1 | //===-- Implementation of tls for riscv -----------------------------------===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | |
9 | #include "src/__support/OSUtil/syscall.h" |
10 | #include "src/__support/macros/config.h" |
11 | #include "src/__support/threads/thread.h" |
12 | #include "src/string/memory_utils/inline_memcpy.h" |
13 | #include "startup/linux/do_start.h" |
14 | |
15 | #include <sys/mman.h> |
16 | #include <sys/syscall.h> |
17 | |
18 | namespace LIBC_NAMESPACE_DECL { |
19 | |
20 | #ifdef SYS_mmap2 |
21 | static constexpr long MMAP_SYSCALL_NUMBER = SYS_mmap2; |
22 | #elif SYS_mmap |
23 | static constexpr long MMAP_SYSCALL_NUMBER = SYS_mmap; |
24 | #else |
25 | #error "mmap and mmap2 syscalls not available." |
26 | #endif |
27 | |
28 | void init_tls(TLSDescriptor &tls_descriptor) { |
29 | if (app.tls.size == 0) { |
30 | tls_descriptor.size = 0; |
31 | tls_descriptor.tp = 0; |
32 | return; |
33 | } |
34 | |
35 | // riscv64 follows the variant 1 TLS layout: |
36 | const uintptr_t size_of_pointers = 2 * sizeof(uintptr_t); |
37 | uintptr_t padding = 0; |
38 | const uintptr_t ALIGNMENT_MASK = app.tls.align - 1; |
39 | uintptr_t diff = size_of_pointers & ALIGNMENT_MASK; |
40 | if (diff != 0) |
41 | padding += (ALIGNMENT_MASK - diff) + 1; |
42 | |
43 | uintptr_t alloc_size = size_of_pointers + padding + app.tls.size; |
44 | |
45 | // We cannot call the mmap function here as the functions set errno on |
46 | // failure. Since errno is implemented via a thread local variable, we cannot |
47 | // use errno before TLS is setup. |
48 | long mmap_ret_val = syscall_impl<long>(MMAP_SYSCALL_NUMBER, nullptr, |
49 | alloc_size, PROT_READ | PROT_WRITE, |
50 | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); |
51 | // We cannot check the return value with MAP_FAILED as that is the return |
52 | // of the mmap function and not the mmap syscall. |
53 | if (mmap_ret_val < 0 && static_cast<uintptr_t>(mmap_ret_val) > -app.page_size) |
54 | syscall_impl<long>(SYS_exit, 1); |
55 | uintptr_t thread_ptr = uintptr_t(reinterpret_cast<uintptr_t *>(mmap_ret_val)); |
56 | uintptr_t tls_addr = thread_ptr + size_of_pointers + padding; |
57 | inline_memcpy(reinterpret_cast<char *>(tls_addr), |
58 | reinterpret_cast<const char *>(app.tls.address), |
59 | app.tls.init_size); |
60 | tls_descriptor.size = alloc_size; |
61 | tls_descriptor.addr = thread_ptr; |
62 | tls_descriptor.tp = tls_addr; |
63 | } |
64 | |
65 | void cleanup_tls(uintptr_t addr, uintptr_t size) { |
66 | if (size == 0) |
67 | return; |
68 | syscall_impl<long>(SYS_munmap, addr, size); |
69 | } |
70 | |
71 | bool set_thread_ptr(uintptr_t val) { |
72 | LIBC_INLINE_ASM("mv tp, %0\n\t" : : "r" (val)); |
73 | return true; |
74 | } |
75 | } // namespace LIBC_NAMESPACE_DECL |
76 | |