620a72252e
Talking futher to the person doing the glibc risc-v ifunc work, they clarified that glibc _is_ passing hwcap as the first argument, and the null pointer is actually the second argument. https://sourceware.org/pipermail/libc-alpha/2023-August/150967.html So since our whole purpose here was source compatibility, let's do what they're actually doing, and let's add some tests. I've also added a test that __riscv_hwprobe() works from an ifunc resolver because that's one place where it might well be used. That said, one other thing that came out of the discussion is that I actually went away and looked at a sample of top apps to see how many are using ifuncs currently. The result? Zero. So although this _might_ be interesting long term (especially if clang gets riscv64 FMV), I think we've done more than we need to with riscv64 ifuncs for now! Test: ran locally, both dynamic and static tests Change-Id: Ie2044d9f4e47c32c00ad381f045c537f4df38b08
113 lines
2.6 KiB
C++
113 lines
2.6 KiB
C++
/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <gtest/gtest.h>
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#include <sys/auxv.h>
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#if defined(__BIONIC__)
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#include <sys/ifunc.h>
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#endif
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typedef int (*fn_ptr_t)();
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int ret42() {
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return 42;
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}
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extern "C" fn_ptr_t resolver() {
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return ret42;
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}
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int ifunc() __attribute__((ifunc("resolver")));
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TEST(ifunc, function) {
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ASSERT_EQ(42, ifunc());
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}
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#if defined(__BIONIC__)
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#if defined(__aarch64__)
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static uint64_t g_hwcap;
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static __ifunc_arg_t g_arg;
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extern "C" fn_ptr_t hwcap_resolver(uint64_t hwcap, __ifunc_arg_t* arg)
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__attribute__((no_sanitize("hwaddress"))) {
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g_hwcap = hwcap;
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g_arg = *arg;
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return ret42;
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}
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#elif defined(__arm__)
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static unsigned long g_hwcap;
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extern "C" fn_ptr_t hwcap_resolver(unsigned long hwcap) {
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g_hwcap = hwcap;
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return ret42;
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}
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#elif defined(__riscv)
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#include <sys/hwprobe.h>
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static uint64_t g_hwcap;
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static riscv_hwprobe g_hwprobes[] = {{.key = RISCV_HWPROBE_KEY_IMA_EXT_0}};
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extern "C" fn_ptr_t hwcap_resolver(uint64_t hwcap, void* null) {
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// Check hwcap like arm32/arm64.
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g_hwcap = hwcap;
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// For now, the pointer argument is reserved for future expansion.
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if (null != NULL) abort();
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// Ensure that __riscv_hwprobe() can be called from an ifunc.
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if (__riscv_hwprobe(g_hwprobes, 1, 0, nullptr, 0) != 0) return nullptr;
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return ret42;
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}
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#else
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extern "C" fn_ptr_t hwcap_resolver() {
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return ret42;
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}
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#endif
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int hwcap() __attribute__((ifunc("hwcap_resolver")));
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TEST(ifunc, hwcap) {
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ASSERT_EQ(42, hwcap());
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#if defined(__aarch64__)
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EXPECT_EQ(getauxval(AT_HWCAP) | _IFUNC_ARG_HWCAP, g_hwcap);
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EXPECT_EQ(sizeof(__ifunc_arg_t), g_arg._size);
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EXPECT_EQ(getauxval(AT_HWCAP), g_arg._hwcap);
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EXPECT_EQ(getauxval(AT_HWCAP2), g_arg._hwcap2);
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#elif defined(__arm__)
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EXPECT_EQ(getauxval(AT_HWCAP), g_hwcap);
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#elif defined(__riscv)
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EXPECT_EQ(getauxval(AT_HWCAP), g_hwcap);
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riscv_hwprobe probes[] = {{.key = RISCV_HWPROBE_KEY_IMA_EXT_0}};
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ASSERT_EQ(0, __riscv_hwprobe(probes, 1, 0, nullptr, 0));
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EXPECT_EQ(probes[0].value, g_hwprobes[0].value);
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#endif
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}
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#endif // defined(__BIONIC__)
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