Initial import

1 files changed, 166 insertions, 0 deletions

diff --git a/arch/sh/mm/tlbex_64.c b/arch/sh/mm/tlbex_64.c
new file mode 100644
index 000000000..8557548fc
--- /dev/null
+++ b/arch/sh/mm/tlbex_64.c
@@ -0,0 +1,166 @@
+/*
+ * The SH64 TLB miss.
+ *
+ * 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 registers 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.
+ *
+ * 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.
+ */
+#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/interrupt.h>
+#include <linux/kprobes.h>
+#include <asm/tlb.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/pgalloc.h>
+#include <asm/mmu_context.h>
+
+static int handle_tlbmiss(unsigned long long protection_flags,
+			  unsigned long address)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	pte_t entry;
+
+	if (is_vmalloc_addr((void *)address)) {
+		pgd = pgd_offset_k(address);
+	} else {
+		if (unlikely(address >= TASK_SIZE || !current->mm))
+			return 1;
+
+		pgd = pgd_offset(current->mm, address);
+	}
+
+	pud = pud_offset(pgd, address);
+	if (pud_none(*pud) || !pud_present(*pud))
+		return 1;
+
+	pmd = pmd_offset(pud, address);
+	if (pmd_none(*pmd) || !pmd_present(*pmd))
+		return 1;
+
+	pte = pte_offset_kernel(pmd, address);
+	entry = *pte;
+	if (pte_none(entry) || !pte_present(entry))
+		return 1;
+
+	/*
+	 * 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 1;
+
+	update_mmu_cache(NULL, address, pte);
+
+	return 0;
+}
+
+/*
+ * 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)
+
+/* 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}
+};
+
+static inline unsigned int
+expevt_to_fault_code(unsigned long expevt)
+{
+	if (expevt == 0xa40)
+		return FAULT_CODE_ITLB;
+	else if (expevt == 0x060)
+		return FAULT_CODE_WRITE;
+
+	return 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 __kprobes
+do_fast_page_fault(unsigned long long ssr_md, unsigned long long expevt,
+		   unsigned long address)
+{
+	unsigned long long protection_flags;
+	unsigned long long index;
+	unsigned long long expevt4;
+	unsigned int fault_code;
+
+	/* 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;
+
+	fault_code = expevt_to_fault_code(expevt);
+
+	protection_flags = expevt_lookup_table.protection_flags[index];
+
+	if (expevt_lookup_table.is_text_access[index])
+		fault_code |= FAULT_CODE_ITLB;
+	if (!ssr_md)
+		fault_code |= FAULT_CODE_USER;
+
+	set_thread_fault_code(fault_code);
+
+	return handle_tlbmiss(protection_flags, address);
+}