AT_HWCAP)); + TEST_COMPARE (__ifunc_hwcap (2, saved_arg1, saved_arg2_ptr), + getauxval (AT_HWCAP2)); + TEST_COMPARE (__ifunc_hwcap (3, saved_arg1, saved_arg2_ptr), + getauxval (AT_HWCAP3)); + TEST_COMPARE (__ifunc_hwcap (4, saved_arg1, saved_arg2_ptr), + getauxval (AT_HWCAP4)); + + return 0; } diff --git a/sysdeps/aarch64/tst-ifunc-arg-2.c b/sysdeps/aarch64/tst-ifunc-arg-2.c index d9950f0e37..c05129a132 100644 --- a/sysdeps/aarch64/tst-ifunc-arg-2.c +++ b/sysdeps/aarch64/tst-ifunc-arg-2.c @@ -63,6 +63,17 @@ do_test (void) TEST_COMPARE (saved_arg2._hwcap3, getauxval (AT_HWCAP3)); TEST_COMPARE (saved_arg2._hwcap4, getauxval (AT_HWCAP4)); + const unsigned long *saved_arg2_ptr = (const unsigned long *)&saved_arg2; + + TEST_COMPARE (__ifunc_hwcap (1, saved_arg1, saved_arg2_ptr), + getauxval (AT_HWCAP)); + TEST_COMPARE (__ifunc_hwcap (2, saved_arg1, saved_arg2_ptr), + getauxval (AT_HWCAP2)); + TEST_COMPARE (__ifunc_hwcap (3, saved_arg1, saved_arg2_ptr), + getauxval (AT_HWCAP3)); + TEST_COMPARE (__ifunc_hwcap (4, saved_arg1, saved_arg2_ptr), + getauxval (AT_HWCAP4)); + return 0; } diff --git a/sysdeps/aarch64/tst-ifunc-arg-3.c b/sysdeps/aarch64/tst-ifunc-arg-3.c new file mode 100644 index 0000000000..49d8866e8b --- /dev/null +++ b/sysdeps/aarch64/tst-ifunc-arg-3.c @@ -0,0 +1,97 @@ +/* Tests for __ifunc_hwcap helper function. + Copyright (C) 2025 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 + . */ + +#include +#include +#include + +#define CHECK_VALUES_WITH_ARG(p1, p2, p3, p4) \ + ({ \ + TEST_COMPARE (__ifunc_hwcap (0, _IFUNC_ARG_HWCAP, arg), 0); \ + TEST_COMPARE (__ifunc_hwcap (_IFUNC_ARG_AT_HWCAP, _IFUNC_ARG_HWCAP, arg), p1); \ + TEST_COMPARE (__ifunc_hwcap (_IFUNC_ARG_AT_HWCAP2, _IFUNC_ARG_HWCAP, arg), p2); \ + TEST_COMPARE (__ifunc_hwcap (_IFUNC_ARG_AT_HWCAP3, _IFUNC_ARG_HWCAP, arg), p3); \ + TEST_COMPARE (__ifunc_hwcap (_IFUNC_ARG_AT_HWCAP4, _IFUNC_ARG_HWCAP, arg), p4); \ + TEST_COMPARE (__ifunc_hwcap (5, _IFUNC_ARG_HWCAP, arg), 0); \ + }) + +#define CHECK_VALUES_WITHOUT_ARG(p1) \ + ({ \ + TEST_COMPARE (__ifunc_hwcap (0, p1, arg), 0); \ + TEST_COMPARE (__ifunc_hwcap (_IFUNC_ARG_AT_HWCAP, p1, arg), p1); \ + TEST_COMPARE (__ifunc_hwcap (_IFUNC_ARG_AT_HWCAP2, p1, arg), 0); \ + TEST_COMPARE (__ifunc_hwcap (_IFUNC_ARG_AT_HWCAP3, p1, arg), 0); \ + TEST_COMPARE (__ifunc_hwcap (_IFUNC_ARG_AT_HWCAP4, p1, arg), 0); \ + TEST_COMPARE (__ifunc_hwcap (5, p1, arg), 0); \ + }) + +static void +test_one (const unsigned long *arg) +{ + uint64_t size = arg[0] / sizeof (uint64_t); + + switch (size) + { + case 1: + CHECK_VALUES_WITH_ARG (0, 0, 0, 0); + CHECK_VALUES_WITHOUT_ARG (0); + break; + case 2: + CHECK_VALUES_WITH_ARG (1, 0, 0, 0); + CHECK_VALUES_WITHOUT_ARG (1); + break; + case 3: + CHECK_VALUES_WITH_ARG (1, 2, 0, 0); + CHECK_VALUES_WITHOUT_ARG (1); + break; + case 4: + CHECK_VALUES_WITH_ARG (1, 2, 3, 0); + CHECK_VALUES_WITHOUT_ARG (1); + break; + case 5: + CHECK_VALUES_WITH_ARG (1, 2, 3, 4); + CHECK_VALUES_WITHOUT_ARG (1); + break; + default: + TEST_VERIFY (0); // unexpected size + break; + } +} + +static int +do_test (void) +{ + uint64_t arg[_IFUNC_HWCAP_MAX + 1] = { + 0, /* Placeholder for size */ + _IFUNC_ARG_AT_HWCAP, /* AT_HWCAP */ + _IFUNC_ARG_AT_HWCAP2, /* AT_HWCAP2 */ + _IFUNC_ARG_AT_HWCAP3, /* AT_HWCAP3 */ + _IFUNC_ARG_AT_HWCAP4, /* AT_HWCAP4 */ + }; + + for (int k = 0; k <= _IFUNC_HWCAP_MAX; k++) + { + /* Update size */ + arg[0] = (k + 1) * sizeof (uint64_t); + test_one (arg); + } + + return 0; +} + +#include diff --git a/sysdeps/aarch64/tst-ifunc-arg-4.c b/sysdeps/aarch64/tst-ifunc-arg-4.c new file mode 100644 index 0000000000..c95ef9ebb3 --- /dev/null +++ b/sysdeps/aarch64/tst-ifunc-arg-4.c @@ -0,0 +1,67 @@ +/* Test for ifunc resolver that uses __ifunc_hwcap helper function. + Copyright (C) 2025 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 + . */ + +#include +#include +#include +#include +#include + +static int +one (void) +{ + return 1; +} + +static int +two (void) +{ + return 2; +} + +/* Resolver function. */ +static void * +resolver (uint64_t arg0, const uint64_t arg1[]) +{ + uint64_t hwcap2 = __ifunc_hwcap (_IFUNC_ARG_AT_HWCAP2, arg0, arg1); + if (hwcap2 & HWCAP2_POE) + return (void *)one; + else + return (void *)two; +} + +/* An extern visible ifunc symbol. */ +int fun (void) __attribute__((ifunc ("resolver"))); + +static int +do_test (void) +{ + if (getauxval (AT_HWCAP2) & HWCAP2_POE) + { + printf ("using 1st implementation\n"); + TEST_VERIFY (fun () == 1); + } + else + { + printf ("using 2nd implementation\n"); + TEST_VERIFY (fun () == 2); + } + return 0; +} + +#include