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Subject[PATCH v3 18/44] metag: Signal handling
Date
Add signal handling code for metag.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
---
arch/metag/include/uapi/asm/sigcontext.h | 31 +++
arch/metag/include/uapi/asm/siginfo.h | 8 +
arch/metag/kernel/signal.c | 344 ++++++++++++++++++++++++++++++
3 files changed, 383 insertions(+), 0 deletions(-)
create mode 100644 arch/metag/include/uapi/asm/sigcontext.h
create mode 100644 arch/metag/include/uapi/asm/siginfo.h
create mode 100644 arch/metag/kernel/signal.c

diff --git a/arch/metag/include/uapi/asm/sigcontext.h b/arch/metag/include/uapi/asm/sigcontext.h
new file mode 100644
index 0000000..ef79a91
--- /dev/null
+++ b/arch/metag/include/uapi/asm/sigcontext.h
@@ -0,0 +1,31 @@
+#ifndef _ASM_METAG_SIGCONTEXT_H
+#define _ASM_METAG_SIGCONTEXT_H
+
+#include <asm/ptrace.h>
+
+/*
+ * In a sigcontext structure we need to store the active state of the
+ * user process so that it does not get trashed when we call the signal
+ * handler. That not really the same as a user context that we are
+ * going to store on syscall etc.
+ */
+struct sigcontext {
+ struct user_gp_regs regs; /* needs to be first */
+
+ /*
+ * Catch registers describing a memory fault.
+ * If USER_GP_REGS_STATUS_CATCH_BIT is set in regs.status then catch
+ * buffers have been saved and will be replayed on sigreturn.
+ * Clear that bit to discard the catch state instead of replaying it.
+ */
+ struct user_cb_regs cb;
+
+ /*
+ * Read pipeline state. This will get restored on sigreturn.
+ */
+ struct user_rp_state rp;
+
+ unsigned long oldmask;
+};
+
+#endif
diff --git a/arch/metag/include/uapi/asm/siginfo.h b/arch/metag/include/uapi/asm/siginfo.h
new file mode 100644
index 0000000..b2e0c8b
--- /dev/null
+++ b/arch/metag/include/uapi/asm/siginfo.h
@@ -0,0 +1,8 @@
+#ifndef _METAG_SIGINFO_H
+#define _METAG_SIGINFO_H
+
+#define __ARCH_SI_TRAPNO
+
+#include <asm-generic/siginfo.h>
+
+#endif
diff --git a/arch/metag/kernel/signal.c b/arch/metag/kernel/signal.c
new file mode 100644
index 0000000..3be61cf
--- /dev/null
+++ b/arch/metag/kernel/signal.c
@@ -0,0 +1,344 @@
+/*
+ * Copyright (C) 1991,1992 Linus Torvalds
+ * Copyright (C) 2005-2012 Imagination Technologies Ltd.
+ *
+ * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
+ *
+ */
+
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/smp.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 <linux/uaccess.h>
+#include <linux/tracehook.h>
+
+#include <asm/ucontext.h>
+#include <asm/cacheflush.h>
+#include <asm/switch.h>
+#include <asm/syscall.h>
+#include <asm/syscalls.h>
+
+#define REG_FLAGS ctx.SaveMask
+#define REG_RETVAL ctx.DX[0].U0
+#define REG_SYSCALL ctx.DX[0].U1
+#define REG_SP ctx.AX[0].U0
+#define REG_ARG1 ctx.DX[3].U1
+#define REG_ARG2 ctx.DX[3].U0
+#define REG_ARG3 ctx.DX[2].U1
+#define REG_PC ctx.CurrPC
+#define REG_RTP ctx.DX[4].U1
+
+struct rt_sigframe {
+ struct siginfo info;
+ struct ucontext uc;
+ unsigned long retcode[2];
+};
+
+static int restore_sigcontext(struct pt_regs *regs,
+ struct sigcontext __user *sc)
+{
+ int err;
+
+ /* Always make any pending restarted system calls return -EINTR */
+ current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+ err = metag_gp_regs_copyin(regs, 0, sizeof(struct user_gp_regs), NULL,
+ &sc->regs);
+ if (!err)
+ err = metag_cb_regs_copyin(regs, 0,
+ sizeof(struct user_cb_regs), NULL,
+ &sc->cb);
+ if (!err)
+ err = metag_rp_state_copyin(regs, 0,
+ sizeof(struct user_rp_state), NULL,
+ &sc->rp);
+
+ /* This is a user-mode context. */
+ regs->REG_FLAGS |= TBICTX_PRIV_BIT;
+
+ return err;
+}
+
+long sys_rt_sigreturn(void)
+{
+ /* NOTE - Meta stack goes UPWARDS - so we wind the stack back */
+ struct pt_regs *regs = current_pt_regs();
+ struct rt_sigframe __user *frame;
+ sigset_t set;
+
+ frame = (__force struct rt_sigframe __user *)(regs->REG_SP -
+ sizeof(*frame));
+
+ if (!access_ok(VERIFY_READ, 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->uc.uc_mcontext))
+ goto badframe;
+
+ if (restore_altstack(&frame->uc.uc_stack))
+ goto badframe;
+
+ return regs->REG_RETVAL;
+
+badframe:
+ force_sig(SIGSEGV, current);
+
+ return 0;
+}
+
+static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
+ unsigned long mask)
+{
+ int err;
+
+ err = metag_gp_regs_copyout(regs, 0, sizeof(struct user_gp_regs), NULL,
+ &sc->regs);
+
+ if (!err)
+ err = metag_cb_regs_copyout(regs, 0,
+ sizeof(struct user_cb_regs), NULL,
+ &sc->cb);
+ if (!err)
+ err = metag_rp_state_copyout(regs, 0,
+ sizeof(struct user_rp_state), NULL,
+ &sc->rp);
+
+ /* OK, clear that cbuf flag in the old context, or our stored
+ * catch buffer will be restored when we go to call the signal
+ * handler. Also clear out the CBRP RA/RD pipe bit incase
+ * that is pending as well!
+ * Note that as we have already stored this context, these
+ * flags will get restored on sigreturn to their original
+ * state.
+ */
+ regs->REG_FLAGS &= ~(TBICTX_XCBF_BIT | TBICTX_CBUF_BIT |
+ TBICTX_CBRP_BIT);
+
+ /* Clear out the LSM_STEP bits in case we are in the middle of
+ * and MSET/MGET.
+ */
+ regs->ctx.Flags &= ~TXSTATUS_LSM_STEP_BITS;
+
+ err |= __put_user(mask, &sc->oldmask);
+
+ return err;
+}
+
+/*
+ * Determine which stack to use..
+ */
+static void __user *get_sigframe(struct k_sigaction *ka, unsigned long sp,
+ size_t frame_size)
+{
+ /* Meta stacks grows upwards */
+ if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
+ sp = current->sas_ss_sp;
+
+ sp = (sp + 7) & ~7; /* 8byte align stack */
+
+ return (void __user *)sp;
+}
+
+static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+ sigset_t *set, struct pt_regs *regs)
+{
+ struct rt_sigframe __user *frame;
+ int err = -EFAULT;
+ unsigned long code;
+
+ frame = get_sigframe(ka, regs->REG_SP, sizeof(*frame));
+ if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
+ goto out;
+
+ err = copy_siginfo_to_user(&frame->info, info);
+
+ /* Create the ucontext. */
+ err |= __put_user(0, &frame->uc.uc_flags);
+ err |= __put_user(0, (unsigned long __user *)&frame->uc.uc_link);
+ err |= __save_altstack(&frame->uc.uc_stack, regs->REG_SP);
+ err |= setup_sigcontext(&frame->uc.uc_mcontext,
+ regs, set->sig[0]);
+ err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+ if (err)
+ goto out;
+
+ /* Set up to return from userspace. */
+
+ /* MOV D1Re0 (D1.0), #__NR_rt_sigreturn */
+ code = 0x03000004 | (__NR_rt_sigreturn << 3);
+ err |= __put_user(code, (unsigned long __user *)(&frame->retcode[0]));
+
+ /* SWITCH #__METAG_SW_SYS */
+ code = __METAG_SW_ENCODING(SYS);
+ err |= __put_user(code, (unsigned long __user *)(&frame->retcode[1]));
+
+ if (err)
+ goto out;
+
+ /* Set up registers for signal handler */
+ regs->REG_RTP = (unsigned long) frame->retcode;
+ regs->REG_SP = (unsigned long) frame + sizeof(*frame);
+ regs->REG_ARG1 = sig;
+ regs->REG_ARG2 = (unsigned long) &frame->info;
+ regs->REG_ARG3 = (unsigned long) &frame->uc;
+ regs->REG_PC = (unsigned long) ka->sa.sa_handler;
+
+ pr_debug("SIG deliver (%s:%d): sp=%p pc=%08x pr=%08x\n",
+ current->comm, current->pid, frame, regs->REG_PC,
+ regs->REG_RTP);
+
+ /* Now pass size of 'new code' into sigtramp so we can do a more
+ * effective cache flush - directed rather than 'full flush'.
+ */
+ flush_cache_sigtramp(regs->REG_RTP, sizeof(frame->retcode));
+out:
+ if (err) {
+ force_sigsegv(sig, current);
+ return -EFAULT;
+ }
+ return 0;
+}
+
+static void handle_signal(unsigned long sig, siginfo_t *info,
+ struct k_sigaction *ka, struct pt_regs *regs)
+{
+ sigset_t *oldset = sigmask_to_save();
+
+ /* Set up the stack frame */
+ if (setup_rt_frame(sig, ka, info, oldset, regs))
+ return;
+
+ signal_delivered(sig, info, ka, regs, test_thread_flag(TIF_SINGLESTEP));
+}
+
+ /*
+ * Notes for Meta.
+ * We have moved from the old 2.4.9 SH way of using syscall_nr (in the stored
+ * context) to passing in the syscall flag on the stack.
+ * This is because having syscall_nr in our context does not fit with TBX, and
+ * corrupted the stack.
+ */
+static int do_signal(struct pt_regs *regs, int syscall)
+{
+ unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
+ struct k_sigaction ka;
+ siginfo_t info;
+ int signr;
+ int restart = 0;
+
+ /*
+ * By the end of rt_sigreturn the context describes the point that the
+ * signal was taken (which may happen to be just before a syscall if
+ * it's already been restarted). This should *never* be mistaken for a
+ * system call in need of restarting.
+ */
+ if (syscall == __NR_rt_sigreturn)
+ syscall = -1;
+
+ /* Did we come from a system call? */
+ if (syscall >= 0) {
+ continue_addr = regs->REG_PC;
+ restart_addr = continue_addr - 4;
+ retval = regs->REG_RETVAL;
+
+ /*
+ * Prepare for system call restart. We do this here so that a
+ * debugger will see the already changed PC.
+ */
+ switch (retval) {
+ case -ERESTART_RESTARTBLOCK:
+ restart = -2;
+ case -ERESTARTNOHAND:
+ case -ERESTARTSYS:
+ case -ERESTARTNOINTR:
+ ++restart;
+ regs->REG_PC = restart_addr;
+ break;
+ }
+ }
+
+ /*
+ * Get the signal to deliver. When running under ptrace, at this point
+ * the debugger may change all our registers ...
+ */
+ signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+ /*
+ * Depending on the signal settings we may need to revert the decision
+ * to restart the system call. But skip this if a debugger has chosen to
+ * restart at a different PC.
+ */
+ if (regs->REG_PC != restart_addr)
+ restart = 0;
+ if (signr > 0) {
+ if (unlikely(restart)) {
+ if (retval == -ERESTARTNOHAND
+ || retval == -ERESTART_RESTARTBLOCK
+ || (retval == -ERESTARTSYS
+ && !(ka.sa.sa_flags & SA_RESTART))) {
+ regs->REG_RETVAL = -EINTR;
+ regs->REG_PC = continue_addr;
+ }
+ }
+
+ /* Whee! Actually deliver the signal. */
+ handle_signal(signr, &info, &ka, regs);
+ return 0;
+ }
+
+ /* Handlerless -ERESTART_RESTARTBLOCK re-enters via restart_syscall */
+ if (unlikely(restart < 0))
+ regs->REG_SYSCALL = __NR_restart_syscall;
+
+ /*
+ * If there's no signal to deliver, we just put the saved sigmask back.
+ */
+ restore_saved_sigmask();
+
+ return restart;
+}
+
+int do_work_pending(struct pt_regs *regs, unsigned int thread_flags,
+ int syscall)
+{
+ do {
+ if (likely(thread_flags & _TIF_NEED_RESCHED)) {
+ schedule();
+ } else {
+ if (unlikely(!user_mode(regs)))
+ return 0;
+ local_irq_enable();
+ if (thread_flags & _TIF_SIGPENDING) {
+ int restart = do_signal(regs, syscall);
+ if (unlikely(restart)) {
+ /*
+ * Restart without handlers.
+ * Deal with it without leaving
+ * the kernel space.
+ */
+ return restart;
+ }
+ syscall = -1;
+ } else {
+ clear_thread_flag(TIF_NOTIFY_RESUME);
+ tracehook_notify_resume(regs);
+ }
+ }
+ local_irq_disable();
+ thread_flags = current_thread_info()->flags;
+ } while (thread_flags & _TIF_WORK_MASK);
+ return 0;
+}
--
1.7.7.6



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