Commit 262d96b0 authored by James Hogan's avatar James Hogan
Browse files

metag: Signal handling



Add signal handling code for metag.
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
parent c438b58e
#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
#ifndef _METAG_SIGINFO_H
#define _METAG_SIGINFO_H
#define __ARCH_SI_TRAPNO
#include <asm-generic/siginfo.h>
#endif
/*
* 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;
}
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