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linux/arch/xtensa/kernel/signal.c

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// TODO coprocessor stuff
/*
* linux/arch/xtensa/kernel/signal.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
*
* Joe Taylor <joe@tensilica.com>
* Chris Zankel <chris@zankel.net>
*
*
*
*/
#include <xtensa/config/core.h>
#include <xtensa/hal.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#define DEBUG_SIG 0
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
asmlinkage long sys_wait4(pid_t pid,unsigned int * stat_addr, int options,
struct rusage * ru);
asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
extern struct task_struct *coproc_owners[];
/*
* Atomically swap in the new signal mask, and wait for a signal.
*/
int sys_sigsuspend(struct pt_regs *regs)
{
old_sigset_t mask = (old_sigset_t) regs->areg[3];
sigset_t saveset;
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->areg[2] = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(regs, &saveset))
return -EINTR;
}
}
asmlinkage int
sys_rt_sigsuspend(struct pt_regs *regs)
{
sigset_t *unewset = (sigset_t *) regs->areg[4];
size_t sigsetsize = (size_t) regs->areg[3];
sigset_t saveset, newset;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (copy_from_user(&newset, unewset, sizeof(newset)))
return -EFAULT;
sigdelsetmask(&newset, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
current->blocked = newset;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->areg[2] = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(regs, &saveset))
return -EINTR;
}
}
asmlinkage int
sys_sigaction(int sig, const struct old_sigaction *act,
struct old_sigaction *oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
if (act) {
old_sigset_t mask;
if (verify_area(VERIFY_READ, act, sizeof(*act)) ||
__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
__get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
return -EFAULT;
__get_user(new_ka.sa.sa_flags, &act->sa_flags);
__get_user(mask, &act->sa_mask);
siginitset(&new_ka.sa.sa_mask, mask);
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (verify_area(VERIFY_WRITE, oact, sizeof(*oact)) ||
__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
__put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
return -EFAULT;
__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
}
return ret;
}
asmlinkage int
sys_sigaltstack(struct pt_regs *regs)
{
const stack_t *uss = (stack_t *) regs->areg[4];
stack_t *uoss = (stack_t *) regs->areg[3];
if (regs->depc > 64)
panic ("Double exception sys_sigreturn\n");
return do_sigaltstack(uss, uoss, regs->areg[1]);
}
/*
* Do a signal return; undo the signal stack.
*/
struct sigframe
{
struct sigcontext sc;
struct _cpstate cpstate;
unsigned long extramask[_NSIG_WORDS-1];
unsigned char retcode[6];
unsigned int reserved[4]; /* Reserved area for chaining */
unsigned int window[4]; /* Window of 4 registers for initial context */
};
struct rt_sigframe
{
struct siginfo info;
struct ucontext uc;
struct _cpstate cpstate;
unsigned char retcode[6];
unsigned int reserved[4]; /* Reserved area for chaining */
unsigned int window[4]; /* Window of 4 registers for initial context */
};
extern void release_all_cp (struct task_struct *);
// FIXME restore_cpextra
static inline int
restore_cpextra (struct _cpstate *buf)
{
#if 0
/* The signal handler may have used coprocessors in which
* case they are still enabled. We disable them to force a
* reloading of the original task's CP state by the lazy
* context-switching mechanisms of CP exception handling.
* Also, we essentially discard any coprocessor state that the
* signal handler created. */
struct task_struct *tsk = current;
release_all_cp(tsk);
return __copy_from_user(tsk->thread.cpextra, buf, XTENSA_CP_EXTRA_SIZE);
#endif
return 0;
}
/* Note: We don't copy double exception 'tregs', we have to finish double exc. first before we return to signal handler! This dbl.exc.handler might cause another double exception, but I think we are fine as the situation is the same as if we had returned to the signal handerl and got an interrupt immediately...
*/
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
{
struct thread_struct *thread;
unsigned int err = 0;
unsigned long ps;
struct _cpstate *buf;
#define COPY(x) err |= __get_user(regs->x, &sc->sc_##x)
COPY(pc);
COPY(depc);
COPY(wmask);
COPY(lbeg);
COPY(lend);
COPY(lcount);
COPY(sar);
COPY(windowbase);
COPY(windowstart);
#undef COPY
/* For PS, restore only PS.CALLINC.
* Assume that all other bits are either the same as for the signal
* handler, or the user mode value doesn't matter (e.g. PS.OWB).
*/
err |= __get_user(ps, &sc->sc_ps);
regs->ps = (regs->ps & ~XCHAL_PS_CALLINC_MASK)
| (ps & XCHAL_PS_CALLINC_MASK);
/* Additional corruption checks */
if ((regs->windowbase >= (XCHAL_NUM_AREGS/4))
|| ((regs->windowstart & ~((1<<(XCHAL_NUM_AREGS/4)) - 1)) != 0) )
err = 1;
if ((regs->lcount > 0)
&& ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
err = 1;
/* Restore extended register state.
* See struct thread_struct in processor.h.
*/
thread = &current->thread;
err |= __copy_from_user (regs->areg, sc->sc_areg, XCHAL_NUM_AREGS*4);
err |= __get_user(buf, &sc->sc_cpstate);
if (buf) {
if (verify_area(VERIFY_READ, buf, sizeof(*buf)))
goto badframe;
err |= restore_cpextra(buf);
}
regs->syscall = -1; /* disable syscall checks */
return err;
badframe:
return 1;
}
static inline void
flush_my_cpstate(struct task_struct *tsk)
{
unsigned long flags;
local_irq_save(flags);
#if 0 // FIXME
for (i = 0; i < XCHAL_CP_NUM; i++) {
if (tsk == coproc_owners[i]) {
xthal_validate_cp(i);
xthal_save_cpregs(tsk->thread.cpregs_ptr[i], i);
/* Invalidate and "disown" the cp to allow
* callers the chance to reset cp state in the
* task_struct. */
xthal_invalidate_cp(i);
coproc_owners[i] = 0;
}
}
#endif
local_irq_restore(flags);
}
/* Return codes:
0: nothing saved
1: stuff to save, successful
-1: stuff to save, error happened
*/
static int
save_cpextra (struct _cpstate *buf)
{
#if (XCHAL_EXTRA_SA_SIZE == 0) && (XCHAL_CP_NUM == 0)
return 0;
#else
/* FIXME: If a task has never used a coprocessor, there is
* no need to save and restore anything. Tracking this
* information would allow us to optimize this section.
* Perhaps we can use current->used_math or (current->flags &
* PF_USEDFPU) or define a new field in the thread
* structure. */
/* We flush any live, task-owned cp state to the task_struct,
* then copy it all to the sigframe. Then we clear all
* cp/extra state in the task_struct, effectively
* clearing/resetting all cp/extra state for the signal
* handler (cp-exception handling will load these new values
* into the cp/extra registers.) This step is important for
* things like a floating-point cp, where the OS must reset
* the FCR to the default rounding mode. */
int err = 0;
struct task_struct *tsk = current;
flush_my_cpstate(tsk);
/* Note that we just copy everything: 'extra' and 'cp' state together.*/
err |= __copy_to_user(buf, tsk->thread.cp_save, XTENSA_CP_EXTRA_SIZE);
memset(tsk->thread.cp_save, 0, XTENSA_CP_EXTRA_SIZE);
#if (XTENSA_CP_EXTRA_SIZE == 0)
#error Sanity check on memset above, cpextra_size should not be zero.
#endif
return err ? -1 : 1;
#endif
}
static int
setup_sigcontext(struct sigcontext *sc, struct _cpstate *cpstate,
struct pt_regs *regs, unsigned long mask)
{
struct thread_struct *thread;
int err = 0;
//printk("setup_sigcontext\n");
#define COPY(x) err |= __put_user(regs->x, &sc->sc_##x)
COPY(pc);
COPY(ps);
COPY(depc);
COPY(wmask);
COPY(lbeg);
COPY(lend);
COPY(lcount);
COPY(sar);
COPY(windowbase);
COPY(windowstart);
#undef COPY
/* Save extended register state.
* See struct thread_struct in processor.h.
*/
thread = &current->thread;
err |= __copy_to_user (sc->sc_areg, regs->areg, XCHAL_NUM_AREGS * 4);
err |= save_cpextra(cpstate);
err |= __put_user(err ? NULL : cpstate, &sc->sc_cpstate);
/* non-iBCS2 extensions.. */
err |= __put_user(mask, &sc->oldmask);
return err;
}
asmlinkage int sys_sigreturn(struct pt_regs *regs)
{
struct sigframe *frame = (struct sigframe *)regs->areg[1];
sigset_t set;
if (regs->depc > 64)
panic ("Double exception sys_sigreturn\n");
if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
|| (_NSIG_WORDS > 1
&& __copy_from_user(&set.sig[1], &frame->extramask,
sizeof(frame->extramask))))
goto badframe;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(regs, &frame->sc))
goto badframe;
return regs->areg[2];
badframe:
force_sig(SIGSEGV, current);
return 0;
}
asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe *frame = (struct rt_sigframe *)regs->areg[1];
sigset_t set;
stack_t st;
int ret;
if (regs->depc > 64)
{
printk("!!!!!!! DEPC !!!!!!!\n");
return 0;
}
if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
goto badframe;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
goto badframe;
ret = regs->areg[2];
if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
goto badframe;
/* It is more difficult to avoid calling this function than to
call it and ignore errors. */
do_sigaltstack(&st, NULL, regs->areg[1]);
return ret;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* Set up a signal frame.
*/
/*
* Determine which stack to use..
*/
static inline void *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
sp = current->sas_ss_sp + current->sas_ss_size;
return (void *)((sp - frame_size) & -16ul);
}
#define USE_SIGRETURN 0
#define USE_RT_SIGRETURN 1
static int
gen_return_code(unsigned char *codemem, unsigned int use_rt_sigreturn)
{
unsigned int retcall;
int err = 0;
#if 0
/* Ignoring SA_RESTORER for now; it's supposed to be obsolete,
* and the xtensa glibc doesn't use it.
*/
if (ka->sa.sa_flags & SA_RESTORER) {
regs->pr = (unsigned long) ka->sa.sa_restorer;
} else
#endif /* 0 */
{
#if (__NR_sigreturn > 255) || (__NR_rt_sigreturn > 255)
/* The 12-bit immediate is really split up within the 24-bit MOVI
* instruction. As long as the above system call numbers fit within
* 8-bits, the following code works fine. See the Xtensa ISA for
* details.
*/
#error Generating the MOVI instruction below breaks!
#endif
retcall = use_rt_sigreturn ? __NR_rt_sigreturn : __NR_sigreturn;
#ifdef __XTENSA_EB__ /* Big Endian version */
/* Generate instruction: MOVI a2, retcall */
err |= __put_user(0x22, &codemem[0]);
err |= __put_user(0x0a, &codemem[1]);
err |= __put_user(retcall, &codemem[2]);
/* Generate instruction: SYSCALL */
err |= __put_user(0x00, &codemem[3]);
err |= __put_user(0x05, &codemem[4]);
err |= __put_user(0x00, &codemem[5]);
#elif defined __XTENSA_EL__ /* Little Endian version */
/* Generate instruction: MOVI a2, retcall */
err |= __put_user(0x22, &codemem[0]);
err |= __put_user(0xa0, &codemem[1]);
err |= __put_user(retcall, &codemem[2]);
/* Generate instruction: SYSCALL */
err |= __put_user(0x00, &codemem[3]);
err |= __put_user(0x50, &codemem[4]);
err |= __put_user(0x00, &codemem[5]);
#else
#error Must use compiler for Xtensa processors.
#endif
}
/* Flush generated code out of the data cache */
if (err == 0)
__flush_invalidate_cache_range((unsigned long)codemem, 6UL);
return err;
}
static void
set_thread_state(struct pt_regs *regs, void *stack, unsigned char *retaddr,
void *handler, unsigned long arg1, void *arg2, void *arg3)
{
/* Set up registers for signal handler */
start_thread(regs, (unsigned long) handler, (unsigned long) stack);
/* Set up a stack frame for a call4
* Note: PS.CALLINC is set to one by start_thread
*/
regs->areg[4] = (((unsigned long) retaddr) & 0x3fffffff) | 0x40000000;
regs->areg[6] = arg1;
regs->areg[7] = (unsigned long) arg2;
regs->areg[8] = (unsigned long) arg3;
}
static void setup_frame(int sig, struct k_sigaction *ka,
sigset_t *set, struct pt_regs *regs)
{
struct sigframe *frame;
int err = 0;
int signal;
frame = get_sigframe(ka, regs->areg[1], sizeof(*frame));
if (regs->depc > 64)
{
printk("!!!!!!! DEPC !!!!!!!\n");
return;
}
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
signal = current_thread_info()->exec_domain
&& current_thread_info()->exec_domain->signal_invmap
&& sig < 32
? current_thread_info()->exec_domain->signal_invmap[sig]
: sig;
err |= setup_sigcontext(&frame->sc, &frame->cpstate, regs, set->sig[0]);
if (_NSIG_WORDS > 1) {
err |= __copy_to_user(frame->extramask, &set->sig[1],
sizeof(frame->extramask));
}
/* Create sys_sigreturn syscall in stack frame */
err |= gen_return_code(frame->retcode, USE_SIGRETURN);
if (err)
goto give_sigsegv;
/* Create signal handler execution context.
* Return context not modified until this point.
*/
set_thread_state(regs, frame, frame->retcode,
ka->sa.sa_handler, signal, &frame->sc, NULL);
/* Set access mode to USER_DS. Nomenclature is outdated, but
* functionality is used in uaccess.h
*/
set_fs(USER_DS);
#if DEBUG_SIG
printk("SIG deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
current->comm, current->pid, signal, frame, regs->pc);
#endif
return;
give_sigsegv:
if (sig == SIGSEGV)
ka->sa.sa_handler = SIG_DFL;
force_sig(SIGSEGV, current);
}
static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe *frame;
int err = 0;
int signal;
frame = get_sigframe(ka, regs->areg[1], sizeof(*frame));
if (regs->depc > 64)
panic ("Double exception sys_sigreturn\n");
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
signal = current_thread_info()->exec_domain
&& current_thread_info()->exec_domain->signal_invmap
&& sig < 32
? current_thread_info()->exec_domain->signal_invmap[sig]
: sig;
err |= copy_siginfo_to_user(&frame->info, info);
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user((void *)current->sas_ss_sp,
&frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->areg[1]),
&frame->uc.uc_stack.ss_flags);
err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->cpstate,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
/* Create sys_rt_sigreturn syscall in stack frame */
err |= gen_return_code(frame->retcode, USE_RT_SIGRETURN);
if (err)
goto give_sigsegv;
/* Create signal handler execution context.
* Return context not modified until this point.
*/
set_thread_state(regs, frame, frame->retcode,
ka->sa.sa_handler, signal, &frame->info, &frame->uc);
/* Set access mode to USER_DS. Nomenclature is outdated, but
* functionality is used in uaccess.h
*/
set_fs(USER_DS);
#if DEBUG_SIG
printk("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08x\n",
current->comm, current->pid, signal, frame, regs->pc);
#endif
return;
give_sigsegv:
if (sig == SIGSEGV)
ka->sa.sa_handler = SIG_DFL;
force_sig(SIGSEGV, current);
}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*
* Note that we go through the signals twice: once to check the signals that
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*/
int do_signal(struct pt_regs *regs, sigset_t *oldset)
{
siginfo_t info;
int signr;
struct k_sigaction ka;
if (!oldset)
oldset = &current->blocked;
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
/* Are we from a system call? */
if (regs->syscall >= 0) {
/* If so, check system call restarting.. */
switch (regs->areg[2]) {
case ERESTARTNOHAND:
case ERESTART_RESTARTBLOCK:
regs->areg[2] = -EINTR;
break;
case ERESTARTSYS:
if (!(ka.sa.sa_flags & SA_RESTART)) {
regs->areg[2] = -EINTR;
break;
}
/* fallthrough */
case ERESTARTNOINTR:
regs->areg[2] = regs->syscall;
regs->pc -= 3;
}
}
if (signr == 0)
return 0; /* no signals delivered */
/* Whee! Actually deliver the signal. */
/* Set up the stack frame */
if (ka.sa.sa_flags & SA_SIGINFO)
setup_rt_frame(signr, &ka, &info, oldset, regs);
else
setup_frame(signr, &ka, oldset, regs);
if (ka.sa.sa_flags & SA_ONESHOT)
ka.sa.sa_handler = SIG_DFL;
spin_lock_irq(&current->sighand->siglock);
sigorsets(&current->blocked, &current->blocked, &ka.sa.sa_mask);
if (!(ka.sa.sa_flags & SA_NODEFER))
sigaddset(&current->blocked, signr);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
return 1;
}
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