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newlib-cygwin/libgloss/riscv/crt0.S

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Add RISC-V port for libgloss Contributor list: - Andrew Waterman <andrew@sifive.com> - Palmer Dabbelt <palmer@dabbelt.com> - Kito Cheng <kito.cheng@gmail.com> - Alex Suykov <alex.suykov@gmail.com>
2017-07-27 16:45:47 +08:00
/* Copyright (c) 2017 SiFive Inc. All rights reserved.
This copyrighted material is made available to anyone wishing to use,
modify, copy, or redistribute it subject to the terms and conditions
Change license to FreeBSD License for RISC-V - For prevent confuse about what BSD license variant we used, 2- or 3-clause license, we change the license to FreeBSD license to make it unambiguously refers to the 2-clause license.
2017-08-21 10:30:30 +08:00
of the FreeBSD License. This program is distributed in the hope that
Add RISC-V port for libgloss Contributor list: - Andrew Waterman <andrew@sifive.com> - Palmer Dabbelt <palmer@dabbelt.com> - Kito Cheng <kito.cheng@gmail.com> - Alex Suykov <alex.suykov@gmail.com>
2017-07-27 16:45:47 +08:00
it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
including the implied warranties of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. A copy of this license is available at
http://www.opensource.org/licenses.
*/
RISC-V: Add _LITE_EXIT in crt0.S. This patch adds _LITE_EXIT in crt0.S to enable "lite exit" technique in RISC-V. The changes have been tested in riscv/riscv-gnu-toolchain by riscv-dejagnu with riscv-sim.exp/riscv-sim-nano.exp.
2019-05-23 08:41:25 +08:00
#include "newlib.h"
Add RISC-V port for libgloss Contributor list: - Andrew Waterman <andrew@sifive.com> - Palmer Dabbelt <palmer@dabbelt.com> - Kito Cheng <kito.cheng@gmail.com> - Alex Suykov <alex.suykov@gmail.com>
2017-07-27 16:45:47 +08:00
#=========================================================================
# crt0.S : Entry point for RISC-V user programs
#=========================================================================
.text
.global _start
.type _start, @function
_start:
# Initialize global pointer
.option push
.option norelax
1:auipc gp, %pcrel_hi(__global_pointer$)
addi gp, gp, %pcrel_lo(1b)
.option pop
RISC-V: Initialize the jvt CSR Set symbol '__jvt_base$' as weak. So if the symbol is not set in the linker script, the address would be 0. We initialize jvt CSR only if the address is not 0. Also use csr number directly instead of using symbolic name to prevent the backward incompatible issue. psabi reference: https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/2d770815dc9a8b11e61ea1abd487cb25ee56ad5e/riscv-elf.adoc#table-jump-relaxation
2024-01-05 15:06:39 +08:00
/* Initialize jvt CSR (reg addr: 0x0017) */
.weak __jvt_base$
lla a0, __jvt_base$
beqz a0, .Ljvt_init_end
.option push
.option norelax
.option arch, +zicsr
csrw 0x17, a0
.option pop
.Ljvt_init_end:
Add RISC-V port for libgloss Contributor list: - Andrew Waterman <andrew@sifive.com> - Palmer Dabbelt <palmer@dabbelt.com> - Kito Cheng <kito.cheng@gmail.com> - Alex Suykov <alex.suykov@gmail.com>
2017-07-27 16:45:47 +08:00
# Clear the bss segment
RISC-V: Use __bss_start for the starting point of .bss. It's more flexible for the positions of .bss and .data.
2021-02-04 15:34:00 +08:00
la a0, __bss_start
Add RISC-V port for libgloss Contributor list: - Andrew Waterman <andrew@sifive.com> - Palmer Dabbelt <palmer@dabbelt.com> - Kito Cheng <kito.cheng@gmail.com> - Alex Suykov <alex.suykov@gmail.com>
2017-07-27 16:45:47 +08:00
la a2, _end
sub a2, a2, a0
li a1, 0
call memset
RISC-V: Add _LITE_EXIT in crt0.S. This patch adds _LITE_EXIT in crt0.S to enable "lite exit" technique in RISC-V. The changes have been tested in riscv/riscv-gnu-toolchain by riscv-dejagnu with riscv-sim.exp/riscv-sim-nano.exp.
2019-05-23 08:41:25 +08:00
#ifdef _LITE_EXIT
# Make reference to atexit weak to avoid unconditionally pulling in
# support code. Refer to comments in __atexit.c for more details.
.weak atexit
la a0, atexit
beqz a0, .Lweak_atexit
.weak __libc_fini_array
#endif
Add RISC-V port for libgloss Contributor list: - Andrew Waterman <andrew@sifive.com> - Palmer Dabbelt <palmer@dabbelt.com> - Kito Cheng <kito.cheng@gmail.com> - Alex Suykov <alex.suykov@gmail.com>
2017-07-27 16:45:47 +08:00
la a0, __libc_fini_array # Register global termination functions
call atexit # to be called upon exit
RISC-V: Add _LITE_EXIT in crt0.S. This patch adds _LITE_EXIT in crt0.S to enable "lite exit" technique in RISC-V. The changes have been tested in riscv/riscv-gnu-toolchain by riscv-dejagnu with riscv-sim.exp/riscv-sim-nano.exp.
2019-05-23 08:41:25 +08:00
#ifdef _LITE_EXIT
.Lweak_atexit:
#endif
Add RISC-V port for libgloss Contributor list: - Andrew Waterman <andrew@sifive.com> - Palmer Dabbelt <palmer@dabbelt.com> - Kito Cheng <kito.cheng@gmail.com> - Alex Suykov <alex.suykov@gmail.com>
2017-07-27 16:45:47 +08:00
call __libc_init_array # Run global initialization functions
lw a0, 0(sp) # a0 = argc
addi a1, sp, __SIZEOF_POINTER__ # a1 = argv
li a2, 0 # a2 = envp = NULL
call main
tail exit
.size _start, .-_start