[Blackfin] arch: Initial checkin of the memory protection support.

Enable it with CONFIG_MPU.

Signed-off-by: Bernd Schmidt <bernd.schmidt@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

1 files changed, 338 insertions, 0 deletions

diff --git a/arch/blackfin/kernel/cplb-mpu/cplbmgr.c b/arch/blackfin/kernel/cplb-mpu/cplbmgr.c
new file mode 100644
index 000000000000..c426a22f9907
--- /dev/null
+++ b/arch/blackfin/kernel/cplb-mpu/cplbmgr.c
@@ -0,0 +1,338 @@
+/*
+ *               Blackfin CPLB exception handling.
+ *               Copyright 2004-2007 Analog Devices Inc.
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include <linux/module.h>
+#include <linux/mm.h>
+
+#include <asm/blackfin.h>
+#include <asm/cplbinit.h>
+#include <asm/mmu_context.h>
+
+#ifdef CONFIG_BFIN_ICACHE
+
+#define FAULT_RW        (1 << 16)
+#define FAULT_USERSUPV  (1 << 17)
+
+int page_mask_nelts;
+int page_mask_order;
+unsigned long *current_rwx_mask;
+
+int nr_dcplb_miss, nr_icplb_miss, nr_icplb_supv_miss, nr_dcplb_prot;
+int nr_cplb_flush;
+
+static inline void disable_dcplb(void)
+{
+        unsigned long ctrl;
+        SSYNC();
+        ctrl = bfin_read_DMEM_CONTROL();
+        ctrl &= ~ENDCPLB;
+        bfin_write_DMEM_CONTROL(ctrl);
+        SSYNC();
+}
+
+static inline void enable_dcplb(void)
+{
+        unsigned long ctrl;
+        SSYNC();
+        ctrl = bfin_read_DMEM_CONTROL();
+        ctrl |= ENDCPLB;
+        bfin_write_DMEM_CONTROL(ctrl);
+        SSYNC();
+}
+
+static inline void disable_icplb(void)
+{
+        unsigned long ctrl;
+        SSYNC();
+        ctrl = bfin_read_IMEM_CONTROL();
+        ctrl &= ~ENICPLB;
+        bfin_write_IMEM_CONTROL(ctrl);
+        SSYNC();
+}
+
+static inline void enable_icplb(void)
+{
+        unsigned long ctrl;
+        SSYNC();
+        ctrl = bfin_read_IMEM_CONTROL();
+        ctrl |= ENICPLB;
+        bfin_write_IMEM_CONTROL(ctrl);
+        SSYNC();
+}
+
+/*
+ * Given the contents of the status register, return the index of the
+ * CPLB that caused the fault.
+ */
+static inline int faulting_cplb_index(int status)
+{
+        int signbits = __builtin_bfin_norm_fr1x32(status & 0xFFFF);
+        return 30 - signbits;
+}
+
+/*
+ * Given the contents of the status register and the DCPLB_DATA contents,
+ * return true if a write access should be permitted.
+ */
+static inline int write_permitted(int status, unsigned long data)
+{
+        if (status & FAULT_USERSUPV)
+                return !!(data & CPLB_SUPV_WR);
+        else
+                return !!(data & CPLB_USER_WR);
+}
+
+/* Counters to implement round-robin replacement.  */
+static int icplb_rr_index, dcplb_rr_index;
+
+/*
+ * Find an ICPLB entry to be evicted and return its index.
+ */
+static int evict_one_icplb(void)
+{
+        int i;
+        for (i = first_switched_icplb; i < MAX_CPLBS; i++)
+                if ((icplb_tbl[i].data & CPLB_VALID) == 0)
+                        return i;
+        i = first_switched_icplb + icplb_rr_index;
+        if (i >= MAX_CPLBS) {
+                i -= MAX_CPLBS - first_switched_icplb;
+                icplb_rr_index -= MAX_CPLBS - first_switched_icplb;
+        }
+        icplb_rr_index++;
+        return i;
+}
+
+static int evict_one_dcplb(void)
+{
+        int i;
+        for (i = first_switched_dcplb; i < MAX_CPLBS; i++)
+                if ((dcplb_tbl[i].data & CPLB_VALID) == 0)
+                        return i;
+        i = first_switched_dcplb + dcplb_rr_index;
+        if (i >= MAX_CPLBS) {
+                i -= MAX_CPLBS - first_switched_dcplb;
+                dcplb_rr_index -= MAX_CPLBS - first_switched_dcplb;
+        }
+        dcplb_rr_index++;
+        return i;
+}
+
+static noinline int dcplb_miss(void)
+{
+        unsigned long addr = bfin_read_DCPLB_FAULT_ADDR();
+        int status = bfin_read_DCPLB_STATUS();
+        unsigned long *mask;
+        int idx;
+        unsigned long d_data;
+
+        nr_dcplb_miss++;
+        if (addr >= _ramend)
+                return CPLB_PROT_VIOL;
+
+        d_data = CPLB_SUPV_WR | CPLB_VALID | CPLB_DIRTY | PAGE_SIZE_4KB;
+#ifdef CONFIG_BFIN_DCACHE
+        d_data |= CPLB_L1_CHBL | ANOMALY_05000158_WORKAROUND;
+#ifdef CONFIG_BLKFIN_WT
+        d_data |= CPLB_L1_AOW | CPLB_WT;
+#endif
+#endif
+        mask = current_rwx_mask;
+        if (mask) {
+                int page = addr >> PAGE_SHIFT;
+                int offs = page >> 5;
+                int bit = 1 << (page & 31);
+
+                if (mask[offs] & bit)
+                        d_data |= CPLB_USER_RD;
+
+                mask += page_mask_nelts;
+                if (mask[offs] & bit)
+                        d_data |= CPLB_USER_WR;
+        }
+
+        idx = evict_one_dcplb();
+
+        addr &= PAGE_MASK;
+        dcplb_tbl[idx].addr = addr;
+        dcplb_tbl[idx].data = d_data;
+
+        disable_dcplb();
+        bfin_write32(DCPLB_DATA0 + idx * 4, d_data);
+        bfin_write32(DCPLB_ADDR0 + idx * 4, addr);
+        enable_dcplb();
+
+        return 0;
+}
+
+static noinline int icplb_miss(void)
+{
+        unsigned long addr = bfin_read_ICPLB_FAULT_ADDR();
+        int status = bfin_read_ICPLB_STATUS();
+        int idx;
+        unsigned long i_data;
+
+        nr_icplb_miss++;
+        if (status & FAULT_USERSUPV)
+                nr_icplb_supv_miss++;
+
+        if (addr >= _ramend)
+                return CPLB_PROT_VIOL;
+
+        /*
+         * First, try to find a CPLB that matches this address.  If we
+         * find one, then the fact that we're in the miss handler means
+         * that the instruction crosses a page boundary.
+         */
+        for (idx = first_switched_icplb; idx < MAX_CPLBS; idx++) {
+                if (icplb_tbl[idx].data & CPLB_VALID) {
+                        unsigned long this_addr = icplb_tbl[idx].addr;
+                        if (this_addr <= addr && this_addr + PAGE_SIZE > addr) {
+                                addr += PAGE_SIZE;
+                                break;
+                        }
+                }
+        }
+
+        i_data = CPLB_VALID | CPLB_PORTPRIO | PAGE_SIZE_4KB;
+#ifdef CONFIG_BFIN_ICACHE
+        i_data |= CPLB_L1_CHBL | ANOMALY_05000158_WORKAROUND;
+#endif
+
+        /*
+         * Two cases to distinguish - a supervisor access must necessarily
+         * be for a module page; we grant it unconditionally (could do better
+         * here in the future).  Otherwise, check the x bitmap of the current
+         * process.
+         */
+        if (!(status & FAULT_USERSUPV)) {
+                unsigned long *mask = current_rwx_mask;
+
+                if (mask) {
+                        int page = addr >> PAGE_SHIFT;
+                        int offs = page >> 5;
+                        int bit = 1 << (page & 31);
+
+                        mask += 2 * page_mask_nelts;
+                        if (mask[offs] & bit)
+                                i_data |= CPLB_USER_RD;
+                }
+        }
+
+        idx = evict_one_icplb();
+        addr &= PAGE_MASK;
+        icplb_tbl[idx].addr = addr;
+        icplb_tbl[idx].data = i_data;
+
+        disable_icplb();
+        bfin_write32(ICPLB_DATA0 + idx * 4, i_data);
+        bfin_write32(ICPLB_ADDR0 + idx * 4, addr);
+        enable_icplb();
+
+        return 0;
+}
+
+static noinline int dcplb_protection_fault(void)
+{
+        unsigned long addr = bfin_read_DCPLB_FAULT_ADDR();
+        int status = bfin_read_DCPLB_STATUS();
+
+        nr_dcplb_prot++;
+
+        if (status & FAULT_RW) {
+                int idx = faulting_cplb_index(status);
+                unsigned long data = dcplb_tbl[idx].data;
+                if (!(data & CPLB_WT) && !(data & CPLB_DIRTY) &&
+                    write_permitted(status, data)) {
+                        data |= CPLB_DIRTY;
+                        dcplb_tbl[idx].data = data;
+                        bfin_write32(DCPLB_DATA0 + idx * 4, data);
+                        return 0;
+                }
+        }
+        return CPLB_PROT_VIOL;
+}
+
+int cplb_hdr(int seqstat, struct pt_regs *regs)
+{
+        int cause = seqstat & 0x3f;
+        switch (cause) {
+        case 0x23:
+                return dcplb_protection_fault();
+        case 0x2C:
+                return icplb_miss();
+        case 0x26:
+                return dcplb_miss();
+        default:
+            return 1;
+                panic_cplb_error(seqstat, regs);
+        }
+}
+
+void flush_switched_cplbs(void)
+{
+        int i;
+
+        nr_cplb_flush++;
+
+        disable_icplb();
+        for (i = first_switched_icplb; i < MAX_CPLBS; i++) {
+                icplb_tbl[i].data = 0;
+                bfin_write32(ICPLB_DATA0 + i * 4, 0);
+        }
+        enable_icplb();
+
+        disable_dcplb();
+        for (i = first_mask_dcplb; i < MAX_CPLBS; i++) {
+                dcplb_tbl[i].data = 0;
+                bfin_write32(DCPLB_DATA0 + i * 4, 0);
+        }
+        enable_dcplb();
+}
+
+void set_mask_dcplbs(unsigned long *masks)
+{
+        int i;
+        unsigned long addr = (unsigned long)masks;
+        unsigned long d_data;
+        current_rwx_mask = masks;
+
+        if (!masks)
+                return;
+
+        d_data = CPLB_SUPV_WR | CPLB_VALID | CPLB_DIRTY | PAGE_SIZE_4KB;
+#ifdef CONFIG_BFIN_DCACHE
+        d_data |= CPLB_L1_CHBL;
+#ifdef CONFIG_BLKFIN_WT
+        d_data |= CPLB_L1_AOW | CPLB_WT;
+#endif
+#endif
+
+        disable_dcplb();
+        for (i = first_mask_dcplb; i < first_switched_dcplb; i++) {
+                dcplb_tbl[i].addr = addr;
+                dcplb_tbl[i].data = d_data;
+                bfin_write32(DCPLB_DATA0 + i * 4, d_data);
+                bfin_write32(DCPLB_ADDR0 + i * 4, addr);
+                addr += PAGE_SIZE;
+        }
+        enable_dcplb();
+}
+
+#endif