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-rw-r--r--arch/xtensa/kernel/signal.c533
1 files changed, 533 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c
new file mode 100644
index 000000000..5c01d7e70
--- /dev/null
+++ b/arch/xtensa/kernel/signal.c
@@ -0,0 +1,533 @@
+/*
+ * arch/xtensa/kernel/signal.c
+ *
+ * Default platform functions.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2005, 2006 Tensilica Inc.
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
+ *
+ * Chris Zankel <chris@zankel.net>
+ * Joe Taylor <joe@tensilica.com>
+ */
+
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/ptrace.h>
+#include <linux/personality.h>
+#include <linux/resume_user_mode.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/ucontext.h>
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+#include <asm/coprocessor.h>
+#include <asm/unistd.h>
+
+extern struct task_struct *coproc_owners[];
+
+struct rt_sigframe
+{
+ struct siginfo info;
+ struct ucontext uc;
+ struct {
+ xtregs_opt_t opt;
+ xtregs_user_t user;
+#if XTENSA_HAVE_COPROCESSORS
+ xtregs_coprocessor_t cp;
+#endif
+ } xtregs;
+ unsigned char retcode[6];
+ unsigned int window[4];
+};
+
+#if defined(USER_SUPPORT_WINDOWED)
+/*
+ * Flush register windows stored in pt_regs to stack.
+ * Returns 1 for errors.
+ */
+
+static int
+flush_window_regs_user(struct pt_regs *regs)
+{
+ const unsigned long ws = regs->windowstart;
+ const unsigned long wb = regs->windowbase;
+ unsigned long sp = 0;
+ unsigned long wm;
+ int err = 1;
+ int base;
+
+ /* Return if no other frames. */
+
+ if (regs->wmask == 1)
+ return 0;
+
+ /* Rotate windowmask and skip empty frames. */
+
+ wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb));
+ base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4);
+
+ /* For call8 or call12 frames, we need the previous stack pointer. */
+
+ if ((regs->wmask & 2) == 0)
+ if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12)))
+ goto errout;
+
+ /* Spill frames to stack. */
+
+ while (base < XCHAL_NUM_AREGS / 4) {
+
+ int m = (wm >> base);
+ int inc = 0;
+
+ /* Save registers a4..a7 (call8) or a4...a11 (call12) */
+
+ if (m & 2) { /* call4 */
+ inc = 1;
+
+ } else if (m & 4) { /* call8 */
+ if (copy_to_user(&SPILL_SLOT_CALL8(sp, 4),
+ &regs->areg[(base + 1) * 4], 16))
+ goto errout;
+ inc = 2;
+
+ } else if (m & 8) { /* call12 */
+ if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4),
+ &regs->areg[(base + 1) * 4], 32))
+ goto errout;
+ inc = 3;
+ }
+
+ /* Save current frame a0..a3 under next SP */
+
+ sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS];
+ if (copy_to_user(&SPILL_SLOT(sp, 0), &regs->areg[base * 4], 16))
+ goto errout;
+
+ /* Get current stack pointer for next loop iteration. */
+
+ sp = regs->areg[base * 4 + 1];
+ base += inc;
+ }
+
+ regs->wmask = 1;
+ regs->windowstart = 1 << wb;
+
+ return 0;
+
+errout:
+ return err;
+}
+#else
+static int
+flush_window_regs_user(struct pt_regs *regs)
+{
+ return 0;
+}
+#endif
+
+/*
+ * Note: We don't copy double exception 'regs', 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
+setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs)
+{
+ struct sigcontext __user *sc = &frame->uc.uc_mcontext;
+ struct thread_info *ti = current_thread_info();
+ int err = 0;
+
+#define COPY(x) err |= __put_user(regs->x, &sc->sc_##x)
+ COPY(pc);
+ COPY(ps);
+ COPY(lbeg);
+ COPY(lend);
+ COPY(lcount);
+ COPY(sar);
+#undef COPY
+
+ err |= flush_window_regs_user(regs);
+ err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4);
+ err |= __put_user(0, &sc->sc_xtregs);
+
+ if (err)
+ return err;
+
+#if XTENSA_HAVE_COPROCESSORS
+ coprocessor_flush_release_all(ti);
+ err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp,
+ sizeof (frame->xtregs.cp));
+#endif
+ err |= __copy_to_user(&frame->xtregs.opt, &regs->xtregs_opt,
+ sizeof (xtregs_opt_t));
+ err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user,
+ sizeof (xtregs_user_t));
+
+ err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs);
+
+ return err;
+}
+
+static int
+restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame)
+{
+ struct sigcontext __user *sc = &frame->uc.uc_mcontext;
+ struct thread_info *ti = current_thread_info();
+ unsigned int err = 0;
+ unsigned long ps;
+
+#define COPY(x) err |= __get_user(regs->x, &sc->sc_##x)
+ COPY(pc);
+ COPY(lbeg);
+ COPY(lend);
+ COPY(lcount);
+ COPY(sar);
+#undef COPY
+
+ /* All registers were flushed to stack. Start with a pristine frame. */
+
+ regs->wmask = 1;
+ regs->windowbase = 0;
+ regs->windowstart = 1;
+
+ regs->syscall = NO_SYSCALL; /* disable syscall checks */
+
+ /* 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 & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK);
+
+ /* Additional corruption checks */
+
+ if ((regs->lcount > 0)
+ && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
+ err = 1;
+
+ err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4);
+
+ if (err)
+ return err;
+
+ /* 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. */
+
+#if XTENSA_HAVE_COPROCESSORS
+ coprocessor_release_all(ti);
+ err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp,
+ sizeof (frame->xtregs.cp));
+#endif
+ err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user,
+ sizeof (xtregs_user_t));
+ err |= __copy_from_user(&regs->xtregs_opt, &frame->xtregs.opt,
+ sizeof (xtregs_opt_t));
+
+ return err;
+}
+
+
+/*
+ * Do a signal return; undo the signal stack.
+ */
+
+asmlinkage long xtensa_rt_sigreturn(void)
+{
+ struct pt_regs *regs = current_pt_regs();
+ struct rt_sigframe __user *frame;
+ sigset_t set;
+ int ret;
+
+ /* Always make any pending restarted system calls return -EINTR */
+ current->restart_block.fn = do_no_restart_syscall;
+
+ if (regs->depc > 64)
+ panic("rt_sigreturn in double exception!\n");
+
+ frame = (struct rt_sigframe __user *) regs->areg[1];
+
+ if (!access_ok(frame, sizeof(*frame)))
+ goto badframe;
+
+ if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
+ goto badframe;
+
+ set_current_blocked(&set);
+
+ if (restore_sigcontext(regs, frame))
+ goto badframe;
+
+ ret = regs->areg[2];
+
+ if (restore_altstack(&frame->uc.uc_stack))
+ goto badframe;
+
+ return ret;
+
+badframe:
+ force_sig(SIGSEGV);
+ return 0;
+}
+
+
+
+/*
+ * Set up a signal frame.
+ */
+
+static int
+gen_return_code(unsigned char *codemem)
+{
+ int err = 0;
+
+ /*
+ * 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.
+ */
+
+#if __NR_rt_sigreturn > 255
+# error Generating the MOVI instruction below breaks!
+#endif
+
+#ifdef __XTENSA_EB__ /* Big Endian version */
+ /* Generate instruction: MOVI a2, __NR_rt_sigreturn */
+ err |= __put_user(0x22, &codemem[0]);
+ err |= __put_user(0x0a, &codemem[1]);
+ err |= __put_user(__NR_rt_sigreturn, &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, __NR_rt_sigreturn */
+ err |= __put_user(0x22, &codemem[0]);
+ err |= __put_user(0xa0, &codemem[1]);
+ err |= __put_user(__NR_rt_sigreturn, &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) {
+ __invalidate_icache_range((unsigned long)codemem, 6UL);
+ __flush_invalidate_dcache_range((unsigned long)codemem, 6UL);
+ }
+
+ return err;
+}
+
+
+static int setup_frame(struct ksignal *ksig, sigset_t *set,
+ struct pt_regs *regs)
+{
+ struct rt_sigframe *frame;
+ int err = 0, sig = ksig->sig;
+ unsigned long sp, ra, tp, ps;
+ unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
+ unsigned long handler_fdpic_GOT = 0;
+ unsigned int base;
+ bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) &&
+ (current->personality & FDPIC_FUNCPTRS);
+
+ if (fdpic) {
+ unsigned long __user *fdpic_func_desc =
+ (unsigned long __user *)handler;
+ if (__get_user(handler, &fdpic_func_desc[0]) ||
+ __get_user(handler_fdpic_GOT, &fdpic_func_desc[1]))
+ return -EFAULT;
+ }
+
+ sp = regs->areg[1];
+
+ if ((ksig->ka.sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) {
+ sp = current->sas_ss_sp + current->sas_ss_size;
+ }
+
+ frame = (void *)((sp - sizeof(*frame)) & -16ul);
+
+ if (regs->depc > 64)
+ panic ("Double exception sys_sigreturn\n");
+
+ if (!access_ok(frame, sizeof(*frame))) {
+ return -EFAULT;
+ }
+
+ if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+ err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+ }
+
+ /* Create the user context. */
+
+ err |= __put_user(0, &frame->uc.uc_flags);
+ err |= __put_user(0, &frame->uc.uc_link);
+ err |= __save_altstack(&frame->uc.uc_stack, regs->areg[1]);
+ err |= setup_sigcontext(frame, regs);
+ err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+ if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+ if (fdpic) {
+ unsigned long __user *fdpic_func_desc =
+ (unsigned long __user *)ksig->ka.sa.sa_restorer;
+
+ err |= __get_user(ra, fdpic_func_desc);
+ } else {
+ ra = (unsigned long)ksig->ka.sa.sa_restorer;
+ }
+ } else {
+
+ /* Create sys_rt_sigreturn syscall in stack frame */
+
+ err |= gen_return_code(frame->retcode);
+ ra = (unsigned long) frame->retcode;
+ }
+
+ if (err)
+ return -EFAULT;
+
+ /*
+ * Create signal handler execution context.
+ * Return context not modified until this point.
+ */
+
+ /* Set up registers for signal handler; preserve the threadptr */
+ tp = regs->threadptr;
+ ps = regs->ps;
+ start_thread(regs, handler, (unsigned long)frame);
+
+ /* Set up a stack frame for a call4 if userspace uses windowed ABI */
+ if (ps & PS_WOE_MASK) {
+ base = 4;
+ regs->areg[base] =
+ (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
+ ps = (ps & ~(PS_CALLINC_MASK | PS_OWB_MASK)) |
+ (1 << PS_CALLINC_SHIFT);
+ } else {
+ base = 0;
+ regs->areg[base] = (unsigned long) ra;
+ }
+ regs->areg[base + 2] = (unsigned long) sig;
+ regs->areg[base + 3] = (unsigned long) &frame->info;
+ regs->areg[base + 4] = (unsigned long) &frame->uc;
+ regs->threadptr = tp;
+ regs->ps = ps;
+ if (fdpic)
+ regs->areg[base + 11] = handler_fdpic_GOT;
+
+ pr_debug("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08lx\n",
+ current->comm, current->pid, sig, frame, regs->pc);
+
+ return 0;
+}
+
+/*
+ * 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.
+ */
+static void do_signal(struct pt_regs *regs)
+{
+ struct ksignal ksig;
+
+ task_pt_regs(current)->icountlevel = 0;
+
+ if (get_signal(&ksig)) {
+ int ret;
+
+ /* Are we from a system call? */
+
+ if (regs->syscall != NO_SYSCALL) {
+
+ /* If so, check system call restarting.. */
+
+ switch (regs->areg[2]) {
+ case -ERESTARTNOHAND:
+ case -ERESTART_RESTARTBLOCK:
+ regs->areg[2] = -EINTR;
+ break;
+
+ case -ERESTARTSYS:
+ if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
+ regs->areg[2] = -EINTR;
+ break;
+ }
+ fallthrough;
+ case -ERESTARTNOINTR:
+ regs->areg[2] = regs->syscall;
+ regs->pc -= 3;
+ break;
+
+ default:
+ /* nothing to do */
+ if (regs->areg[2] != 0)
+ break;
+ }
+ }
+
+ /* Whee! Actually deliver the signal. */
+ /* Set up the stack frame */
+ ret = setup_frame(&ksig, sigmask_to_save(), regs);
+ signal_setup_done(ret, &ksig, 0);
+ if (test_thread_flag(TIF_SINGLESTEP))
+ task_pt_regs(current)->icountlevel = 1;
+
+ return;
+ }
+
+ /* Did we come from a system call? */
+ if (regs->syscall != NO_SYSCALL) {
+ /* Restart the system call - no handlers present */
+ switch (regs->areg[2]) {
+ case -ERESTARTNOHAND:
+ case -ERESTARTSYS:
+ case -ERESTARTNOINTR:
+ regs->areg[2] = regs->syscall;
+ regs->pc -= 3;
+ break;
+ case -ERESTART_RESTARTBLOCK:
+ regs->areg[2] = __NR_restart_syscall;
+ regs->pc -= 3;
+ break;
+ }
+ }
+
+ /* If there's no signal to deliver, we just restore the saved mask. */
+ restore_saved_sigmask();
+
+ if (test_thread_flag(TIF_SINGLESTEP))
+ task_pt_regs(current)->icountlevel = 1;
+ return;
+}
+
+void do_notify_resume(struct pt_regs *regs)
+{
+ if (test_thread_flag(TIF_SIGPENDING) ||
+ test_thread_flag(TIF_NOTIFY_SIGNAL))
+ do_signal(regs);
+
+ if (test_thread_flag(TIF_NOTIFY_RESUME))
+ resume_user_mode_work(regs);
+}
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