struct vm_area_struct *vma = NULL;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
- int si_code = SEGV_MAPERR;
- int ret;
- vm_fault_t fault;
- int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
- unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+ int sig, si_code = SEGV_MAPERR;
+ unsigned int write = 0, exec = 0, mask;
+ vm_fault_t fault = VM_FAULT_SIGSEGV; /* handle_mm_fault() output */
+ unsigned int flags; /* handle_mm_fault() input */
/*
- * 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.
*/
if (address >= VMALLOC_START && !user_mode(regs)) {
- ret = handle_kernel_vaddr_fault(address);
- if (unlikely(ret))
+ if (unlikely(handle_kernel_vaddr_fault(address)))
goto no_context;
else
return;
if (faulthandler_disabled() || !mm)
goto no_context;
+ if (regs->ecr_cause & ECR_C_PROTV_STORE) /* ST/EX */
+ write = 1;
+ else if ((regs->ecr_vec == ECR_V_PROTV) &&
+ (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
+ exec = 1;
+
+ flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
+ if (write)
+ flags |= FAULT_FLAG_WRITE;
+
retry:
down_read(&mm->mmap_sem);
+
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;
+ if (unlikely(address < vma->vm_start)) {
+ if (!(vma->vm_flags & VM_GROWSDOWN) || expand_stack(vma, address))
+ goto bad_area;
+ }
/*
- * Ok, we have a good vm_area for this memory access, so
- * we can handle it..
+ * vm_area is good, now check permissions for this memory access
*/
-good_area:
- si_code = SEGV_ACCERR;
-
- /* Handle protection violation, execute on heap or stack */
-
- if ((regs->ecr_vec == ECR_V_PROTV) &&
- (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
+ mask = VM_READ;
+ if (write)
+ mask = VM_WRITE;
+ if (exec)
+ mask = VM_EXEC;
+
+ if (!(vma->vm_flags & mask)) {
+ si_code = SEGV_ACCERR;
goto bad_area;
-
- if (write) {
- if (!(vma->vm_flags & VM_WRITE))
- goto bad_area;
- flags |= FAULT_FLAG_WRITE;
- } else {
- if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
- 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(vma, address, flags);
- if (fatal_signal_pending(current)) {
+ /*
+ * Fault retry nuances
+ */
+ if (unlikely(fault & VM_FAULT_RETRY)) {
/*
- * if fault retry, mmap_sem already relinquished by core mm
- * so OK to return to user mode (with signal handled first)
+ * If fault needs to be retried, handle any pending signals
+ * first (by returning to user mode).
+ * mmap_sem already relinquished by core mm for RETRY case
*/
- if (fault & VM_FAULT_RETRY) {
+ if (fatal_signal_pending(current)) {
if (!user_mode(regs))
goto no_context;
return;
}
- }
-
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
-
- if (likely(!(fault & VM_FAULT_ERROR))) {
+ /*
+ * retry state machine
+ */
if (flags & FAULT_FLAG_ALLOW_RETRY) {
- /* To avoid updating stats twice for retry case */
- if (fault & VM_FAULT_MAJOR) {
- tsk->maj_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
- regs, address);
- } else {
- tsk->min_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
- regs, address);
- }
-
- if (fault & VM_FAULT_RETRY) {
- flags &= ~FAULT_FLAG_ALLOW_RETRY;
- flags |= FAULT_FLAG_TRIED;
- goto retry;
- }
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
+ goto retry;
}
-
- /* Fault Handled Gracefully */
- up_read(&mm->mmap_sem);
- return;
}
- 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;
-
- /* no man's land */
- BUG();
+bad_area:
+ up_read(&mm->mmap_sem);
/*
- * Something tried to access memory that isn't in our memory map..
- * Fix it, but check if it's kernel or user first..
+ * Major/minor page fault accounting
+ * (in case of retry we only land here once)
*/
-bad_area:
- up_read(&mm->mmap_sem);
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
- /* User mode accesses just cause a SIGSEGV */
- if (user_mode(regs)) {
- tsk->thread.fault_address = address;
- force_sig_fault(SIGSEGV, si_code, (void __user *)address);
- return;
- }
+ if (likely(!(fault & VM_FAULT_ERROR))) {
+ if (fault & VM_FAULT_MAJOR) {
+ tsk->maj_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+ regs, address);
+ } else {
+ tsk->min_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+ regs, address);
+ }
-no_context:
- /* Are we prepared to handle this kernel fault?
- *
- * (The kernel has valid exception-points in the source
- * when it accesses user-memory. When it fails in one
- * of those points, we find it in a table and do a jump
- * to some fixup code that loads an appropriate error
- * code)
- */
- if (fixup_exception(regs))
+ /* Normal return path: fault Handled Gracefully */
return;
+ }
- die("Oops", regs, address);
-
-out_of_memory:
- up_read(&mm->mmap_sem);
+ if (!user_mode(regs))
+ goto no_context;
- if (user_mode(regs)) {
+ if (fault & VM_FAULT_OOM) {
pagefault_out_of_memory();
return;
}
- goto no_context;
+ if (fault & VM_FAULT_SIGBUS) {
+ sig = SIGBUS;
+ si_code = BUS_ADRERR;
+ }
+ else {
+ sig = SIGSEGV;
+ }
-do_sigbus:
- up_read(&mm->mmap_sem);
+ tsk->thread.fault_address = address;
+ force_sig_fault(sig, si_code, (void __user *)address);
+ return;
- if (!user_mode(regs))
- goto no_context;
+no_context:
+ if (fixup_exception(regs))
+ return;
- tsk->thread.fault_address = address;
- force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
+ die("Oops", regs, address);
}
projects / linux-2.6-microblaze.git / blobdiff