https://bugzilla.kernel.org/show_bug.cgi?id=70801 Mike Frysinger <vapier@xxxxxxxxxx> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |vapier@xxxxxxxxxx --- Comment #1 from Mike Frysinger <vapier@xxxxxxxxxx> --- 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} 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. -- 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
