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SIGSEGV: handle and pretty-print on amd64-linux

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This commit is contained in:
Markus F.X.J. Oberhumer 2025-08-10 09:39:29 +02:00
parent 1f0036a460
commit 4e88556c94
1 changed files with 16 additions and 21 deletions
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37
src/stub/src/amd64-linux.elf-entry.S
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@ -351,7 +351,7 @@ sigsegv_sigaction:
mov $end_announce_sigaction - announce_sigaction,%edx // arg3 len
lea announce_sigaction(%rip),%rsi // arg2 buf
push $2; pop %rdi // arg1 fd_stderr
push $__NR_write; pop %eax; syscall // ignore error on write()
push $__NR_write; pop %rax; syscall // ignore error on write()
xor %esi,%esi // arg2 O_RDONLY
lea proc_self_maps(%rip),%arg1
@ -396,25 +396,17 @@ minus_q:
path_gdb:
.asciz "/usr/bin/gdb"
commands_gdb:
.ascii "set prompt\n" // null string prompt
.ascii "info inferiors\n"
// ucontext_t, mcontext_t, gregset_t, gret_t, REG_xxx: <sys/ucontext.h>
// stack_t <bits/types/stack_t.h>
.ascii "print \"r8 - r15\"\n"
.ascii "x/8xg $rdx + 5*8\n"
.ascii "print \"r8, r9\"\n"
.ascii "x/2xg $rdx + 5*8\n"
.ascii "print \"r10, r11\"\n"
.ascii "x/2xg\n"
.ascii "print \"r12, r13\"\n"
.ascii "x/2xg\n"
.ascii "print \"r14, r15\"\n"
.ascii "x/2xg\n"
.ascii "print \"rdi, rsi\"\n"
.ascii "x/2xg\n"
.ascii "print \"rbp, rbx\"\n"
.ascii "x/2xg\n"
.ascii "print \"rdx, rax\"\n"
.ascii "x/2xg\n"
.ascii "print \"rcx, rsp\"\n"
.ascii "x/2xg\n"
.ascii "print \"rdi, rsi, rbp, rbx\"\n"
.ascii "x/4xg\n"
.ascii "print \"rdx, rax, rcx, rsp\"\n"
.ascii "x/4xg\n"
.ascii "print \"rip, efl\"\n"
.ascii "x/2xg\n"
@ -422,7 +414,10 @@ commands_gdb:
.ascii "print \"faulting instr\"\n"
.ascii "x/i $pc\n"
.ascii "print \"fault context\"\n"
.ascii "x/24i $pc - 0x20\n"
.ascii "x/16i $pc - 0x20\n"
.ascii "print \"user stack\"\n"
.ascii "x/64xg *(long *)($rdx + 5*8 + 15*8)\n"
.ascii "kill\n"
.ascii "quit 1"
@ -441,10 +436,10 @@ O_RDONLY= 0
push $PATH_MAX; pop %arg3
__NR_read= 0
push $__NR_read; pop %rax; call sys_check
push $__NR_close; pop %eax; call sys_check
push $__NR_close; pop %rax; call sys_check
__NR_getppid= 110
push $__NR_getppid; pop %eax; syscall
push $__NR_getppid; pop %rax; syscall
push %rax; pop %rsi
xor %eax,%eax; push %rax; push %rax // decimal(pid) fits in 16 bytes
push %rsp; pop %rdi; call unsimal