diff options
Diffstat (limited to 'exec/loader-x86_64.s')
| -rw-r--r-- | exec/loader-x86_64.s | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/exec/loader-x86_64.s b/exec/loader-x86_64.s new file mode 100644 index 00000000000..07227d38396 --- /dev/null +++ b/exec/loader-x86_64.s @@ -0,0 +1,180 @@ +define(`CC', ` +dnl') + +CC Copyright (C) 2023 Free Software Foundation, Inc. +CC +CC This file is part of GNU Emacs. +CC +CC GNU Emacs is free software: you can redistribute it and/or modify +CC it under the terms of the GNU General Public License as published +CC by the Free Software Foundation, either version 3 of the License, +CC or (at your option) any later version. +CC +CC GNU Emacs is distributed in the hope that it will be useful, but +CC WITHOUT ANY WARRANTY; without even the implied warranty of +CC MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +CC General Public License for more details. +CC +CC You should have received a copy of the GNU General Public License +CC along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. + + .section .text + .global _start +_start: + #movq $35, %rax CC SYS_nanosleep + #leaq timespec(%rip), %rdi + #xorq %rsi, %rsi + #syscall + popq %r13 CC original SP + popq %r15 CC size of load area. + movq $-1, %r12 CC r12 is the interpreter fd +.next_action: + movq (%rsp), %r14 CC action number + movq %r14, %r15 CC original action number + andq $-17, %r14 + cmpq $0, %r14 CC open file? + je .open_file + cmpq $3, %r14 CC jump? + je .rest_of_exec + cmpq $4, %r14 CC anonymous mmap? + je .do_mmap_anon +.do_mmap: + movq $9, %rax CC SYS_mmap + movq 8(%rsp), %rdi CC address + movq 16(%rsp), %r9 CC offset + movq 24(%rsp), %rdx CC protection + movq 32(%rsp), %rsi CC length + movq 40(%rsp), %r10 CC flags + CC set r8 to the primary fd unless r15 & 16 + testq $16, %r15 + movq %r12, %r8 + cmovzq %rbx, %r8 +.do_mmap_1: + syscall + cmpq $-1, %rax CC mmap failed + je .perror + movq 48(%rsp), %r9 CC clear + testq %r9, %r9 + jz .continue + movq 8(%rsp), %r10 CC start of mapping + addq 32(%rsp), %r10 CC end of mapping + subq %r9, %r10 CC start of clear area +.again: + testq %r9, %r9 + jz .continue + subq $1, %r9 + movb $0, (%r10, %r9, 1) + jmp .again +.continue: + leaq 56(%rsp), %rsp + jmp .next_action +.do_mmap_anon: + movq $9, %rax CC SYS_mmap + movq 8(%rsp), %rdi CC address + movq 16(%rsp), %r9 CC offset + movq 24(%rsp), %rdx CC protection + movq 32(%rsp), %rsi CC length + movq 40(%rsp), %r10 CC flags + movq $-1, %r8 CC -1 + jmp .do_mmap_1 +.open_file: + movq $2, %rax CC SYS_open + leaq 8(%rsp), %rdi CC rdi = %rsp + 8 + xorq %rsi, %rsi CC flags = O_RDONLY + xorq %rdx, %rdx CC mode = 0 + syscall + cmpq $-1, %rax CC open failed + jle .perror + movq %rdi, %rsp CC rsp = start of string + subq $1, %rsp +.nextc: + addq $1, %rsp + cmpb $0, (%rsp) CC *rsp == 0? + jne .nextc + addq $8, %rsp CC adjust past rsp prior to rounding + andq $-8, %rsp CC round rsp up to the next quad + testq $16, %r15 CC r15 & 16? + jz .primary + movq %rax, %r12 CC otherwise, move fd to r12 + jmp .next_action +.primary: + movq %rax, %rbx CC if not, move fd to rbx + jmp .next_action +.perror: + movq %rax, %r12 CC error code + negq %r12 + movq $1, %rax CC SYS_write + movq $1, %rdi CC stdout + leaq error(%rip), %rsi CC buffer + movq $23, %rdx CC count + syscall + movq $60, %rax CC SYS_exit + movq %r12, %rdi CC code + syscall +.rest_of_exec: CC rsp now points to six quads: + movq %rsp, %r8 CC now, they are r8 + movq %r13, %rsp CC restore SP + popq %r10 CC argc + leaq 8(%rsp,%r10,8), %rsp CC now at start of environ +.skip_environ: + popq %r10 CC envp[N] + testq %r10, %r10 CC envp[n]? + jnz .skip_environ CC otherwise, rsp is now at the start of auxv +.one_auxv: + popq %rcx CC auxv type + addq $8, %rsp CC skip value + testq %rcx, %rcx CC is 0? + jz .cleanup + cmpq $3, %rcx CC is AT_PHDR? + je .replace_phdr + cmpq $4, %rcx CC is AT_PHENT? + je .replace_phent + cmpq $5, %rcx CC is AT_PHNUM? + je .replace_phnum + cmpq $9, %rcx CC is AT_ENTRY? + je .replace_entry + cmpq $7, %rcx CC is AT_BASE? + je .replace_base + jmp .one_auxv +.replace_phdr: + movq 40(%r8), %r9 + movq %r9, -8(%rsp) CC set at_phdr + jmp .one_auxv +.replace_phent: + movq 24(%r8), %r9 + movq %r9, -8(%rsp) CC set at_phent + jmp .one_auxv +.replace_phnum: + movq 32(%r8), %r9 + movq %r9, -8(%rsp) CC set at_phnum + jmp .one_auxv +.replace_entry: + movq 16(%r8), %r9 + movq %r9, -8(%rsp) CC set at_entry + jmp .one_auxv +.replace_base: + movq 48(%r8), %r9 + movq %r9, -8(%rsp) CC set at_base + jmp .one_auxv +.cleanup: + movq $3, %rax CC SYS_close + cmpq $-1, %r12 CC see if interpreter fd is set + jne .cleanup_1 + movq %r12, %rdi + syscall +.cleanup_1: + movq $3, %rax CC SYS_close + movq %rbx, %rdi + syscall +.enter: + pushq $0 + popfq CC clear FP state + movq %r13, %rsp CC restore SP + xorq %rdx, %rdx CC clear rtld_fini + jmpq *8(%r8) CC entry + +error: + .ascii "_start: internal error." +timespec: + .quad 10 + .quad 10 |