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-rw-r--r--arch/tile/mm/fault.c905
1 files changed, 905 insertions, 0 deletions
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
new file mode 100644
index 000000000000..9b6b92f07def
--- /dev/null
+++ b/arch/tile/mm/fault.c
@@ -0,0 +1,905 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * 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, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ *
+ * From i386 code copyright (C) 1995 Linus Torvalds
+ */
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/tty.h>
+#include <linux/vt_kern.h> /* For unblank_screen() */
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+#include <linux/hugetlb.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
+
+#include <asm/system.h>
+#include <asm/pgalloc.h>
+#include <asm/sections.h>
+
+#include <arch/interrupts.h>
+
+/*
+ * Unlock any spinlocks which will prevent us from getting the
+ * message out
+ */
+void bust_spinlocks(int yes)
+{
+ int loglevel_save = console_loglevel;
+
+ if (yes) {
+ oops_in_progress = 1;
+ return;
+ }
+ oops_in_progress = 0;
+ /*
+ * OK, the message is on the console. Now we call printk()
+ * without oops_in_progress set so that printk will give klogd
+ * a poke. Hold onto your hats...
+ */
+ console_loglevel = 15; /* NMI oopser may have shut the console up */
+ printk(" ");
+ console_loglevel = loglevel_save;
+}
+
+static noinline void force_sig_info_fault(int si_signo, int si_code,
+ unsigned long address, int fault_num, struct task_struct *tsk)
+{
+ siginfo_t info;
+
+ if (unlikely(tsk->pid < 2)) {
+ panic("Signal %d (code %d) at %#lx sent to %s!",
+ si_signo, si_code & 0xffff, address,
+ tsk->pid ? "init" : "the idle task");
+ }
+
+ info.si_signo = si_signo;
+ info.si_errno = 0;
+ info.si_code = si_code;
+ info.si_addr = (void __user *)address;
+ info.si_trapno = fault_num;
+ force_sig_info(si_signo, &info, tsk);
+}
+
+#ifndef __tilegx__
+/*
+ * Synthesize the fault a PL0 process would get by doing a word-load of
+ * an unaligned address or a high kernel address. Called indirectly
+ * from sys_cmpxchg() in kernel/intvec.S.
+ */
+int _sys_cmpxchg_badaddr(unsigned long address, struct pt_regs *regs)
+{
+ if (address >= PAGE_OFFSET)
+ force_sig_info_fault(SIGSEGV, SEGV_MAPERR, address,
+ INT_DTLB_MISS, current);
+ else
+ force_sig_info_fault(SIGBUS, BUS_ADRALN, address,
+ INT_UNALIGN_DATA, current);
+
+ /*
+ * Adjust pc to point at the actual instruction, which is unusual
+ * for syscalls normally, but is appropriate when we are claiming
+ * that a syscall swint1 caused a page fault or bus error.
+ */
+ regs->pc -= 8;
+
+ /*
+ * Mark this as a caller-save interrupt, like a normal page fault,
+ * so that when we go through the signal handler path we will
+ * properly restore r0, r1, and r2 for the signal handler arguments.
+ */
+ regs->flags |= PT_FLAGS_CALLER_SAVES;
+
+ return 0;
+}
+#endif
+
+static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
+{
+ unsigned index = pgd_index(address);
+ pgd_t *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+
+ pgd += index;
+ pgd_k = init_mm.pgd + index;
+
+ if (!pgd_present(*pgd_k))
+ return NULL;
+
+ pud = pud_offset(pgd, address);
+ pud_k = pud_offset(pgd_k, address);
+ if (!pud_present(*pud_k))
+ return NULL;
+
+ pmd = pmd_offset(pud, address);
+ pmd_k = pmd_offset(pud_k, address);
+ if (!pmd_present(*pmd_k))
+ return NULL;
+ if (!pmd_present(*pmd)) {
+ set_pmd(pmd, *pmd_k);
+ arch_flush_lazy_mmu_mode();
+ } else
+ BUG_ON(pmd_ptfn(*pmd) != pmd_ptfn(*pmd_k));
+ return pmd_k;
+}
+
+/*
+ * Handle a fault on the vmalloc or module mapping area
+ */
+static inline int vmalloc_fault(pgd_t *pgd, unsigned long address)
+{
+ pmd_t *pmd_k;
+ pte_t *pte_k;
+
+ /* Make sure we are in vmalloc area */
+ if (!(address >= VMALLOC_START && address < VMALLOC_END))
+ return -1;
+
+ /*
+ * Synchronize this task's top level page-table
+ * with the 'reference' page table.
+ */
+ pmd_k = vmalloc_sync_one(pgd, address);
+ if (!pmd_k)
+ return -1;
+ if (pmd_huge(*pmd_k))
+ return 0; /* support TILE huge_vmap() API */
+ pte_k = pte_offset_kernel(pmd_k, address);
+ if (!pte_present(*pte_k))
+ return -1;
+ return 0;
+}
+
+/* Wait until this PTE has completed migration. */
+static void wait_for_migration(pte_t *pte)
+{
+ if (pte_migrating(*pte)) {
+ /*
+ * Wait until the migrater fixes up this pte.
+ * We scale the loop count by the clock rate so we'll wait for
+ * a few seconds here.
+ */
+ int retries = 0;
+ int bound = get_clock_rate();
+ while (pte_migrating(*pte)) {
+ barrier();
+ if (++retries > bound)
+ panic("Hit migrating PTE (%#llx) and"
+ " page PFN %#lx still migrating",
+ pte->val, pte_pfn(*pte));
+ }
+ }
+}
+
+/*
+ * It's not generally safe to use "current" to get the page table pointer,
+ * since we might be running an oprofile interrupt in the middle of a
+ * task switch.
+ */
+static pgd_t *get_current_pgd(void)
+{
+ HV_Context ctx = hv_inquire_context();
+ unsigned long pgd_pfn = ctx.page_table >> PAGE_SHIFT;
+ struct page *pgd_page = pfn_to_page(pgd_pfn);
+ BUG_ON(PageHighMem(pgd_page)); /* oops, HIGHPTE? */
+ return (pgd_t *) __va(ctx.page_table);
+}
+
+/*
+ * We can receive a page fault from a migrating PTE at any time.
+ * Handle it by just waiting until the fault resolves.
+ *
+ * It's also possible to get a migrating kernel PTE that resolves
+ * itself during the downcall from hypervisor to Linux. We just check
+ * here to see if the PTE seems valid, and if so we retry it.
+ *
+ * NOTE! We MUST NOT take any locks for this case. We may be in an
+ * interrupt or a critical region, and must do as little as possible.
+ * Similarly, we can't use atomic ops here, since we may be handling a
+ * fault caused by an atomic op access.
+ */
+static int handle_migrating_pte(pgd_t *pgd, int fault_num,
+ unsigned long address,
+ int is_kernel_mode, int write)
+{
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ pte_t pteval;
+
+ if (pgd_addr_invalid(address))
+ return 0;
+
+ pgd += pgd_index(address);
+ pud = pud_offset(pgd, address);
+ if (!pud || !pud_present(*pud))
+ return 0;
+ pmd = pmd_offset(pud, address);
+ if (!pmd || !pmd_present(*pmd))
+ return 0;
+ pte = pmd_huge_page(*pmd) ? ((pte_t *)pmd) :
+ pte_offset_kernel(pmd, address);
+ pteval = *pte;
+ if (pte_migrating(pteval)) {
+ wait_for_migration(pte);
+ return 1;
+ }
+
+ if (!is_kernel_mode || !pte_present(pteval))
+ return 0;
+ if (fault_num == INT_ITLB_MISS) {
+ if (pte_exec(pteval))
+ return 1;
+ } else if (write) {
+ if (pte_write(pteval))
+ return 1;
+ } else {
+ if (pte_read(pteval))
+ return 1;
+ }
+
+ return 0;
+}
+
+/*
+ * This routine is responsible for faulting in user pages.
+ * It passes the work off to one of the appropriate routines.
+ * It returns true if the fault was successfully handled.
+ */
+static int handle_page_fault(struct pt_regs *regs,
+ int fault_num,
+ int is_page_fault,
+ unsigned long address,
+ int write)
+{
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ struct vm_area_struct *vma;
+ unsigned long stack_offset;
+ int fault;
+ int si_code;
+ int is_kernel_mode;
+ pgd_t *pgd;
+
+ /* on TILE, protection faults are always writes */
+ if (!is_page_fault)
+ write = 1;
+
+ is_kernel_mode = (EX1_PL(regs->ex1) != USER_PL);
+
+ tsk = validate_current();
+
+ /*
+ * Check to see if we might be overwriting the stack, and bail
+ * out if so. The page fault code is a relatively likely
+ * place to get trapped in an infinite regress, and once we
+ * overwrite the whole stack, it becomes very hard to recover.
+ */
+ stack_offset = stack_pointer & (THREAD_SIZE-1);
+ if (stack_offset < THREAD_SIZE / 8) {
+ printk(KERN_ALERT "Potential stack overrun: sp %#lx\n",
+ stack_pointer);
+ show_regs(regs);
+ printk(KERN_ALERT "Killing current process %d/%s\n",
+ tsk->pid, tsk->comm);
+ do_group_exit(SIGKILL);
+ }
+
+ /*
+ * Early on, we need to check for migrating PTE entries;
+ * see homecache.c. If we find a migrating PTE, we wait until
+ * the backing page claims to be done migrating, then we procede.
+ * For kernel PTEs, we rewrite the PTE and return and retry.
+ * Otherwise, we treat the fault like a normal "no PTE" fault,
+ * rather than trying to patch up the existing PTE.
+ */
+ pgd = get_current_pgd();
+ if (handle_migrating_pte(pgd, fault_num, address,
+ is_kernel_mode, write))
+ return 1;
+
+ si_code = SEGV_MAPERR;
+
+ /*
+ * 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.
+ *
+ * This verifies that the fault happens in kernel space
+ * and that the fault was not a protection fault.
+ */
+ if (unlikely(address >= TASK_SIZE &&
+ !is_arch_mappable_range(address, 0))) {
+ if (is_kernel_mode && is_page_fault &&
+ vmalloc_fault(pgd, address) >= 0)
+ return 1;
+ /*
+ * Don't take the mm semaphore here. If we fixup a prefetch
+ * fault we could otherwise deadlock.
+ */
+ mm = NULL; /* happy compiler */
+ vma = NULL;
+ goto bad_area_nosemaphore;
+ }
+
+ /*
+ * If we're trying to touch user-space addresses, we must
+ * be either at PL0, or else with interrupts enabled in the
+ * kernel, so either way we can re-enable interrupts here.
+ */
+ local_irq_enable();
+
+ mm = tsk->mm;
+
+ /*
+ * If we're in an interrupt, have no user context or are running in an
+ * atomic region then we must not take the fault.
+ */
+ if (in_atomic() || !mm) {
+ vma = NULL; /* happy compiler */
+ goto bad_area_nosemaphore;
+ }
+
+ /*
+ * When running in the kernel we expect faults to occur only to
+ * addresses in user space. All other faults represent errors in the
+ * kernel and should generate an OOPS. Unfortunately, in the case of an
+ * erroneous fault occurring in a code path which already holds mmap_sem
+ * we will deadlock attempting to validate the fault against the
+ * address space. Luckily the kernel only validly references user
+ * space from well defined areas of code, which are listed in the
+ * exceptions table.
+ *
+ * As the vast majority of faults will be valid we will only perform
+ * the source reference check when there is a possibility of a deadlock.
+ * Attempt to lock the address space, if we cannot we then validate the
+ * source. If this is invalid we can skip the address space check,
+ * thus avoiding the deadlock.
+ */
+ if (!down_read_trylock(&mm->mmap_sem)) {
+ if (is_kernel_mode &&
+ !search_exception_tables(regs->pc)) {
+ vma = NULL; /* happy compiler */
+ goto bad_area_nosemaphore;
+ }
+ 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 (regs->sp < PAGE_OFFSET) {
+ /*
+ * accessing the stack below sp is always a bug.
+ */
+ if (address < regs->sp)
+ 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:
+ si_code = SEGV_ACCERR;
+ if (fault_num == INT_ITLB_MISS) {
+ if (!(vma->vm_flags & VM_EXEC))
+ goto bad_area;
+ } else if (write) {
+#ifdef TEST_VERIFY_AREA
+ if (!is_page_fault && regs->cs == KERNEL_CS)
+ printk("WP fault at "REGFMT"\n", regs->eip);
+#endif
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ } else {
+ if (!is_page_fault || !(vma->vm_flags & VM_READ))
+ goto bad_area;
+ }
+
+ survive:
+ /*
+ * 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, write);
+ if (unlikely(fault & VM_FAULT_ERROR)) {
+ if (fault & VM_FAULT_OOM)
+ goto out_of_memory;
+ else if (fault & VM_FAULT_SIGBUS)
+ goto do_sigbus;
+ BUG();
+ }
+ if (fault & VM_FAULT_MAJOR)
+ tsk->maj_flt++;
+ else
+ tsk->min_flt++;
+
+ /*
+ * If this was an asynchronous fault,
+ * restart the appropriate engine.
+ */
+ switch (fault_num) {
+#if CHIP_HAS_TILE_DMA()
+ case INT_DMATLB_MISS:
+ case INT_DMATLB_MISS_DWNCL:
+ case INT_DMATLB_ACCESS:
+ case INT_DMATLB_ACCESS_DWNCL:
+ __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK);
+ break;
+#endif
+#if CHIP_HAS_SN_PROC()
+ case INT_SNITLB_MISS:
+ case INT_SNITLB_MISS_DWNCL:
+ __insn_mtspr(SPR_SNCTL,
+ __insn_mfspr(SPR_SNCTL) &
+ ~SPR_SNCTL__FRZPROC_MASK);
+ break;
+#endif
+ }
+
+ up_read(&mm->mmap_sem);
+ return 1;
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * Fix it, but check if it's kernel or user first..
+ */
+bad_area:
+ up_read(&mm->mmap_sem);
+
+bad_area_nosemaphore:
+ /* User mode accesses just cause a SIGSEGV */
+ if (!is_kernel_mode) {
+ /*
+ * It's possible to have interrupts off here.
+ */
+ local_irq_enable();
+
+ force_sig_info_fault(SIGSEGV, si_code, address,
+ fault_num, tsk);
+ return 0;
+ }
+
+no_context:
+ /* Are we prepared to handle this kernel fault? */
+ if (fixup_exception(regs))
+ return 0;
+
+/*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+
+ bust_spinlocks(1);
+
+ /* FIXME: no lookup_address() yet */
+#ifdef SUPPORT_LOOKUP_ADDRESS
+ if (fault_num == INT_ITLB_MISS) {
+ pte_t *pte = lookup_address(address);
+
+ if (pte && pte_present(*pte) && !pte_exec_kernel(*pte))
+ printk(KERN_CRIT "kernel tried to execute"
+ " non-executable page - exploit attempt?"
+ " (uid: %d)\n", current->uid);
+ }
+#endif
+ if (address < PAGE_SIZE)
+ printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference\n");
+ else
+ printk(KERN_ALERT "Unable to handle kernel paging request\n");
+ printk(" at virtual address "REGFMT", pc "REGFMT"\n",
+ address, regs->pc);
+
+ show_regs(regs);
+
+ if (unlikely(tsk->pid < 2)) {
+ panic("Kernel page fault running %s!",
+ tsk->pid ? "init" : "the idle task");
+ }
+
+ /*
+ * More FIXME: we should probably copy the i386 here and
+ * implement a generic die() routine. Not today.
+ */
+#ifdef SUPPORT_DIE
+ die("Oops", regs);
+#endif
+ bust_spinlocks(1);
+
+ do_group_exit(SIGKILL);
+
+/*
+ * 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 (is_global_init(tsk)) {
+ yield();
+ down_read(&mm->mmap_sem);
+ goto survive;
+ }
+ printk("VM: killing process %s\n", tsk->comm);
+ if (!is_kernel_mode)
+ do_group_exit(SIGKILL);
+ goto no_context;
+
+do_sigbus:
+ up_read(&mm->mmap_sem);
+
+ /* Kernel mode? Handle exceptions or die */
+ if (is_kernel_mode)
+ goto no_context;
+
+ force_sig_info_fault(SIGBUS, BUS_ADRERR, address, fault_num, tsk);
+ return 0;
+}
+
+#ifndef __tilegx__
+
+extern char sys_cmpxchg[], __sys_cmpxchg_end[];
+extern char __sys_cmpxchg_grab_lock[];
+extern char __start_atomic_asm_code[], __end_atomic_asm_code[];
+
+/*
+ * We return this structure in registers to avoid having to write
+ * additional save/restore code in the intvec.S caller.
+ */
+struct intvec_state {
+ void *handler;
+ unsigned long vecnum;
+ unsigned long fault_num;
+ unsigned long info;
+ unsigned long retval;
+};
+
+/* We must release ICS before panicking or we won't get anywhere. */
+#define ics_panic(fmt, ...) do { \
+ __insn_mtspr(SPR_INTERRUPT_CRITICAL_SECTION, 0); \
+ panic(fmt, __VA_ARGS__); \
+} while (0)
+
+void do_page_fault(struct pt_regs *regs, int fault_num,
+ unsigned long address, unsigned long write);
+
+/*
+ * When we take an ITLB or DTLB fault or access violation in the
+ * supervisor while the critical section bit is set, the hypervisor is
+ * reluctant to write new values into the EX_CONTEXT_1_x registers,
+ * since that might indicate we have not yet squirreled the SPR
+ * contents away and can thus safely take a recursive interrupt.
+ * Accordingly, the hypervisor passes us the PC via SYSTEM_SAVE_1_2.
+ */
+struct intvec_state do_page_fault_ics(struct pt_regs *regs, int fault_num,
+ unsigned long address,
+ unsigned long info)
+{
+ unsigned long pc = info & ~1;
+ int write = info & 1;
+ pgd_t *pgd = get_current_pgd();
+
+ /* Retval is 1 at first since we will handle the fault fully. */
+ struct intvec_state state = {
+ do_page_fault, fault_num, address, write, 1
+ };
+
+ /* Validate that we are plausibly in the right routine. */
+ if ((pc & 0x7) != 0 || pc < PAGE_OFFSET ||
+ (fault_num != INT_DTLB_MISS &&
+ fault_num != INT_DTLB_ACCESS)) {
+ unsigned long old_pc = regs->pc;
+ regs->pc = pc;
+ ics_panic("Bad ICS page fault args:"
+ " old PC %#lx, fault %d/%d at %#lx\n",
+ old_pc, fault_num, write, address);
+ }
+
+ /* We might be faulting on a vmalloc page, so check that first. */
+ if (fault_num != INT_DTLB_ACCESS && vmalloc_fault(pgd, address) >= 0)
+ return state;
+
+ /*
+ * If we faulted with ICS set in sys_cmpxchg, we are providing
+ * a user syscall service that should generate a signal on
+ * fault. We didn't set up a kernel stack on initial entry to
+ * sys_cmpxchg, but instead had one set up by the fault, which
+ * (because sys_cmpxchg never releases ICS) came to us via the
+ * SYSTEM_SAVE_1_2 mechanism, and thus EX_CONTEXT_1_[01] are
+ * still referencing the original user code. We release the
+ * atomic lock and rewrite pt_regs so that it appears that we
+ * came from user-space directly, and after we finish the
+ * fault we'll go back to user space and re-issue the swint.
+ * This way the backtrace information is correct if we need to
+ * emit a stack dump at any point while handling this.
+ *
+ * Must match register use in sys_cmpxchg().
+ */
+ if (pc >= (unsigned long) sys_cmpxchg &&
+ pc < (unsigned long) __sys_cmpxchg_end) {
+#ifdef CONFIG_SMP
+ /* Don't unlock before we could have locked. */
+ if (pc >= (unsigned long)__sys_cmpxchg_grab_lock) {
+ int *lock_ptr = (int *)(regs->regs[ATOMIC_LOCK_REG]);
+ __atomic_fault_unlock(lock_ptr);
+ }
+#endif
+ regs->sp = regs->regs[27];
+ }
+
+ /*
+ * We can also fault in the atomic assembly, in which
+ * case we use the exception table to do the first-level fixup.
+ * We may re-fixup again in the real fault handler if it
+ * turns out the faulting address is just bad, and not,
+ * for example, migrating.
+ */
+ else if (pc >= (unsigned long) __start_atomic_asm_code &&
+ pc < (unsigned long) __end_atomic_asm_code) {
+ const struct exception_table_entry *fixup;
+#ifdef CONFIG_SMP
+ /* Unlock the atomic lock. */
+ int *lock_ptr = (int *)(regs->regs[ATOMIC_LOCK_REG]);
+ __atomic_fault_unlock(lock_ptr);
+#endif
+ fixup = search_exception_tables(pc);
+ if (!fixup)
+ ics_panic("ICS atomic fault not in table:"
+ " PC %#lx, fault %d", pc, fault_num);
+ regs->pc = fixup->fixup;
+ regs->ex1 = PL_ICS_EX1(KERNEL_PL, 0);
+ }
+
+ /*
+ * NOTE: the one other type of access that might bring us here
+ * are the memory ops in __tns_atomic_acquire/__tns_atomic_release,
+ * but we don't have to check specially for them since we can
+ * always safely return to the address of the fault and retry,
+ * since no separate atomic locks are involved.
+ */
+
+ /*
+ * Now that we have released the atomic lock (if necessary),
+ * it's safe to spin if the PTE that caused the fault was migrating.
+ */
+ if (fault_num == INT_DTLB_ACCESS)
+ write = 1;
+ if (handle_migrating_pte(pgd, fault_num, address, 1, write))
+ return state;
+
+ /* Return zero so that we continue on with normal fault handling. */
+ state.retval = 0;
+ return state;
+}
+
+#endif /* !__tilegx__ */
+
+/*
+ * This routine handles page faults. It determines the address, and the
+ * problem, and then passes it handle_page_fault() for normal DTLB and
+ * ITLB issues, and for DMA or SN processor faults when we are in user
+ * space. For the latter, if we're in kernel mode, we just save the
+ * interrupt away appropriately and return immediately. We can't do
+ * page faults for user code while in kernel mode.
+ */
+void do_page_fault(struct pt_regs *regs, int fault_num,
+ unsigned long address, unsigned long write)
+{
+ int is_page_fault;
+
+ /* This case should have been handled by do_page_fault_ics(). */
+ BUG_ON(write & ~1);
+
+#if CHIP_HAS_TILE_DMA()
+ /*
+ * If it's a DMA fault, suspend the transfer while we're
+ * handling the miss; we'll restart after it's handled. If we
+ * don't suspend, it's possible that this process could swap
+ * out and back in, and restart the engine since the DMA is
+ * still 'running'.
+ */
+ if (fault_num == INT_DMATLB_MISS ||
+ fault_num == INT_DMATLB_ACCESS ||
+ fault_num == INT_DMATLB_MISS_DWNCL ||
+ fault_num == INT_DMATLB_ACCESS_DWNCL) {
+ __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__SUSPEND_MASK);
+ while (__insn_mfspr(SPR_DMA_USER_STATUS) &
+ SPR_DMA_STATUS__BUSY_MASK)
+ ;
+ }
+#endif
+
+ /* Validate fault num and decide if this is a first-time page fault. */
+ switch (fault_num) {
+ case INT_ITLB_MISS:
+ case INT_DTLB_MISS:
+#if CHIP_HAS_TILE_DMA()
+ case INT_DMATLB_MISS:
+ case INT_DMATLB_MISS_DWNCL:
+#endif
+#if CHIP_HAS_SN_PROC()
+ case INT_SNITLB_MISS:
+ case INT_SNITLB_MISS_DWNCL:
+#endif
+ is_page_fault = 1;
+ break;
+
+ case INT_DTLB_ACCESS:
+#if CHIP_HAS_TILE_DMA()
+ case INT_DMATLB_ACCESS:
+ case INT_DMATLB_ACCESS_DWNCL:
+#endif
+ is_page_fault = 0;
+ break;
+
+ default:
+ panic("Bad fault number %d in do_page_fault", fault_num);
+ }
+
+ if (EX1_PL(regs->ex1) != USER_PL) {
+ struct async_tlb *async;
+ switch (fault_num) {
+#if CHIP_HAS_TILE_DMA()
+ case INT_DMATLB_MISS:
+ case INT_DMATLB_ACCESS:
+ case INT_DMATLB_MISS_DWNCL:
+ case INT_DMATLB_ACCESS_DWNCL:
+ async = &current->thread.dma_async_tlb;
+ break;
+#endif
+#if CHIP_HAS_SN_PROC()
+ case INT_SNITLB_MISS:
+ case INT_SNITLB_MISS_DWNCL:
+ async = &current->thread.sn_async_tlb;
+ break;
+#endif
+ default:
+ async = NULL;
+ }
+ if (async) {
+
+ /*
+ * No vmalloc check required, so we can allow
+ * interrupts immediately at this point.
+ */
+ local_irq_enable();
+
+ set_thread_flag(TIF_ASYNC_TLB);
+ if (async->fault_num != 0) {
+ panic("Second async fault %d;"
+ " old fault was %d (%#lx/%ld)",
+ fault_num, async->fault_num,
+ address, write);
+ }
+ BUG_ON(fault_num == 0);
+ async->fault_num = fault_num;
+ async->is_fault = is_page_fault;
+ async->is_write = write;
+ async->address = address;
+ return;
+ }
+ }
+
+ handle_page_fault(regs, fault_num, is_page_fault, address, write);
+}
+
+
+#if CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC()
+/*
+ * Check an async_tlb structure to see if a deferred fault is waiting,
+ * and if so pass it to the page-fault code.
+ */
+static void handle_async_page_fault(struct pt_regs *regs,
+ struct async_tlb *async)
+{
+ if (async->fault_num) {
+ /*
+ * Clear async->fault_num before calling the page-fault
+ * handler so that if we re-interrupt before returning
+ * from the function we have somewhere to put the
+ * information from the new interrupt.
+ */
+ int fault_num = async->fault_num;
+ async->fault_num = 0;
+ handle_page_fault(regs, fault_num, async->is_fault,
+ async->address, async->is_write);
+ }
+}
+#endif /* CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC() */
+
+
+/*
+ * This routine effectively re-issues asynchronous page faults
+ * when we are returning to user space.
+ */
+void do_async_page_fault(struct pt_regs *regs)
+{
+ /*
+ * Clear thread flag early. If we re-interrupt while processing
+ * code here, we will reset it and recall this routine before
+ * returning to user space.
+ */
+ clear_thread_flag(TIF_ASYNC_TLB);
+
+#if CHIP_HAS_TILE_DMA()
+ handle_async_page_fault(regs, &current->thread.dma_async_tlb);
+#endif
+#if CHIP_HAS_SN_PROC()
+ handle_async_page_fault(regs, &current->thread.sn_async_tlb);
+#endif
+}
+
+void vmalloc_sync_all(void)
+{
+#ifdef __tilegx__
+ /* Currently all L1 kernel pmd's are static and shared. */
+ BUG_ON(pgd_index(VMALLOC_END) != pgd_index(VMALLOC_START));
+#else
+ /*
+ * Note that races in the updates of insync and start aren't
+ * problematic: insync can only get set bits added, and updates to
+ * start are only improving performance (without affecting correctness
+ * if undone).
+ */
+ static DECLARE_BITMAP(insync, PTRS_PER_PGD);
+ static unsigned long start = PAGE_OFFSET;
+ unsigned long address;
+
+ BUILD_BUG_ON(PAGE_OFFSET & ~PGDIR_MASK);
+ for (address = start; address >= PAGE_OFFSET; address += PGDIR_SIZE) {
+ if (!test_bit(pgd_index(address), insync)) {
+ unsigned long flags;
+ struct list_head *pos;
+
+ spin_lock_irqsave(&pgd_lock, flags);
+ list_for_each(pos, &pgd_list)
+ if (!vmalloc_sync_one(list_to_pgd(pos),
+ address)) {
+ /* Must be at first entry in list. */
+ BUG_ON(pos != pgd_list.next);
+ break;
+ }
+ spin_unlock_irqrestore(&pgd_lock, flags);
+ if (pos != pgd_list.next)
+ set_bit(pgd_index(address), insync);
+ }
+ if (address == start && test_bit(pgd_index(address), insync))
+ start = address + PGDIR_SIZE;
+ }
+#endif
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-14 23:28:19 +0000