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Diffstat (limited to 'kernel/arch/x86_64/execsp.S')
| -rw-r--r-- | kernel/arch/x86_64/execsp.S | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/kernel/arch/x86_64/execsp.S b/kernel/arch/x86_64/execsp.S new file mode 100644 index 000000000000..d351dfb2d9e8 --- /dev/null +++ b/kernel/arch/x86_64/execsp.S @@ -0,0 +1,111 @@ +/* $NetBSD: execsp.S,v 1.2 2025/04/20 22:31:25 riastradh Exp $ */ + +/*- + * Copyright (c) 2025 The NetBSD Foundation, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED + * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS + * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#define _LOCORE + +#include <machine/asm.h> + +RCSID("$NetBSD: execsp.S,v 1.2 2025/04/20 22:31:25 riastradh Exp $") + +/* + * void execsp_start(void (*cleanup@rbx)(void), void *obj_main@rcx, + * struct ps_strings *ps_strings@rbx) + * + * ELF entry point. Saves the stack pointer in startsp and defers + * to the usual csu __start routine. + */ +ENTRY(execsp_start) + movq %rsp,_C_LABEL(startsp)(%rip) + /* + * No adjustment like in main because entry point is special + * and the amd64 csu __start routine takes care of it. + * + * XXX Why don't we just arrange to align it in the kernel + * anyway? + */ + jmp _C_LABEL(__start) +END(execsp_start) + +/* + * void execsp_ctor(void) + * + * ELF constructor. Saves the stack pointer in ctorsp and + * returns. + */ +ENTRY(execsp_ctor) + /* + * `The end of the input argument area shall be aligned on a + * [16-byte] boundary. In other words, the value of (%rsp + 8) + * is always a multiple of 16 when control is transferred to + * the function entry point.' + * + * To make it convenient for t_signal_and_sp.c, we subtract 8 + * from %rsp in order to get something congruent to zero modulo + * the stack alignemnt. + */ + movq %rsp,_C_LABEL(ctorsp)(%rip) + addq $-8,_C_LABEL(ctorsp)(%rip) + ret +END(execsp_ctor) + + /* Make execsp_ctor a constructor. */ + .section .ctors,"aw",@progbits + .p2align 3 + .quad _C_LABEL(execsp_ctor) + +/* + * int main(int argc@rdi, char **argv@rsi, ...) + * + * Main function. Saves the stack pointer in mainsp and returns + * zero. We will call execsp_main in execsp_dtor once dtorsp has + * been initialized. + */ +ENTRY(main) + movq %rsp,_C_LABEL(mainsp)(%rip) + addq $-8,_C_LABEL(mainsp)(%rip) + xorl %eax,%eax + ret +END(main) + +/* + * void execsp_dtor(void) + * + * ELF destructor. Saves the stack pointer in dtorsp and defers + * to the C execsp_main in h_execsp.c to report the stack pointers + * back to the t_signal_and_sp parent. + */ +ENTRY(execsp_dtor) + movq %rsp,_C_LABEL(dtorsp)(%rip) + addq $-8,_C_LABEL(dtorsp)(%rip) + jmp _C_LABEL(execsp_main) +END(execsp_dtor) + + /* Make execsp_ctor a destructor. */ + .section .dtors,"aw",@progbits + .p2align 3 + .quad _C_LABEL(execsp_dtor) |