74 lines
2.6 KiB
C++
74 lines
2.6 KiB
C++
//===-- Implementation of tls for riscv -----------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/__support/OSUtil/syscall.h"
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#include "src/__support/threads/thread.h"
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#include "src/string/memory_utils/inline_memcpy.h"
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#include "startup/linux/do_start.h"
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#include <sys/mman.h>
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#include <sys/syscall.h>
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namespace LIBC_NAMESPACE {
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#ifdef SYS_mmap2
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static constexpr long MMAP_SYSCALL_NUMBER = SYS_mmap2;
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#elif SYS_mmap
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static constexpr long MMAP_SYSCALL_NUMBER = SYS_mmap;
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#else
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#error "mmap and mmap2 syscalls not available."
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#endif
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void init_tls(TLSDescriptor &tls_descriptor) {
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if (app.tls.size == 0) {
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tls_descriptor.size = 0;
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tls_descriptor.tp = 0;
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return;
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}
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// riscv64 follows the variant 1 TLS layout:
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const uintptr_t size_of_pointers = 2 * sizeof(uintptr_t);
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uintptr_t padding = 0;
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const uintptr_t ALIGNMENT_MASK = app.tls.align - 1;
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uintptr_t diff = size_of_pointers & ALIGNMENT_MASK;
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if (diff != 0)
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padding += (ALIGNMENT_MASK - diff) + 1;
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uintptr_t alloc_size = size_of_pointers + padding + app.tls.size;
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// We cannot call the mmap function here as the functions set errno on
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// failure. Since errno is implemented via a thread local variable, we cannot
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// use errno before TLS is setup.
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long mmap_ret_val = syscall_impl<long>(MMAP_SYSCALL_NUMBER, nullptr,
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alloc_size, PROT_READ | PROT_WRITE,
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MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
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// We cannot check the return value with MAP_FAILED as that is the return
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// of the mmap function and not the mmap syscall.
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if (mmap_ret_val < 0 && static_cast<uintptr_t>(mmap_ret_val) > -app.page_size)
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syscall_impl<long>(SYS_exit, 1);
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uintptr_t thread_ptr = uintptr_t(reinterpret_cast<uintptr_t *>(mmap_ret_val));
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uintptr_t tls_addr = thread_ptr + size_of_pointers + padding;
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inline_memcpy(reinterpret_cast<char *>(tls_addr),
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reinterpret_cast<const char *>(app.tls.address),
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app.tls.init_size);
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tls_descriptor.size = alloc_size;
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tls_descriptor.addr = thread_ptr;
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tls_descriptor.tp = tls_addr;
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}
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void cleanup_tls(uintptr_t addr, uintptr_t size) {
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if (size == 0)
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return;
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syscall_impl<long>(SYS_munmap, addr, size);
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}
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bool set_thread_ptr(uintptr_t val) {
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LIBC_INLINE_ASM("mv tp, %0\n\t" : : "r"(val));
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return true;
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}
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} // namespace LIBC_NAMESPACE
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