| 1 | /* Startup code compliant to the ELF RISC-V ABI. |
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| 2 | Copyright (C) 1995-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | In addition to the permissions in the GNU Lesser General Public |
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| 11 | License, the Free Software Foundation gives you unlimited |
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| 12 | permission to link the compiled version of this file with other |
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| 13 | programs, and to distribute those programs without any restriction |
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| 14 | coming from the use of this file. (The GNU Lesser General Public |
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| 15 | License restrictions do apply in other respects; for example, they |
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| 16 | cover modification of the file, and distribution when not linked |
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| 17 | into another program.) |
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| 18 | |
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| 19 | Note that people who make modified versions of this file are not |
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| 20 | obligated to grant this special exception for their modified |
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| 21 | versions; it is their choice whether to do so. The GNU Lesser |
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| 22 | General Public License gives permission to release a modified |
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| 23 | version without this exception; this exception also makes it |
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| 24 | possible to release a modified version which carries forward this |
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| 25 | exception. |
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| 26 | |
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| 27 | The GNU C Library is distributed in the hope that it will be useful, |
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| 28 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 29 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 30 | Lesser General Public License for more details. |
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| 31 | |
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| 32 | You should have received a copy of the GNU Lesser General Public |
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| 33 | License along with the GNU C Library. If not, see |
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| 34 | <https://www.gnu.org/licenses/>. */ |
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| 35 | |
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| 36 | #define __ASSEMBLY__ 1 |
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| 37 | #include <entry.h> |
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| 38 | #include <sysdep.h> |
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| 39 | #include <sys/asm.h> |
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| 40 | |
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| 41 | /* The entry point's job is to call __libc_start_main. Per the ABI, |
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| 42 | a0 contains the address of a function to be passed to atexit. |
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| 43 | __libc_start_main wants this in a5. */ |
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| 44 | |
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| 45 | ENTRY (ENTRY_POINT) |
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| 46 | /* Terminate call stack by noting ra is undefined. Use a dummy |
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| 47 | .cfi_label to force starting the FDE. */ |
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| 48 | .cfi_label .Ldummy |
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| 49 | cfi_undefined (ra) |
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| 50 | call load_gp |
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| 51 | mv a5, a0 /* rtld_fini. */ |
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| 52 | /* main may be in a shared library. */ |
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| 53 | la a0, main |
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| 54 | REG_L a1, 0(sp) /* argc. */ |
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| 55 | addi a2, sp, SZREG /* argv. */ |
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| 56 | andi sp, sp, ALMASK /* Align stack. */ |
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| 57 | li a3, 0 /* Used to be init. */ |
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| 58 | li a4, 0 /* Used to be fini. */ |
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| 59 | mv a6, sp /* stack_end. */ |
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| 60 | |
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| 61 | call __libc_start_main@plt |
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| 62 | ebreak |
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| 63 | END (ENTRY_POINT) |
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| 64 | |
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| 65 | /* Dynamic links need the global pointer to be initialized prior to calling |
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| 66 | any shared library's initializers, so we use preinit_array to load it. |
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| 67 | This doesn't cut it for static links, though, since the global pointer |
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| 68 | needs to be initialized before calling __libc_start_main in that case. |
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| 69 | So we redundantly initialize it at the beginning of _start. */ |
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| 70 | |
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| 71 | load_gp: |
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| 72 | .option push |
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| 73 | .option norelax |
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| 74 | lla gp, __global_pointer$ |
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| 75 | .option pop |
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| 76 | ret |
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| 77 | |
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| 78 | .section .preinit_array,"aw" |
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| 79 | .dc.a load_gp |
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| 80 | |
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| 81 | /* Define a symbol for the first piece of initialized data. */ |
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| 82 | .data |
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| 83 | .globl __data_start |
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| 84 | __data_start: |
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| 85 | .weak data_start |
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| 86 | data_start = __data_start |
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| 87 | |
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