| 1 | /* The clone3 syscall wrapper. Linux/RISC-V version. |
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| 2 | Copyright (C) 2023-2024 Free Software Foundation, Inc. |
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| 3 | |
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| 4 | This file is part of the GNU C Library. |
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| 5 | |
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| 6 | The GNU C Library is free software; you can redistribute it and/or |
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| 7 | modify it under the terms of the GNU Lesser General Public |
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| 8 | License as published by the Free Software Foundation; either |
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| 9 | version 2.1 of the License, or (at your option) any later version. |
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| 10 | |
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| 11 | The GNU C Library is distributed in the hope that it will be useful, |
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 14 | Lesser General Public License for more details. |
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| 15 | |
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| 16 | You should have received a copy of the GNU Lesser General Public |
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| 17 | License along with the GNU C Library; if not, see |
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| 18 | <https://www.gnu.org/licenses/>. */ |
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| 19 | |
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| 20 | #include <asm/errno.h> |
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| 21 | #include <sys/asm.h> |
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| 22 | #include <sysdep.h> |
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| 23 | |
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| 24 | /* The userland implementation is: |
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| 25 | int clone3 (struct clone_args *cl_args, size_t size, |
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| 26 | int (*func)(void *arg), void *arg); |
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| 27 | |
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| 28 | the kernel entry is: |
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| 29 | int clone3 (struct clone_args *cl_args, size_t size); |
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| 30 | |
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| 31 | The parameters are passed in registers from userland: |
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| 32 | a0: cl_args |
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| 33 | a1: size |
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| 34 | a2: func |
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| 35 | a3: arg */ |
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| 36 | |
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| 37 | .text |
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| 38 | ENTRY(__clone3) |
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| 39 | /* Sanity check args. */ |
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| 40 | beqz a0, L(invalid) /* No NULL cl_args pointer. */ |
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| 41 | beqz a2, L(invalid) /* No NULL function pointer. */ |
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| 42 | |
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| 43 | /* Do the system call, the kernel expects: |
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| 44 | a7: system call number |
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| 45 | a0: cl_args |
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| 46 | a1: size */ |
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| 47 | li a7, __NR_clone3 |
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| 48 | scall |
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| 49 | |
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| 50 | bltz a0, L(error) |
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| 51 | beqz a0, L(thread_start) |
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| 52 | |
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| 53 | ret |
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| 54 | |
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| 55 | L(invalid): |
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| 56 | li a0, -EINVAL |
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| 57 | L(error): |
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| 58 | tail __syscall_error |
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| 59 | END (__clone3) |
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| 60 | |
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| 61 | ENTRY(__thread_start_clone3) |
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| 62 | L(thread_start): |
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| 63 | /* Terminate call stack by noting ra is undefined. Use a dummy |
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| 64 | .cfi_label to force starting the FDE. */ |
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| 65 | .cfi_label .Ldummy |
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| 66 | cfi_undefined (ra) |
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| 67 | |
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| 68 | /* Restore the arg for user's function and call the user's |
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| 69 | function. */ |
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| 70 | mv a0, a3 /* Argument pointer. */ |
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| 71 | jalr a2 |
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| 72 | |
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| 73 | /* Call exit with the function's return value. */ |
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| 74 | li a7, __NR_exit |
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| 75 | scall |
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| 76 | END(__thread_start_clone3) |
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| 77 | |
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| 78 | libc_hidden_def (__clone3) |
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| 79 | weak_alias (__clone3, clone3) |
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| 80 | |
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