linux/arch/arm64/kernel/signal.c
Catalin Marinas 2c020ed8d1 arm64: Signal handling support
This patch adds support for signal handling. The sigreturn is done via
VDSO, introduced by a previous patch. The SA_RESTORER is still defined
as it is required for 32-bit (compat) support but it is not to be used
for 64-bit applications.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
2012-09-17 13:42:10 +01:00

438 lines
11 KiB
C

/*
* Based on arch/arm/kernel/signal.c
*
* Copyright (C) 1995-2009 Russell King
* Copyright (C) 2012 ARM Ltd.
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/personality.h>
#include <linux/freezer.h>
#include <linux/uaccess.h>
#include <linux/tracehook.h>
#include <linux/ratelimit.h>
#include <asm/compat.h>
#include <asm/debug-monitors.h>
#include <asm/elf.h>
#include <asm/cacheflush.h>
#include <asm/ucontext.h>
#include <asm/unistd.h>
#include <asm/fpsimd.h>
#include <asm/signal32.h>
#include <asm/vdso.h>
/*
* Do a signal return; undo the signal stack. These are aligned to 128-bit.
*/
struct rt_sigframe {
struct siginfo info;
struct ucontext uc;
};
static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
{
struct fpsimd_state *fpsimd = &current->thread.fpsimd_state;
int err;
/* dump the hardware registers to the fpsimd_state structure */
fpsimd_save_state(fpsimd);
/* copy the FP and status/control registers */
err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
__put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
__put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
/* copy the magic/size information */
__put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
__put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
return err ? -EFAULT : 0;
}
static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
{
struct fpsimd_state fpsimd;
__u32 magic, size;
int err = 0;
/* check the magic/size information */
__get_user_error(magic, &ctx->head.magic, err);
__get_user_error(size, &ctx->head.size, err);
if (err)
return -EFAULT;
if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
return -EINVAL;
/* copy the FP and status/control registers */
err = __copy_from_user(fpsimd.vregs, ctx->vregs,
sizeof(fpsimd.vregs));
__get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
__get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
/* load the hardware registers from the fpsimd_state structure */
if (!err) {
preempt_disable();
fpsimd_load_state(&fpsimd);
preempt_enable();
}
return err ? -EFAULT : 0;
}
static int restore_sigframe(struct pt_regs *regs,
struct rt_sigframe __user *sf)
{
sigset_t set;
int i, err;
struct aux_context __user *aux =
(struct aux_context __user *)sf->uc.uc_mcontext.__reserved;
err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
if (err == 0)
set_current_blocked(&set);
for (i = 0; i < 31; i++)
__get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
err);
__get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
__get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
__get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
/*
* Avoid sys_rt_sigreturn() restarting.
*/
regs->syscallno = ~0UL;
err |= !valid_user_regs(&regs->user_regs);
if (err == 0)
err |= restore_fpsimd_context(&aux->fpsimd);
return err;
}
asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
/* 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 128-bit boundary, then 'sp' should
* be word aligned here.
*/
if (regs->sp & 15)
goto badframe;
frame = (struct rt_sigframe __user *)regs->sp;
if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
goto badframe;
if (restore_sigframe(regs, frame))
goto badframe;
if (do_sigaltstack(&frame->uc.uc_stack,
NULL, regs->sp) == -EFAULT)
goto badframe;
return regs->regs[0];
badframe:
if (show_unhandled_signals)
pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
current->comm, task_pid_nr(current), __func__,
regs->pc, regs->sp);
force_sig(SIGSEGV, current);
return 0;
}
asmlinkage long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
unsigned long sp)
{
return do_sigaltstack(uss, uoss, sp);
}
static int setup_sigframe(struct rt_sigframe __user *sf,
struct pt_regs *regs, sigset_t *set)
{
int i, err = 0;
struct aux_context __user *aux =
(struct aux_context __user *)sf->uc.uc_mcontext.__reserved;
for (i = 0; i < 31; i++)
__put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
err);
__put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
__put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
__put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
__put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
if (err == 0)
err |= preserve_fpsimd_context(&aux->fpsimd);
/* set the "end" magic */
__put_user_error(0, &aux->end.magic, err);
__put_user_error(0, &aux->end.size, err);
return err;
}
static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
int framesize)
{
unsigned long sp, sp_top;
void __user *frame;
sp = sp_top = regs->sp;
/*
* This is the X/Open sanctioned signal stack switching.
*/
if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
sp = sp_top = current->sas_ss_sp + current->sas_ss_size;
/* room for stack frame (FP, LR) */
sp -= 16;
sp = (sp - framesize) & ~15;
frame = (void __user *)sp;
/*
* Check that we can actually write to the signal frame.
*/
if (!access_ok(VERIFY_WRITE, frame, sp_top - sp))
frame = NULL;
return frame;
}
static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
void __user *frame, int usig)
{
int err = 0;
__sigrestore_t sigtramp;
unsigned long __user *sp = (unsigned long __user *)regs->sp;
/* set up the stack frame */
__put_user_error(regs->regs[29], sp - 2, err);
__put_user_error(regs->regs[30], sp - 1, err);
regs->regs[0] = usig;
regs->regs[29] = regs->sp - 16;
regs->sp = (unsigned long)frame;
regs->pc = (unsigned long)ka->sa.sa_handler;
if (ka->sa.sa_flags & SA_RESTORER)
sigtramp = ka->sa.sa_restorer;
else
sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
regs->regs[30] = (unsigned long)sigtramp;
return err;
}
static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
stack_t stack;
int err = 0;
frame = get_sigframe(ka, regs, sizeof(*frame));
if (!frame)
return 1;
__put_user_error(0, &frame->uc.uc_flags, err);
__put_user_error(NULL, &frame->uc.uc_link, err);
memset(&stack, 0, sizeof(stack));
stack.ss_sp = (void __user *)current->sas_ss_sp;
stack.ss_flags = sas_ss_flags(regs->sp);
stack.ss_size = current->sas_ss_size;
err |= __copy_to_user(&frame->uc.uc_stack, &stack, sizeof(stack));
err |= setup_sigframe(frame, regs, set);
if (err == 0)
err = setup_return(regs, ka, frame, usig);
if (err == 0 && ka->sa.sa_flags & SA_SIGINFO) {
err |= copy_siginfo_to_user(&frame->info, info);
regs->regs[1] = (unsigned long)&frame->info;
regs->regs[2] = (unsigned long)&frame->uc;
}
return err;
}
static void setup_restart_syscall(struct pt_regs *regs)
{
if (is_compat_task())
compat_setup_restart_syscall(regs);
else
regs->regs[8] = __NR_restart_syscall;
}
/*
* OK, we're invoking a handler
*/
static void handle_signal(unsigned long sig, struct k_sigaction *ka,
siginfo_t *info, struct pt_regs *regs)
{
struct thread_info *thread = current_thread_info();
struct task_struct *tsk = current;
sigset_t *oldset = sigmask_to_save();
int usig = sig;
int ret;
/*
* translate the signal
*/
if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
usig = thread->exec_domain->signal_invmap[usig];
/*
* Set up the stack frame
*/
if (is_compat_task()) {
if (ka->sa.sa_flags & SA_SIGINFO)
ret = compat_setup_rt_frame(usig, ka, info, oldset,
regs);
else
ret = compat_setup_frame(usig, ka, oldset, regs);
} else {
ret = setup_rt_frame(usig, ka, info, oldset, regs);
}
/*
* Check that the resulting registers are actually sane.
*/
ret |= !valid_user_regs(&regs->user_regs);
if (ret != 0) {
force_sigsegv(sig, tsk);
return;
}
/*
* Fast forward the stepping logic so we step into the signal
* handler.
*/
user_fastforward_single_step(tsk);
signal_delivered(sig, info, ka, regs, 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)
{
unsigned long continue_addr = 0, restart_addr = 0;
struct k_sigaction ka;
siginfo_t info;
int signr, retval = 0;
int syscall = (int)regs->syscallno;
/*
* If we were from a system call, check for system call restarting...
*/
if (syscall >= 0) {
continue_addr = regs->pc;
restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
retval = regs->regs[0];
/*
* Avoid additional syscall restarting via ret_to_user.
*/
regs->syscallno = ~0UL;
/*
* Prepare for system call restart. We do this here so that a
* debugger will see the already changed PC.
*/
switch (retval) {
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
case -ERESTART_RESTARTBLOCK:
regs->regs[0] = regs->orig_x0;
regs->pc = restart_addr;
break;
}
}
/*
* Get the signal to deliver. When running under ptrace, at this point
* the debugger may change all of our registers.
*/
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
/*
* 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->pc == restart_addr &&
(retval == -ERESTARTNOHAND ||
retval == -ERESTART_RESTARTBLOCK ||
(retval == -ERESTARTSYS &&
!(ka.sa.sa_flags & SA_RESTART)))) {
regs->regs[0] = -EINTR;
regs->pc = continue_addr;
}
handle_signal(signr, &ka, &info, regs);
return;
}
/*
* Handle restarting a different system call. As above, if a debugger
* has chosen to restart at a different PC, ignore the restart.
*/
if (syscall >= 0 && regs->pc == restart_addr) {
if (retval == -ERESTART_RESTARTBLOCK)
setup_restart_syscall(regs);
user_rewind_single_step(current);
}
restore_saved_sigmask();
}
asmlinkage void do_notify_resume(struct pt_regs *regs,
unsigned int thread_flags)
{
if (thread_flags & _TIF_SIGPENDING)
do_signal(regs);
if (thread_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
}
}