void handle_syscall(struct uml_pt_regs *r)
{
struct pt_regs *regs = container_of(r, struct pt_regs, regs);
int syscall;
/* Initialize the syscall number and default return value. */
UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);
if (syscall_trace_enter(regs))
return;
/* Do the seccomp check after ptrace; failures should be fast. */
if (secure_computing(NULL) == -1)
return;
/* Update the syscall number after orig_ax has potentially been updated
* with ptrace.
*/
UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
syscall = UPT_SYSCALL_NR(r);
if (syscall >= 0 && syscall <= __NR_syscall_max)
PT_REGS_SET_SYSCALL_RETURN(regs,
EXECUTE_SYSCALL(syscall, regs));
syscall_trace_leave(regs);
}
/*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
{
int err, status;
/* Mark this as a syscall */
UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
if (!local_using_sysemu)
{
err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
if(err < 0)
panic("handle_trap - nullifying syscall failed errno = %d\n",
errno);
err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
if(err < 0)
panic("handle_trap - continuing to end of syscall failed, "
"errno = %d\n", errno);
CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
if((err < 0) || !WIFSTOPPED(status) ||
(WSTOPSIG(status) != SIGTRAP + 0x80))
panic("handle_trap - failed to wait at end of syscall, "
"errno = %d, status = %d\n", errno, status);
}
handle_syscall(regs);
}
static void handle_trap(int pid, union uml_pt_regs *regs)
{
int err, syscall_nr, status;
syscall_nr = PT_SYSCALL_NR(regs->skas.regs);
UPT_SYSCALL_NR(regs) = syscall_nr;
if(syscall_nr < 1){
relay_signal(SIGTRAP, regs);
return;
}
err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
if(err < 0)
panic("handle_trap - nullifying syscall failed errno = %d\n",
errno);
err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
if(err < 0)
panic("handle_trap - continuing to end of syscall failed, "
"errno = %d\n", errno);
CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
if((err < 0) || !WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
panic("handle_trap - failed to wait at end of syscall, "
"errno = %d, status = %d\n", errno, status);
handle_syscall(regs);
}
void userspace(union uml_pt_regs *regs)
{
int err, status, op, pid = userspace_pid[0];
int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
while(1){
restore_registers(pid, regs);
/* Now we set local_using_sysemu to be used for one loop */
local_using_sysemu = get_using_sysemu();
op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
err = ptrace(op, pid, 0, 0);
if(err)
panic("userspace - could not resume userspace process, "
"pid=%d, ptrace operation = %d, errno = %d\n",
op, errno);
CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
if(err < 0)
panic("userspace - waitpid failed, errno = %d\n",
errno);
regs->skas.is_user = 1;
save_registers(pid, regs);
UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
if(WIFSTOPPED(status)){
switch(WSTOPSIG(status)){
case SIGSEGV:
handle_segv(pid, regs);
break;
case SIGTRAP + 0x80:
handle_trap(pid, regs, local_using_sysemu);
break;
case SIGTRAP:
relay_signal(SIGTRAP, regs);
break;
case SIGIO:
case SIGVTALRM:
case SIGILL:
case SIGBUS:
case SIGFPE:
case SIGWINCH:
user_signal(WSTOPSIG(status), regs, pid);
break;
default:
printk("userspace - child stopped with signal "
"%d\n", WSTOPSIG(status));
}
interrupt_end();
/* Avoid -ERESTARTSYS handling in host */
PT_SYSCALL_NR(regs->skas.regs) = -1;
}
}
}
static void __init check_sysemu(void)
{
unsigned long regs[MAX_REG_NR];
int pid, n, status, count=0;
non_fatal("Checking syscall emulation patch for ptrace...");
sysemu_supported = 0;
pid = start_ptraced_child();
if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
goto fail;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
fatal_perror("check_sysemu : wait failed");
if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
fatal("check_sysemu : expected SIGTRAP, got status = %d\n",
status);
if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
fatal_perror("check_sysemu : PTRACE_GETREGS failed");
if (PT_SYSCALL_NR(regs) != __NR_getpid) {
non_fatal("check_sysemu got system call number %d, "
"expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
goto fail;
}
n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
if (n < 0) {
non_fatal("check_sysemu : failed to modify system call "
"return");
goto fail;
}
if (stop_ptraced_child(pid, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 1;
non_fatal("OK\n");
set_using_sysemu(!force_sysemu_disabled);
non_fatal("Checking advanced syscall emulation patch for ptrace...");
pid = start_ptraced_child();
if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
(void *) PTRACE_O_TRACESYSGOOD) < 0))
fatal_perror("check_sysemu: PTRACE_OLDSETOPTIONS failed");
while (1) {
count++;
if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
goto fail;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if (n < 0)
fatal_perror("check_sysemu: wait failed");
if (WIFSTOPPED(status) &&
(WSTOPSIG(status) == (SIGTRAP|0x80))) {
if (!count) {
non_fatal("check_sysemu: SYSEMU_SINGLESTEP "
"doesn't singlestep");
goto fail;
}
n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
os_getpid());
if (n < 0)
fatal_perror("check_sysemu : failed to modify "
"system call return");
break;
}
else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
count++;
else {
non_fatal("check_sysemu: expected SIGTRAP or "
"(SIGTRAP | 0x80), got status = %d\n",
status);
goto fail;
}
}
if (stop_ptraced_child(pid, 0, 0) < 0)
goto fail_stopped;
sysemu_supported = 2;
non_fatal("OK\n");
if (!force_sysemu_disabled)
set_using_sysemu(sysemu_supported);
return;
fail:
stop_ptraced_child(pid, 1, 0);
fail_stopped:
non_fatal("missing\n");
}