Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 | /*
* Meta page fault handling.
*
* Copyright (C) 2005-2012 Imagination Technologies Ltd.
*/
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <asm/tlbflush.h>
#include <asm/mmu.h>
#include <asm/traps.h>
/* Clear any pending catch buffer state. */
static void clear_cbuf_entry(struct pt_regs *regs, unsigned long addr,
unsigned int trapno)
{
PTBICTXEXTCB0 cbuf = regs->extcb0;
switch (trapno) {
/* Instruction fetch faults leave no catch buffer state. */
case TBIXXF_SIGNUM_IGF:
case TBIXXF_SIGNUM_IPF:
return;
default:
if (cbuf[0].CBAddr == addr) {
cbuf[0].CBAddr = 0;
cbuf[0].CBFlags &= ~TXCATCH0_FAULT_BITS;
/* And, as this is the ONLY catch entry, we
* need to clear the cbuf bit from the context!
*/
regs->ctx.SaveMask &= ~(TBICTX_CBUF_BIT |
TBICTX_XCBF_BIT);
return;
}
pr_err("Failed to clear cbuf entry!\n");
}
}
int show_unhandled_signals = 1;
int do_page_fault(struct pt_regs *regs, unsigned long address,
unsigned int write_access, unsigned int trapno)
{
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma, *prev_vma;
siginfo_t info;
int fault;
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
tsk = current;
if ((address >= VMALLOC_START) && (address < VMALLOC_END)) {
/*
* Synchronize this task's top level page-table
* with the 'reference' page table.
*
* Do _not_ use "tsk" here. We might be inside
* an interrupt in the middle of a task switch..
*/
int offset = pgd_index(address);
pgd_t *pgd, *pgd_k;
pud_t *pud, *pud_k;
pmd_t *pmd, *pmd_k;
pte_t *pte_k;
pgd = ((pgd_t *)mmu_get_base()) + offset;
pgd_k = swapper_pg_dir + offset;
/* This will never happen with the folded page table. */
if (!pgd_present(*pgd)) {
if (!pgd_present(*pgd_k))
goto bad_area_nosemaphore;
set_pgd(pgd, *pgd_k);
return 0;
}
pud = pud_offset(pgd, address);
pud_k = pud_offset(pgd_k, address);
if (!pud_present(*pud_k))
goto bad_area_nosemaphore;
set_pud(pud, *pud_k);
pmd = pmd_offset(pud, address);
pmd_k = pmd_offset(pud_k, address);
if (!pmd_present(*pmd_k))
goto bad_area_nosemaphore;
set_pmd(pmd, *pmd_k);
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto bad_area_nosemaphore;
/* May only be needed on Chorus2 */
flush_tlb_all();
return 0;
}
mm = tsk->mm;
if (in_atomic() || !mm)
goto no_context;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
retry:
down_read(&mm->mmap_sem);
vma = find_vma_prev(mm, address, &prev_vma);
if (!vma || address < vma->vm_start)
goto check_expansion;
good_area:
if (write_access) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
} else {
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto bad_area;
}
/*
* 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(mm, vma, address, flags);
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
return 0;
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_MAJOR)
tsk->maj_flt++;
else
tsk->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
flags |= FAULT_FLAG_TRIED;
/*
* No need to up_read(&mm->mmap_sem) as we would
* have already released it in __lock_page_or_retry
* in mm/filemap.c.
*/
goto retry;
}
}
up_read(&mm->mmap_sem);
return 0;
check_expansion:
vma = prev_vma;
if (vma && (expand_stack(vma, address) == 0))
goto good_area;
bad_area:
up_read(&mm->mmap_sem);
bad_area_nosemaphore:
if (user_mode(regs)) {
info.si_signo = SIGSEGV;
info.si_errno = 0;
info.si_code = SEGV_MAPERR;
info.si_addr = (__force void __user *)address;
info.si_trapno = trapno;
if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
printk_ratelimit()) {
pr_info("%s%s[%d]: segfault at %lx pc %08x sp %08x write %d trap %#x (%s)",
task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
tsk->comm, task_pid_nr(tsk), address,
regs->ctx.CurrPC, regs->ctx.AX[0].U0,
write_access, trapno, trap_name(trapno));
print_vma_addr(" in ", regs->ctx.CurrPC);
print_vma_addr(" rtp in ", regs->ctx.DX[4].U1);
printk("\n");
show_regs(regs);
}
force_sig_info(SIGSEGV, &info, tsk);
return 1;
}
goto no_context;
do_sigbus:
up_read(&mm->mmap_sem);
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
info.si_signo = SIGBUS;
info.si_errno = 0;
info.si_code = BUS_ADRERR;
info.si_addr = (__force void __user *)address;
info.si_trapno = trapno;
force_sig_info(SIGBUS, &info, tsk);
/* Kernel mode? Handle exceptions or die */
if (!user_mode(regs))
goto no_context;
return 1;
/*
* We ran out of memory, or some other thing happened to us that made
* us unable to handle the page fault gracefully.
*/
out_of_memory:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
pagefault_out_of_memory();
return 1;
}
no_context:
/* Are we prepared to handle this kernel fault? */
if (fixup_exception(regs)) {
clear_cbuf_entry(regs, address, trapno);
return 1;
}
die("Oops", regs, (write_access << 15) | trapno, address);
do_exit(SIGKILL);
}
|