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// SPDX-License-Identifier: GPL-2.0
/*
* fault.c: Page fault handlers for the Sparc.
*
* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
* Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
* Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
*/
#include <asm/head.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/threads.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/perf_event.h>
#include <linux/interrupt.h>
#include <linux/kdebug.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/openprom.h>
#include <asm/oplib.h>
#include <asm/setup.h>
#include <asm/smp.h>
#include <asm/traps.h>
#include "mm_32.h"
int show_unhandled_signals = 1;
static void __noreturn unhandled_fault(unsigned long address,
struct task_struct *tsk,
struct pt_regs *regs)
{
if ((unsigned long) address < PAGE_SIZE) {
printk(KERN_ALERT
"Unable to handle kernel NULL pointer dereference\n");
} else {
printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
address);
}
printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
(tsk->mm ? tsk->mm->context : tsk->active_mm->context));
printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
(tsk->mm ? (unsigned long) tsk->mm->pgd :
(unsigned long) tsk->active_mm->pgd));
die_if_kernel("Oops", regs);
}
asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
unsigned long address)
{
struct pt_regs regs;
unsigned long g2;
unsigned int insn;
int i;
i = search_extables_range(ret_pc, &g2);
switch (i) {
case 3:
/* load & store will be handled by fixup */
return 3;
case 1:
/* store will be handled by fixup, load will bump out */
/* for _to_ macros */
insn = *((unsigned int *) pc);
if ((insn >> 21) & 1)
return 1;
break;
case 2:
/* load will be handled by fixup, store will bump out */
/* for _from_ macros */
insn = *((unsigned int *) pc);
if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
return 2;
break;
default:
break;
}
memset(®s, 0, sizeof(regs));
regs.pc = pc;
regs.npc = pc + 4;
__asm__ __volatile__(
"rd %%psr, %0\n\t"
"nop\n\t"
"nop\n\t"
"nop\n" : "=r" (regs.psr));
unhandled_fault(address, current, ®s);
/* Not reached */
return 0;
}
static inline void
show_signal_msg(struct pt_regs *regs, int sig, int code,
unsigned long address, struct task_struct *tsk)
{
if (!unhandled_signal(tsk, sig))
return;
if (!printk_ratelimit())
return;
printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
tsk->comm, task_pid_nr(tsk), address,
(void *)regs->pc, (void *)regs->u_regs[UREG_I7],
(void *)regs->u_regs[UREG_FP], code);
print_vma_addr(KERN_CONT " in ", regs->pc);
printk(KERN_CONT "\n");
}
static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
unsigned long addr)
{
if (unlikely(show_unhandled_signals))
show_signal_msg(regs, sig, code,
addr, current);
force_sig_fault(sig, code, (void __user *) addr, 0);
}
static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
{
unsigned int insn;
if (text_fault)
return regs->pc;
if (regs->psr & PSR_PS)
insn = *(unsigned int *) regs->pc;
else
__get_user(insn, (unsigned int *) regs->pc);
return safe_compute_effective_address(regs, insn);
}
static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
int text_fault)
{
unsigned long addr = compute_si_addr(regs, text_fault);
__do_fault_siginfo(code, sig, regs, addr);
}
asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
unsigned long address)
{
struct vm_area_struct *vma;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
unsigned int fixup;
unsigned long g2;
int from_user = !(regs->psr & PSR_PS);
int code;
vm_fault_t fault;
unsigned int flags = FAULT_FLAG_DEFAULT;
if (text_fault)
address = regs->pc;
/*
* We fault-in kernel-space virtual memory on-demand. The
* 'reference' page table is init_mm.pgd.
*
* NOTE! We MUST NOT take any locks for this case. We may
* be in an interrupt or a critical region, and should
* only copy the information from the master page table,
* nothing more.
*/
code = SEGV_MAPERR;
if (address >= TASK_SIZE)
goto vmalloc_fault;
/*
* If we're in an interrupt or have no user
* context, we must not take the fault..
*/
if (pagefault_disabled() || !mm)
goto no_context;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
retry:
mmap_read_lock(mm);
if (!from_user && address >= PAGE_OFFSET)
goto bad_area;
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
code = SEGV_ACCERR;
if (write) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
/* Allow reads even for write-only mappings */
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
if (from_user)
flags |= FAULT_FLAG_USER;
if (write)
flags |= FAULT_FLAG_WRITE;
/*
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(vma, address, flags, regs);
if (fault_signal_pending(fault, regs))
return;
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
else if (fault & VM_FAULT_SIGSEGV)
goto bad_area;
else if (fault & VM_FAULT_SIGBUS)
goto do_sigbus;
BUG();
}
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_RETRY) {
flags |= FAULT_FLAG_TRIED;
/* No need to mmap_read_unlock(mm) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
mmap_read_unlock(mm);
return;
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