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2dd12baa04
Mark the ra register as undefined in _start, so that unwinding through main works correctly. Also, don't use a tail call so that ra points after the call to __libc_start_main, not after the previous call.
87 lines
3.1 KiB
ArmAsm
87 lines
3.1 KiB
ArmAsm
/* Startup code compliant to the ELF RISC-V ABI.
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Copyright (C) 1995-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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In addition to the permissions in the GNU Lesser General Public
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License, the Free Software Foundation gives you unlimited
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permission to link the compiled version of this file with other
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programs, and to distribute those programs without any restriction
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coming from the use of this file. (The GNU Lesser General Public
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License restrictions do apply in other respects; for example, they
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cover modification of the file, and distribution when not linked
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into another program.)
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Note that people who make modified versions of this file are not
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obligated to grant this special exception for their modified
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versions; it is their choice whether to do so. The GNU Lesser
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General Public License gives permission to release a modified
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version without this exception; this exception also makes it
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possible to release a modified version which carries forward this
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exception.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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#define __ASSEMBLY__ 1
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#include <entry.h>
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#include <sysdep.h>
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#include <sys/asm.h>
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/* The entry point's job is to call __libc_start_main. Per the ABI,
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a0 contains the address of a function to be passed to atexit.
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__libc_start_main wants this in a5. */
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ENTRY (ENTRY_POINT)
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/* Terminate call stack by noting ra is undefined. Use a dummy
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.cfi_label to force starting the FDE. */
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.cfi_label .Ldummy
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cfi_undefined (ra)
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call .Lload_gp
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mv a5, a0 /* rtld_fini. */
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/* main may be in a shared library. */
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la a0, main
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REG_L a1, 0(sp) /* argc. */
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addi a2, sp, SZREG /* argv. */
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andi sp, sp, ALMASK /* Align stack. */
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lla a3, __libc_csu_init
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lla a4, __libc_csu_fini
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mv a6, sp /* stack_end. */
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call __libc_start_main@plt
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ebreak
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END (ENTRY_POINT)
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/* Dynamic links need the global pointer to be initialized prior to calling
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any shared library's initializers, so we use preinit_array to load it.
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This doesn't cut it for static links, though, since the global pointer
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needs to be initialized before calling __libc_start_main in that case.
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So we redundantly initialize it at the beginning of _start. */
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.Lload_gp:
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.option push
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.option norelax
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lla gp, __global_pointer$
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.option pop
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ret
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.section .preinit_array,"aw"
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.dc.a .Lload_gp
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/* Define a symbol for the first piece of initialized data. */
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.data
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.globl __data_start
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__data_start:
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.weak data_start
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data_start = __data_start
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