在 x86_64 程序集中处理信号 [重复]

Question

我想设置一个基本的信号陷阱。

global _start
%define stdout 1
%define sys_signal 48
%define SIGINT 2
%define SIGSEGV 11

section .text
exit:
    mov eax, 60
    mov rdi, 0
    syscall
catch:
    mov eax, 1
    mov rdi, stdout
    lea rsi, [message]
    mov rdx, 15
    syscall
    jmp exit

_start:
    ; jmp catch
    mov eax, sys_signal
    mov ebx, SIGINT
    mov ecx, catch
    int 80h
loop:
    jmp loop

section .data
    message: db "Signal caught!", 10

这会导致按下 Control-C 来中断程序而不是打印“信号被捕获！”的段错误。消息。

以上是this example的简化版。 （我也不知道要传递哪些选项来运行该示例。）

这是在 linux x86_64 上使用 nasm。但是我的系统似乎支持int 80h，但理想情况下我想用syscall 来做到这一点。

我的问题是：谁能给我一个在 x86_64 上使用 nasm 而不使用 C 的 SIGINT 或 SIGSEGV 信号处理的最小示例？

谢谢。

Answer 1

这是一个在 x86 assembler 代码中在 linux 上使用 sigaction 的示例，其抽象自：@987654321 @

  my $end   = Label;
  Jmp $end;                                                                     # Jump over subroutine definition
  my $start = SetLabel;
  Enter 0, 0;                                                                   # Inline code of signal handler
  Mov r15, rbp;                                                                 # Preserve the new stack frame
  Mov rbp, "[rbp]";                                                             # Restore our last stack frame
  PrintOutTraceBack;                                                            # Print our trace back
  Mov rbp, r15;                                                                 # Restore supplied stack frame
  Exit(0);                                                                      # Exit so we do not trampoline. Exit with code zero to show that the program is functioning correctly, else L<Assemble> will report an error.
  Leave;
  Ret;
  SetLabel $end;

  Mov r15, 0;                                                                   # Push sufficient zeros onto the stack to make a struct sigaction as described in: https://www.man7.org/linux/man-pages/man2/sigaction.2.html
  Push r15 for 1..16;

  Mov r15, $start;                                                              # Actual signal handler
  Mov "[rsp]", r15;                                                             # Show as signal handler
  Mov "[rsp+0x10]", r15;                                                        # Add as trampoline as well - which is fine because we exit in the handler so this will never be called
  Mov r15, 0x4000000;                                                           # Mask to show we have a trampoline which is, apparently, required on x86
  Mov "[rsp+0x8]", r15;                                                         # Confirm we have a trampoline

  Mov rax, 13;                                                                  # Sigaction from "kill -l"
  Mov rdi, 11;                                                                  # Confirmed SIGSEGV = 11 from kill -l and tracing with sde64
  Mov rsi, rsp;                                                                 # Sigaction structure on stack
  Mov rdx, 0;                                                                   # Confirmed by trace
  Mov r10, 8;                                                                   # Found by tracing "signal.c" with sde64 it is the width of the signal set and mask. "signal.c" is reproduced below.
  Syscall;
  Add rsp, 128;

  my $s = Subroutine                                                            # Subrotuine that will cause an error to occur to force a trace back to be printed
   {Mov r15, 0;
    Mov r15, "[r15]";                                                           # Try to read an unmapped memory location
   } [qw(in)], name => 'sub that causes a segv';                                # The name that will appear in the trace back

  $s->call(K(in, 42));

  ok Assemble(debug => 0, keep2 => 'signal', emulator=>0, eq => <<END);         # Cannot use the emulator because it does not understand signals

Subroutine trace back, depth: 0000 0000 0000 0001
0000 0000 0000 002A    sub that causes a segv

END

# /var/isde/sde64 -mix -ptr-check -debugtrace -- ./signal
##include <stdlib.h>
##include <stdio.h>
##include <signal.h>
##include <string.h>
##include <unistd.h>
#
#void handle_sigint(int sig)
# {exit(sig);
# }
#
#int main(void)
# {struct sigaction s;
#  memset(&s, 0, sizeof(s));
#  s.sa_sigaction = (void *)handle_sigint;
#
#  long a = 0xabcdef;
#  sigaction(SIGSEGV, &s, 0);
#  long *c = 0; *c = a;
# }
#
# gcc -finput-charset=UTF-8 -fmax-errors=7 -rdynamic -Wall -Wextra -Wno-unused-function -o signal signal.c  && /var/isde/sde64 -mix -ptr-check -debugtrace  -- ./signal; echo $?;