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Diffstat (limited to 'arch/xtensa/kernel/signal.c')
| -rw-r--r-- | arch/xtensa/kernel/signal.c | 535 |
1 files changed, 535 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c new file mode 100644 index 0000000000..81f0b106cf --- /dev/null +++ b/arch/xtensa/kernel/signal.c @@ -0,0 +1,535 @@ +/* + * 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/processor.h> +#include <asm/syscall.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), + ®s->areg[(base + 1) * 4], 16)) + goto errout; + inc = 2; + + } else if (m & 8) { /* call12 */ + if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4), + ®s->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), ®s->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, ®s->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(®s->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); +} |