400 строки
11 KiB
C
400 строки
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* Signal Handling for ARC
|
|
*
|
|
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
|
|
*
|
|
* 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 causing 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 <linux/sched/task_stack.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;
|
|
struct user_regs_struct uregs;
|
|
|
|
uregs.scratch.bta = regs->bta;
|
|
uregs.scratch.lp_start = regs->lp_start;
|
|
uregs.scratch.lp_end = regs->lp_end;
|
|
uregs.scratch.lp_count = regs->lp_count;
|
|
uregs.scratch.status32 = regs->status32;
|
|
uregs.scratch.ret = regs->ret;
|
|
uregs.scratch.blink = regs->blink;
|
|
uregs.scratch.fp = regs->fp;
|
|
uregs.scratch.gp = regs->r26;
|
|
uregs.scratch.r12 = regs->r12;
|
|
uregs.scratch.r11 = regs->r11;
|
|
uregs.scratch.r10 = regs->r10;
|
|
uregs.scratch.r9 = regs->r9;
|
|
uregs.scratch.r8 = regs->r8;
|
|
uregs.scratch.r7 = regs->r7;
|
|
uregs.scratch.r6 = regs->r6;
|
|
uregs.scratch.r5 = regs->r5;
|
|
uregs.scratch.r4 = regs->r4;
|
|
uregs.scratch.r3 = regs->r3;
|
|
uregs.scratch.r2 = regs->r2;
|
|
uregs.scratch.r1 = regs->r1;
|
|
uregs.scratch.r0 = regs->r0;
|
|
uregs.scratch.sp = regs->sp;
|
|
|
|
err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch,
|
|
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;
|
|
struct user_regs_struct uregs;
|
|
|
|
err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
|
|
err |= __copy_from_user(&uregs.scratch,
|
|
&(sf->uc.uc_mcontext.regs.scratch),
|
|
sizeof(sf->uc.uc_mcontext.regs.scratch));
|
|
if (err)
|
|
return err;
|
|
|
|
set_current_blocked(&set);
|
|
regs->bta = uregs.scratch.bta;
|
|
regs->lp_start = uregs.scratch.lp_start;
|
|
regs->lp_end = uregs.scratch.lp_end;
|
|
regs->lp_count = uregs.scratch.lp_count;
|
|
regs->status32 = uregs.scratch.status32;
|
|
regs->ret = uregs.scratch.ret;
|
|
regs->blink = uregs.scratch.blink;
|
|
regs->fp = uregs.scratch.fp;
|
|
regs->r26 = uregs.scratch.gp;
|
|
regs->r12 = uregs.scratch.r12;
|
|
regs->r11 = uregs.scratch.r11;
|
|
regs->r10 = uregs.scratch.r10;
|
|
regs->r9 = uregs.scratch.r9;
|
|
regs->r8 = uregs.scratch.r8;
|
|
regs->r7 = uregs.scratch.r7;
|
|
regs->r6 = uregs.scratch.r6;
|
|
regs->r5 = uregs.scratch.r5;
|
|
regs->r4 = uregs.scratch.r4;
|
|
regs->r3 = uregs.scratch.r3;
|
|
regs->r2 = uregs.scratch.r2;
|
|
regs->r1 = uregs.scratch.r1;
|
|
regs->r0 = uregs.scratch.r0;
|
|
regs->sp = uregs.scratch.sp;
|
|
|
|
return 0;
|
|
}
|
|
|
|
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;
|
|
struct pt_regs *regs = current_pt_regs();
|
|
|
|
/* Always make any pending restarted system calls return -EINTR */
|
|
current->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(sf, sizeof(*sf)))
|
|
goto badframe;
|
|
|
|
if (__get_user(magic, &sf->sigret_magic))
|
|
goto badframe;
|
|
|
|
if (unlikely(is_do_ss_needed(magic)))
|
|
if (restore_altstack(&sf->uc.uc_stack))
|
|
goto badframe;
|
|
|
|
if (restore_usr_regs(regs, sf))
|
|
goto badframe;
|
|
|
|
/* Don't restart from sigreturn */
|
|
syscall_wont_restart(regs);
|
|
|
|
/*
|
|
* Ensure that sigreturn always returns to user mode (in case the
|
|
* regs saved on user stack got fudged between save and sigreturn)
|
|
* Otherwise it is easy to panic the kernel with a custom
|
|
* signal handler and/or restorer which clobberes the status32/ret
|
|
* to return to a bogus location in kernel mode.
|
|
*/
|
|
regs->status32 |= STATUS_U_MASK;
|
|
|
|
return regs->r0;
|
|
|
|
badframe:
|
|
force_sig(SIGSEGV);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Determine which stack to use..
|
|
*/
|
|
static inline void __user *get_sigframe(struct ksignal *ksig,
|
|
struct pt_regs *regs,
|
|
unsigned long framesize)
|
|
{
|
|
unsigned long sp = sigsp(regs->sp, ksig);
|
|
void __user *frame;
|
|
|
|
/* 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(frame, framesize))
|
|
frame = NULL;
|
|
|
|
return frame;
|
|
}
|
|
|
|
static int
|
|
setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
|
|
{
|
|
struct rt_sigframe __user *sf;
|
|
unsigned int magic = 0;
|
|
int err = 0;
|
|
|
|
sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
|
|
if (!sf)
|
|
return 1;
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/*
|
|
* 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(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
|
|
err |= copy_siginfo_to_user(&sf->info, &ksig->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;
|
|
}
|
|
|
|
err |= __put_user(magic, &sf->sigret_magic);
|
|
if (err)
|
|
return err;
|
|
|
|
/* #1 arg to the user Signal handler */
|
|
regs->r0 = ksig->sig;
|
|
|
|
/* setup PC of user space signal handler */
|
|
regs->ret = (unsigned long)ksig->ka.sa.sa_handler;
|
|
|
|
/*
|
|
* handler returns using sigreturn stub provided already by userpsace
|
|
* If not, nuke the process right away
|
|
*/
|
|
if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
|
|
return 1;
|
|
|
|
regs->blink = (unsigned long)ksig->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 -= is_isa_arcv2() ? 2 : 4;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* OK, we're invoking a handler
|
|
*/
|
|
static void
|
|
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
|
|
{
|
|
sigset_t *oldset = sigmask_to_save();
|
|
int failed;
|
|
|
|
/* Set up the stack frame */
|
|
failed = setup_rt_frame(ksig, oldset, regs);
|
|
|
|
signal_setup_done(failed, ksig, 0);
|
|
}
|
|
|
|
void do_signal(struct pt_regs *regs)
|
|
{
|
|
struct ksignal ksig;
|
|
int restart_scall;
|
|
|
|
restart_scall = in_syscall(regs) && syscall_restartable(regs);
|
|
|
|
if (get_signal(&ksig)) {
|
|
if (restart_scall) {
|
|
arc_restart_syscall(&ksig.ka, regs);
|
|
syscall_wont_restart(regs); /* No more restarts */
|
|
}
|
|
handle_signal(&ksig, 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 -= is_isa_arcv2() ? 2 : 4;
|
|
} else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
|
|
regs->r8 = __NR_restart_syscall;
|
|
regs->ret -= is_isa_arcv2() ? 2 : 4;
|
|
}
|
|
syscall_wont_restart(regs); /* No more restarts */
|
|
}
|
|
|
|
/* 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);
|
|
}
|