--- /dev/null
+/*
+ * Signal Handling for ARC
+ *
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * vineetg: Jan 2010 (Restarting of timer related syscalls)
+ *
+ * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
+ * -do_signal() supports TIF_RESTORE_SIGMASK
+ * -do_signal() no loner needs oldset, required by OLD sys_sigsuspend
+ * -sys_rt_sigsuspend() now comes from generic code, so discard arch implemen
+ * -sys_sigsuspend() no longer needs to fudge ptregs, hence that arg removed
+ * -sys_sigsuspend() no longer loops for do_signal(), sets TIF_xxx and leaves
+ * the job to do_signal()
+ *
+ * vineetg: July 2009
+ * -Modified Code to support the uClibc provided userland sigreturn stub
+ * to avoid kernel synthesing it on user stack at runtime, costing TLB
+ * probes and Cache line flushes.
+ *
+ * vineetg: July 2009
+ * -In stash_usr_regs( ) and restore_usr_regs( ), save/restore of user regs
+ * in done in block copy rather than one word at a time.
+ * This saves around 2K of code and improves LMBench lat_sig <catch>
+ *
+ * rajeshwarr: Feb 2009
+ * - Support for Realtime Signals
+ *
+ * vineetg: Aug 11th 2008: Bug #94183
+ * -ViXS were still seeing crashes when using insmod to load drivers.
+ * It turned out that the code to change Execute permssions for TLB entries
+ * of user was not guarded for interrupts (mod_tlb_permission)
+ * This was cauing TLB entries to be overwritten on unrelated indexes
+ *
+ * Vineetg: July 15th 2008: Bug #94183
+ * -Exception happens in Delay slot of a JMP, and before user space resumes,
+ * Signal is delivered (Ctrl + C) = >SIGINT.
+ * setup_frame( ) sets up PC,SP,BLINK to enable user space signal handler
+ * to run, but doesn't clear the Delay slot bit from status32. As a result,
+ * on resuming user mode, signal handler branches off to BTA of orig JMP
+ * -FIX: clear the DE bit from status32 in setup_frame( )
+ *
+ * Rahul Trivedi, Kanika Nema: Codito Technologies 2004
+ */
+
+#include <linux/signal.h>
+#include <linux/ptrace.h>
+#include <linux/personality.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+#include <linux/tracehook.h>
+#include <asm/ucontext.h>
+
+struct rt_sigframe {
+ struct siginfo info;
+ struct ucontext uc;
+#define MAGIC_SIGALTSTK 0x07302004
+ unsigned int sigret_magic;
+};
+
+static int
+stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
+ sigset_t *set)
+{
+ int err;
+ err = __copy_to_user(&(sf->uc.uc_mcontext.regs), regs,
+ sizeof(sf->uc.uc_mcontext.regs.scratch));
+ err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
+
+ return err;
+}
+
+static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
+{
+ sigset_t set;
+ int err;
+
+ err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
+ if (!err)
+ set_current_blocked(&set);
+
+ err |= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs),
+ sizeof(sf->uc.uc_mcontext.regs.scratch));
+
+ return err;
+}
+
+static inline int is_do_ss_needed(unsigned int magic)
+{
+ if (MAGIC_SIGALTSTK == magic)
+ return 1;
+ else
+ return 0;
+}
+
+SYSCALL_DEFINE0(rt_sigreturn)
+{
+ struct rt_sigframe __user *sf;
+ unsigned int magic;
+ int err;
+ struct pt_regs *regs = current_pt_regs();
+
+ /* Always make any pending restarted system calls return -EINTR */
+ current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+ /* Since we stacked the signal on a word boundary,
+ * then 'sp' should be word aligned here. If it's
+ * not, then the user is trying to mess with us.
+ */
+ if (regs->sp & 3)
+ goto badframe;
+
+ sf = (struct rt_sigframe __force __user *)(regs->sp);
+
+ if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
+ goto badframe;
+
+ err = restore_usr_regs(regs, sf);
+ err |= __get_user(magic, &sf->sigret_magic);
+ if (err)
+ goto badframe;
+
+ if (unlikely(is_do_ss_needed(magic)))
+ if (restore_altstack(&sf->uc.uc_stack))
+ goto badframe;
+
+ return regs->r0;
+
+badframe:
+ force_sig(SIGSEGV, current);
+ return 0;
+}
+
+/*
+ * Determine which stack to use..
+ */
+static inline void __user *get_sigframe(struct k_sigaction *ka,
+ struct pt_regs *regs,
+ unsigned long framesize)
+{
+ unsigned long sp = regs->sp;
+ void __user *frame;
+
+ /* This is the X/Open sanctioned signal stack switching */
+ if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
+ sp = current->sas_ss_sp + current->sas_ss_size;
+
+ /* No matter what happens, 'sp' must be word
+ * aligned otherwise nasty things could happen
+ */
+
+ /* ATPCS B01 mandates 8-byte alignment */
+ frame = (void __user *)((sp - framesize) & ~7);
+
+ /* Check that we can actually write to the signal frame */
+ if (!access_ok(VERIFY_WRITE, frame, framesize))
+ frame = NULL;
+
+ return frame;
+}
+
+/*
+ * translate the signal
+ */
+static inline int map_sig(int sig)
+{
+ struct thread_info *thread = current_thread_info();
+ if (thread->exec_domain && thread->exec_domain->signal_invmap
+ && sig < 32)
+ sig = thread->exec_domain->signal_invmap[sig];
+ return sig;
+}
+
+static int
+setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info,
+ sigset_t *set, struct pt_regs *regs)
+{
+ struct rt_sigframe __user *sf;
+ unsigned int magic = 0;
+ int err = 0;
+
+ sf = get_sigframe(ka, regs, sizeof(struct rt_sigframe));
+ if (!sf)
+ return 1;
+
+ /*
+ * SA_SIGINFO requires 3 args to signal handler:
+ * #1: sig-no (common to any handler)
+ * #2: struct siginfo
+ * #3: struct ucontext (completely populated)
+ */
+ if (unlikely(ka->sa.sa_flags & SA_SIGINFO)) {
+ err |= copy_siginfo_to_user(&sf->info, info);
+ err |= __put_user(0, &sf->uc.uc_flags);
+ err |= __put_user(NULL, &sf->uc.uc_link);
+ err |= __save_altstack(&sf->uc.uc_stack, regs->sp);
+
+ /* setup args 2 and 3 for user mode handler */
+ regs->r1 = (unsigned long)&sf->info;
+ regs->r2 = (unsigned long)&sf->uc;
+
+ /*
+ * small optim to avoid unconditonally calling do_sigaltstack
+ * in sigreturn path, now that we only have rt_sigreturn
+ */
+ magic = MAGIC_SIGALTSTK;
+ }
+
+ /*
+ * w/o SA_SIGINFO, struct ucontext is partially populated (only
+ * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
+ * during signal handler execution. This works for SA_SIGINFO as well
+ * although the semantics are now overloaded (the same reg state can be
+ * inspected by userland: but are they allowed to fiddle with it ?
+ */
+ err |= stash_usr_regs(sf, regs, set);
+ err |= __put_user(magic, &sf->sigret_magic);
+ if (err)
+ return err;
+
+ /* #1 arg to the user Signal handler */
+ regs->r0 = map_sig(signo);
+
+ /* setup PC of user space signal handler */
+ regs->ret = (unsigned long)ka->sa.sa_handler;
+
+ /*
+ * handler returns using sigreturn stub provided already by userpsace
+ */
+ BUG_ON(!(ka->sa.sa_flags & SA_RESTORER));
+ regs->blink = (unsigned long)ka->sa.sa_restorer;
+
+ /* User Stack for signal handler will be above the frame just carved */
+ regs->sp = (unsigned long)sf;
+
+ /*
+ * Bug 94183, Clear the DE bit, so that when signal handler
+ * starts to run, it doesn't use BTA
+ */
+ regs->status32 &= ~STATUS_DE_MASK;
+ regs->status32 |= STATUS_L_MASK;
+
+ return err;
+}
+
+static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs)
+{
+ switch (regs->r0) {
+ case -ERESTART_RESTARTBLOCK:
+ case -ERESTARTNOHAND:
+ /*
+ * ERESTARTNOHAND means that the syscall should
+ * only be restarted if there was no handler for
+ * the signal, and since we only get here if there
+ * is a handler, we don't restart
+ */
+ regs->r0 = -EINTR; /* ERESTART_xxx is internal */
+ break;
+
+ case -ERESTARTSYS:
+ /*
+ * ERESTARTSYS means to restart the syscall if
+ * there is no handler or the handler was
+ * registered with SA_RESTART
+ */
+ if (!(ka->sa.sa_flags & SA_RESTART)) {
+ regs->r0 = -EINTR;
+ break;
+ }
+ /* fallthrough */
+
+ case -ERESTARTNOINTR:
+ /*
+ * ERESTARTNOINTR means that the syscall should
+ * be called again after the signal handler returns.
+ * Setup reg state just as it was before doing the trap
+ * r0 has been clobbered with sys call ret code thus it
+ * needs to be reloaded with orig first arg to syscall
+ * in orig_r0. Rest of relevant reg-file:
+ * r8 (syscall num) and (r1 - r7) will be reset to
+ * their orig user space value when we ret from kernel
+ */
+ regs->r0 = regs->orig_r0;
+ regs->ret -= 4;
+ break;
+ }
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+static void
+handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
+ struct pt_regs *regs)
+{
+ sigset_t *oldset = sigmask_to_save();
+ int ret;
+
+ /* Set up the stack frame */
+ ret = setup_rt_frame(sig, ka, info, oldset, regs);
+
+ if (ret)
+ force_sigsegv(sig, current);
+ else
+ signal_delivered(sig, info, ka, regs, 0);
+}
+
+void do_signal(struct pt_regs *regs)
+{
+ struct k_sigaction ka;
+ siginfo_t info;
+ int signr;
+ int restart_scall;
+
+ signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+
+ /* Are we from a system call? */
+ restart_scall = in_syscall(regs);
+
+ if (signr > 0) {
+ if (restart_scall)
+ arc_restart_syscall(&ka, regs);
+
+ handle_signal(signr, &ka, &info, regs);
+ return;
+ }
+
+ if (restart_scall) {
+ /* No handler for syscall: restart it */
+ if (regs->r0 == -ERESTARTNOHAND ||
+ regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) {
+ regs->r0 = regs->orig_r0;
+ regs->ret -= 4;
+ } else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
+ regs->r8 = __NR_restart_syscall;
+ regs->ret -= 4;
+ }
+ }
+
+ /* If there's no signal to deliver, restore the saved sigmask back */
+ restore_saved_sigmask();
+}
+
+void do_notify_resume(struct pt_regs *regs)
+{
+ /*
+ * ASM glue gaurantees that this is only called when returning to
+ * user mode
+ */
+ if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
+ tracehook_notify_resume(regs);
+}
projects / karo-tx-linux.git / commitdiff