https://bugzilla.kernel.org/show_bug.cgi?id=70801 Michael Kerrisk <mtk.manpages@xxxxxxxxx> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |CODE_FIX --- Comment #3 from Michael Kerrisk <mtk.manpages@xxxxxxxxx> --- (In reply to Mike Frysinger from comment #1) > it depends entirely on the arch. a bunch do as the man page describes. the > generic ptrace layer is not used by a bunch. > > for example alpha/kernel/ptrace.c: > case PTRACE_PEEKTEXT: /* read word at location addr. */ > case PTRACE_PEEKDATA: > copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); > ret = -EIO; > if (copied != sizeof(tmp)) > break; > > force_successful_syscall_return(); > ret = tmp; > break; > > or ia64/kernel/ptrace.c: > case PTRACE_PEEKTEXT: > case PTRACE_PEEKDATA: > /* read word at location addr */ > if (access_process_vm(child, addr, &data, sizeof(data), 0) > != sizeof(data)) > return -EIO; > /* ensure return value is not mistaken for error code */ > force_successful_syscall_return(); > return data; > > it's the API that strace uses: > strace/util.c: > u.val = ptrace(PTRACE_PEEKDATA, pid, (char *) addr, 0); > > the generic glibc ignores it too: > glibc/misc/ptrace.c: > case PTRACE_PEEKDATA: > va_start(ap, request); > pid = va_arg(ap, pid_t); > addr = va_arg(ap, void *); > va_end(ap); > break; > > although apparently glibc's linux layer has been rewriting this silently: > if (request > 0 && request < 4) > data = &ret; > ... > if (res >= 0 && request > 0 && request < 4) > { > __set_errno (0); > return ret; > } > > where request {1,2,3} are PTRACE_PEEK{TEXT,DATA,USER} Thanks for the above, Mike. > as mentioned before, the man page is geared towards documenting the C > library interface rather than the syscall one. so the current docs are > correct. this could use noting in the NOTES section. Yes. I've noted that point in various informal contexts (such as mailing lists), and it's also hidden away here https://www.kernel.org/doc/man-pages/todo.html#migrate_to_kernel_source . But, like that info in the ptrace() page, it should be more obvious. I committed a patch, https://www.kernel.org/doc/man-pages/todo.html#migrate_to_kernel_source -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
