patch-2.4.22 linux-2.4.22/arch/sh64/mm/tlbmiss.c

• Lines: 284
• Date: 2003-08-25 04:44:40.000000000 -0700
• Orig file: linux-2.4.21/arch/sh64/mm/tlbmiss.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.21/arch/sh64/mm/tlbmiss.c linux-2.4.22/arch/sh64/mm/tlbmiss.c
@@ -0,0 +1,283 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * arch/sh64/mm/tlbmiss.c
+ *
+ * Original code from fault.c
+ * Copyright (C) 2000, 2001  Paolo Alberelli
+ *
+ * Fast PTE->TLB refill path
+ * Copyright (C) 2003 Richard.Curnow@superh.com
+ *
+ * IMPORTANT NOTES :
+ * The do_fast_page_fault function is called from a context in entry.S where very few registers
+ * have been saved.  In particular, the code in this file must be compiled not to use ANY
+ * caller-save regiseters that are not part of the restricted save set.  Also, it means that
+ * code in this file must not make calls to functions elsewhere in the kernel, or else the
+ * excepting context will see corruption in its caller-save registers.  Plus, the entry.S save
+ * area is non-reentrant, so this code has to run with SR.BL==1, i.e. no interrupts taken inside
+ * it and panic on any exception.
+ *
+ */
+
+#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 <asm/system.h>
+#include <asm/tlb.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/pgalloc.h>
+#include <asm/hardirq.h>
+#include <asm/mmu_context.h>
+#include <asm/registers.h>		/* required by inline asm statements */
+
+/* Callable from fault.c, so not static */
+__inline__ void __do_tlb_refill(unsigned long address, 
+                            unsigned long long is_text_not_data, pte_t *pte)
+{
+	unsigned long long ptel;
+	unsigned long long pteh=0;
+	struct tlb_info *tlbp;
+	unsigned long long next;
+
+	/* Get PTEL first */
+	ptel = pte_val(*pte);
+
+	/*
+	 * Set PTEH register
+	 */
+	pteh = address & MMU_VPN_MASK;
+
+	/* Sign extend based on neff. */
+#if (NEFF == 32)
+	/* Faster sign extension */
+	pteh = (unsigned long long)(signed long long)(signed long)pteh;
+#else
+	/* General case */
+	pteh = (pteh & NEFF_SIGN) ? (pteh | NEFF_MASK) : pteh;
+#endif
+
+	/* Set the ASID. */
+	pteh |= get_asid() << PTEH_ASID_SHIFT;
+     
+	pteh |= PTEH_VALID;
+
+	/* Set PTEL register, set_pte has performed the sign extension */
+	ptel &= _PAGE_FLAGS_HARDWARE_MASK; /* drop software flags */
+	ptel |= _PAGE_FLAGS_HARDWARE_DEFAULT; /* add default flags */
+
+	tlbp = is_text_not_data ? &(cpu_data->itlb) : &(cpu_data->dtlb);
+	next = tlbp->next;
+	__flush_tlb_slot(next);
+	asm volatile ("putcfg %0,1,%2\n\n\t"
+		      "putcfg %0,0,%1\n"
+		      :  : "r" (next), "r" (pteh), "r" (ptel) );
+
+	next += TLB_STEP;
+	if (next > tlbp->last) next = tlbp->first;
+	tlbp->next = next;
+
+}
+
+static int handle_vmalloc_fault(struct mm_struct *mm, unsigned long protection_flags, 
+                                unsigned long long textaccess,
+				unsigned long address)
+{
+	pgd_t *dir;
+	pmd_t *pmd;
+	static pte_t *pte;
+	pte_t entry;
+
+	dir = pgd_offset_k(address);
+	pmd = pmd_offset(dir, address);
+
+	
+	if (pmd_none(*pmd)) {
+		return 0;
+	}
+	if (pmd_bad(*pmd)) {
+		pmd_clear(pmd);
+		return 0;
+	}
+	pte = pte_offset(pmd, address);
+	entry = *pte;
+	if (pte_none(entry) || !pte_present(entry)) {
+		return 0;
+	}
+
+	if ((pte_val(entry) & protection_flags) != protection_flags) {
+		return 0;
+	}
+
+        __do_tlb_refill(address, textaccess, pte);
+
+	return 1;
+}
+
+static int handle_tlbmiss(struct mm_struct *mm, unsigned long long protection_flags,
+			unsigned long long textaccess,
+			unsigned long address)
+{	
+	pgd_t *dir;
+	pmd_t *pmd;
+	pte_t *pte;
+	pte_t entry;
+	
+
+	/* NB. The PGD currently only contains a single entry - there is no
+	   page table tree stored for the top half of the address space since
+	   virtual pages in that region should never be mapped in user mode.
+	   (In kernel mode, the only things in that region are the 512Mb super
+	   page (locked in), and vmalloc (modules) +  I/O device pages (handled
+	   by handle_vmalloc_fault), so no PGD for the upper half is required
+	   by kernel mode either).
+
+	   See how mm->pgd is allocated and initialised in pgd_alloc to see why
+	   the next test is necessary.  - RPC */
+	if (address >= (unsigned long) TASK_SIZE) {
+		/* upper half - never has page table entries. */
+		return 0;
+	}
+	dir = pgd_offset(mm, address);
+	if (pgd_none(*dir)) {
+		return 0;
+	}
+	if (!pgd_present(*dir)) {
+		return 0;
+	}
+
+	pmd = pmd_offset(dir, address);
+	if (pmd_none(*pmd)) {
+		return 0;
+	}
+	if (!pmd_present(*pmd)) {
+		return 0;
+	}
+	pte = pte_offset(pmd, address);
+	entry = *pte;
+	if (pte_none(entry)) {
+		return 0;
+	}
+	if (!pte_present(entry)) {
+		return 0;
+	}
+
+	/* If the page doesn't have sufficient protection bits set to service the
+	   kind of fault being handled, there's not much point doing the TLB refill.
+	   Punt the fault to the general handler. */
+	if ((pte_val(entry) & protection_flags) != protection_flags) {
+		return 0;
+	}
+
+        __do_tlb_refill(address, textaccess, pte);
+
+	return 1;
+}
+
+/* Put all this information into one structure so that everything is just arithmetic
+   relative to a single base address.  This reduces the number of movi/shori pairs needed
+   just to load addresses of static data. */
+struct expevt_lookup {
+	unsigned short protection_flags[8];
+	unsigned char  is_text_access[8];
+	unsigned char  is_write_access[8];
+};
+
+#define PRU (1<<9)
+#define PRW (1<<8)
+#define PRX (1<<7)
+#define PRR (1<<6)
+
+#define DIRTY (_PAGE_DIRTY | _PAGE_ACCESSED)
+#define YOUNG (_PAGE_ACCESSED)
+
+/* Sized as 8 rather than 4 to allow checking the PTE's PRU bit against whether
+   the fault happened in user mode or privileged mode. */
+static struct expevt_lookup expevt_lookup_table = {
+	.protection_flags = {PRX, PRX, 0, 0, PRR, PRR, PRW, PRW},
+	.is_text_access   = {1,   1,   0, 0, 0,   0,   0,   0}
+};
+
+/*
+   This routine handles page faults that can be serviced just by refilling a
+   TLB entry from an existing page table entry.  (This case represents a very
+   large majority of page faults.) Return 1 if the fault was successfully
+   handled.  Return 0 if the fault could not be handled.  (This leads into the
+   general fault handling in fault.c which deals with mapping file-backed
+   pages, stack growth, segmentation faults, swapping etc etc)
+ */
+asmlinkage int do_fast_page_fault(unsigned long long ssr_md, unsigned long long expevt,
+			          unsigned long address)
+{
+	struct task_struct *tsk;
+	struct mm_struct *mm;
+	unsigned long long textaccess;
+	unsigned long long protection_flags;
+	unsigned long long index;
+	unsigned long long expevt4;
+
+	/* The next few lines implement a way of hashing EXPEVT into a small array index
+	   which can be used to lookup parameters specific to the type of TLBMISS being
+	   handled.  Note:
+	   ITLBMISS has EXPEVT==0xa40
+	   RTLBMISS has EXPEVT==0x040
+	   WTLBMISS has EXPEVT==0x060
+	*/
+
+	expevt4 = (expevt >> 4);
+	/* TODO : xor ssr_md into this expression too.  Then we can check that PRU is set
+	   when it needs to be. */
+	index = expevt4 ^ (expevt4 >> 5);
+	index &= 7;
+	protection_flags = expevt_lookup_table.protection_flags[index];
+	textaccess       = expevt_lookup_table.is_text_access[index];
+
+#if (CONFIG_SH64_PROC_TLB)
+	++calls_to_do_fast_page_fault;
+#endif
+
+	/* SIM
+	 * Note this is now called with interrupts still disabled
+	 * This is to cope with being called for a missing IO port
+	 * address with interupts disabled. This should be fixed as
+	 * soon as we have a better 'fast path' miss handler.
+	 *
+	 * Plus take care how you try and debug this stuff.
+	 * For example, writing debug data to a port which you
+	 * have just faulted on is not going to work.
+	 */
+
+	tsk = current;
+	mm = tsk->mm;
+
+	if ((address >= VMALLOC_START && address < VMALLOC_END) ||
+	    (address >= IOBASE_VADDR  && address < IOBASE_END)) {
+		if (ssr_md) {
+			/* Process-contexts can never have this address range mapped */
+			if (handle_vmalloc_fault(mm, protection_flags, textaccess, address)) {
+				return 1;
+			}
+		}
+	} else if (!in_interrupt() && mm) {
+		if (handle_tlbmiss(mm, protection_flags, textaccess, address)) {
+			return 1;
+		}
+	}
+
+	return 0;
+
+}
+