3 files changed, 792 insertions, 0 deletions

diff --git a/arch/x86/platform/intel-quark/Makefile b/arch/x86/platform/intel-quark/Makefile
new file mode 100644
index 000000000000..9cc57ed36022
--- /dev/null
+++ b/arch/x86/platform/intel-quark/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_INTEL_IMR) += imr.o
+obj-$(CONFIG_DEBUG_IMR_SELFTEST) += imr_selftest.o
diff --git a/arch/x86/platform/intel-quark/imr.c b/arch/x86/platform/intel-quark/imr.c
new file mode 100644
index 000000000000..0ee619f9fcb7
--- /dev/null
+++ b/arch/x86/platform/intel-quark/imr.c
@@ -0,0 +1,661 @@
+/**
+ * imr.c
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2015 Bryan O'Donoghue <pure.logic@nexus-software.ie>
+ *
+ * IMR registers define an isolated region of memory that can
+ * be masked to prohibit certain system agents from accessing memory.
+ * When a device behind a masked port performs an access - snooped or
+ * not, an IMR may optionally prevent that transaction from changing
+ * the state of memory or from getting correct data in response to the
+ * operation.
+ *
+ * Write data will be dropped and reads will return 0xFFFFFFFF, the
+ * system will reset and system BIOS will print out an error message to
+ * inform the user that an IMR has been violated.
+ *
+ * This code is based on the Linux MTRR code and reference code from
+ * Intel's Quark BSP EFI, Linux and grub code.
+ *
+ * See quark-x1000-datasheet.pdf for register definitions.
+ * http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/quark-x1000-datasheet.pdf
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <asm-generic/sections.h>
+#include <asm/cpu_device_id.h>
+#include <asm/imr.h>
+#include <asm/iosf_mbi.h>
+#include <linux/debugfs.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+struct imr_device {
+        struct dentry   *file;
+        bool            init;
+        struct mutex    lock;
+        int             max_imr;
+        int             reg_base;
+};
+
+static struct imr_device imr_dev;
+
+/*
+ * IMR read/write mask control registers.
+ * See quark-x1000-datasheet.pdf sections 12.7.4.5 and 12.7.4.6 for
+ * bit definitions.
+ *
+ * addr_hi
+ * 31           Lock bit
+ * 30:24        Reserved
+ * 23:2         1 KiB aligned lo address
+ * 1:0          Reserved
+ *
+ * addr_hi
+ * 31:24        Reserved
+ * 23:2         1 KiB aligned hi address
+ * 1:0          Reserved
+ */
+#define IMR_LOCK        BIT(31)
+
+struct imr_regs {
+        u32 addr_lo;
+        u32 addr_hi;
+        u32 rmask;
+        u32 wmask;
+};
+
+#define IMR_NUM_REGS    (sizeof(struct imr_regs)/sizeof(u32))
+#define IMR_SHIFT       8
+#define imr_to_phys(x)  ((x) << IMR_SHIFT)
+#define phys_to_imr(x)  ((x) >> IMR_SHIFT)
+
+/**
+ * imr_is_enabled - true if an IMR is enabled false otherwise.
+ *
+ * Determines if an IMR is enabled based on address range and read/write
+ * mask. An IMR set with an address range set to zero and a read/write
+ * access mask set to all is considered to be disabled. An IMR in any
+ * other state - for example set to zero but without read/write access
+ * all is considered to be enabled. This definition of disabled is how
+ * firmware switches off an IMR and is maintained in kernel for
+ * consistency.
+ *
+ * @imr:        pointer to IMR descriptor.
+ * @return:     true if IMR enabled false if disabled.
+ */
+static inline int imr_is_enabled(struct imr_regs *imr)
+{
+        return !(imr->rmask == IMR_READ_ACCESS_ALL &&
+                 imr->wmask == IMR_WRITE_ACCESS_ALL &&
+                 imr_to_phys(imr->addr_lo) == 0 &&
+                 imr_to_phys(imr->addr_hi) == 0);
+}
+
+/**
+ * imr_read - read an IMR at a given index.
+ *
+ * Requires caller to hold imr mutex.
+ *
+ * @idev:       pointer to imr_device structure.
+ * @imr_id:     IMR entry to read.
+ * @imr:        IMR structure representing address and access masks.
+ * @return:     0 on success or error code passed from mbi_iosf on failure.
+ */
+static int imr_read(struct imr_device *idev, u32 imr_id, struct imr_regs *imr)
+{
+        u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base;
+        int ret;
+
+        ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+                                reg++, &imr->addr_lo);
+        if (ret)
+                return ret;
+
+        ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+                                reg++, &imr->addr_hi);
+        if (ret)
+                return ret;
+
+        ret = iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+                                reg++, &imr->rmask);
+        if (ret)
+                return ret;
+
+        return iosf_mbi_read(QRK_MBI_UNIT_MM, QRK_MBI_MM_READ,
+                                reg++, &imr->wmask);
+}
+
+/**
+ * imr_write - write an IMR at a given index.
+ *
+ * Requires caller to hold imr mutex.
+ * Note lock bits need to be written independently of address bits.
+ *
+ * @idev:       pointer to imr_device structure.
+ * @imr_id:     IMR entry to write.
+ * @imr:        IMR structure representing address and access masks.
+ * @lock:       indicates if the IMR lock bit should be applied.
+ * @return:     0 on success or error code passed from mbi_iosf on failure.
+ */
+static int imr_write(struct imr_device *idev, u32 imr_id,
+                     struct imr_regs *imr, bool lock)
+{
+        unsigned long flags;
+        u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base;
+        int ret;
+
+        local_irq_save(flags);
+
+        ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE, reg++,
+                                imr->addr_lo);
+        if (ret)
+                goto failed;
+
+        ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+                                reg++, imr->addr_hi);
+        if (ret)
+                goto failed;
+
+        ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+                                reg++, imr->rmask);
+        if (ret)
+                goto failed;
+
+        ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+                                reg++, imr->wmask);
+        if (ret)
+                goto failed;
+
+        /* Lock bit must be set separately to addr_lo address bits. */
+        if (lock) {
+                imr->addr_lo |= IMR_LOCK;
+                ret = iosf_mbi_write(QRK_MBI_UNIT_MM, QRK_MBI_MM_WRITE,
+                                        reg - IMR_NUM_REGS, imr->addr_lo);
+                if (ret)
+                        goto failed;
+        }
+
+        local_irq_restore(flags);
+        return 0;
+failed:
+        /*
+         * If writing to the IOSF failed then we're in an unknown state,
+         * likely a very bad state. An IMR in an invalid state will almost
+         * certainly lead to a memory access violation.
+         */
+        local_irq_restore(flags);
+        WARN(ret, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",
+             imr_to_phys(imr->addr_lo), imr_to_phys(imr->addr_hi) + IMR_MASK);
+
+        return ret;
+}
+
+/**
+ * imr_dbgfs_state_show - print state of IMR registers.
+ *
+ * @s:          pointer to seq_file for output.
+ * @unused:     unused parameter.
+ * @return:     0 on success or error code passed from mbi_iosf on failure.
+ */
+static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
+{
+        phys_addr_t base;
+        phys_addr_t end;
+        int i;
+        struct imr_device *idev = s->private;
+        struct imr_regs imr;
+        size_t size;
+        int ret = -ENODEV;
+
+        mutex_lock(&idev->lock);
+
+        for (i = 0; i < idev->max_imr; i++) {
+
+                ret = imr_read(idev, i, &imr);
+                if (ret)
+                        break;
+
+                /*
+                 * Remember to add IMR_ALIGN bytes to size to indicate the
+                 * inherent IMR_ALIGN size bytes contained in the masked away
+                 * lower ten bits.
+                 */
+                if (imr_is_enabled(&imr)) {
+                        base = imr_to_phys(imr.addr_lo);
+                        end = imr_to_phys(imr.addr_hi) + IMR_MASK;
+                } else {
+                        base = 0;
+                        end = 0;
+                }
+                size = end - base;
+                seq_printf(s, "imr%02i: base=%pa, end=%pa, size=0x%08zx "
+                           "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
+                           &base, &end, size, imr.rmask, imr.wmask,
+                           imr_is_enabled(&imr) ? "enabled " : "disabled",
+                           imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
+        }
+
+        mutex_unlock(&idev->lock);
+        return ret;
+}
+
+/**
+ * imr_state_open - debugfs open callback.
+ *
+ * @inode:      pointer to struct inode.
+ * @file:       pointer to struct file.
+ * @return:     result of single open.
+ */
+static int imr_state_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, imr_dbgfs_state_show, inode->i_private);
+}
+
+static const struct file_operations imr_state_ops = {
+        .open           = imr_state_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+/**
+ * imr_debugfs_register - register debugfs hooks.
+ *
+ * @idev:       pointer to imr_device structure.
+ * @return:     0 on success - errno on failure.
+ */
+static int imr_debugfs_register(struct imr_device *idev)
+{
+        idev->file = debugfs_create_file("imr_state", S_IFREG | S_IRUGO, NULL,
+                                         idev, &imr_state_ops);
+        return PTR_ERR_OR_ZERO(idev->file);
+}
+
+/**
+ * imr_debugfs_unregister - unregister debugfs hooks.
+ *
+ * @idev:       pointer to imr_device structure.
+ * @return:
+ */
+static void imr_debugfs_unregister(struct imr_device *idev)
+{
+        debugfs_remove(idev->file);
+}
+
+/**
+ * imr_check_params - check passed address range IMR alignment and non-zero size
+ *
+ * @base:       base address of intended IMR.
+ * @size:       size of intended IMR.
+ * @return:     zero on valid range -EINVAL on unaligned base/size.
+ */
+static int imr_check_params(phys_addr_t base, size_t size)
+{
+        if ((base & IMR_MASK) || (size & IMR_MASK)) {
+                pr_err("base %pa size 0x%08zx must align to 1KiB\n",
+                        &base, size);
+                return -EINVAL;
+        }
+        if (size == 0)
+                return -EINVAL;
+
+        return 0;
+}
+
+/**
+ * imr_raw_size - account for the IMR_ALIGN bytes that addr_hi appends.
+ *
+ * IMR addr_hi has a built in offset of plus IMR_ALIGN (0x400) bytes from the
+ * value in the register. We need to subtract IMR_ALIGN bytes from input sizes
+ * as a result.
+ *
+ * @size:       input size bytes.
+ * @return:     reduced size.
+ */
+static inline size_t imr_raw_size(size_t size)
+{
+        return size - IMR_ALIGN;
+}
+
+/**
+ * imr_address_overlap - detects an address overlap.
+ *
+ * @addr:       address to check against an existing IMR.
+ * @imr:        imr being checked.
+ * @return:     true for overlap false for no overlap.
+ */
+static inline int imr_address_overlap(phys_addr_t addr, struct imr_regs *imr)
+{
+        return addr >= imr_to_phys(imr->addr_lo) && addr <= imr_to_phys(imr->addr_hi);
+}
+
+/**
+ * imr_add_range - add an Isolated Memory Region.
+ *
+ * @base:       physical base address of region aligned to 1KiB.
+ * @size:       physical size of region in bytes must be aligned to 1KiB.
+ * @read_mask:  read access mask.
+ * @write_mask: write access mask.
+ * @lock:       indicates whether or not to permanently lock this region.
+ * @return:     zero on success or negative value indicating error.
+ */
+int imr_add_range(phys_addr_t base, size_t size,
+                  unsigned int rmask, unsigned int wmask, bool lock)
+{
+        phys_addr_t end;
+        unsigned int i;
+        struct imr_device *idev = &imr_dev;
+        struct imr_regs imr;
+        size_t raw_size;
+        int reg;
+        int ret;
+
+        if (WARN_ONCE(idev->init == false, "driver not initialized"))
+                return -ENODEV;
+
+        ret = imr_check_params(base, size);
+        if (ret)
+                return ret;
+
+        /* Tweak the size value. */
+        raw_size = imr_raw_size(size);
+        end = base + raw_size;
+
+        /*
+         * Check for reserved IMR value common to firmware, kernel and grub
+         * indicating a disabled IMR.
+         */
+        imr.addr_lo = phys_to_imr(base);
+        imr.addr_hi = phys_to_imr(end);
+        imr.rmask = rmask;
+        imr.wmask = wmask;
+        if (!imr_is_enabled(&imr))
+                return -ENOTSUPP;
+
+        mutex_lock(&idev->lock);
+
+        /*
+         * Find a free IMR while checking for an existing overlapping range.
+         * Note there's no restriction in silicon to prevent IMR overlaps.
+         * For the sake of simplicity and ease in defining/debugging an IMR
+         * memory map we exclude IMR overlaps.
+         */
+        reg = -1;
+        for (i = 0; i < idev->max_imr; i++) {
+                ret = imr_read(idev, i, &imr);
+                if (ret)
+                        goto failed;
+
+                /* Find overlap @ base or end of requested range. */
+                ret = -EINVAL;
+                if (imr_is_enabled(&imr)) {
+                        if (imr_address_overlap(base, &imr))
+                                goto failed;
+                        if (imr_address_overlap(end, &imr))
+                                goto failed;
+                } else {
+                        reg = i;
+                }
+        }
+
+        /* Error out if we have no free IMR entries. */
+        if (reg == -1) {
+                ret = -ENOMEM;
+                goto failed;
+        }
+
+        pr_debug("add %d phys %pa-%pa size %zx mask 0x%08x wmask 0x%08x\n",
+                 reg, &base, &end, raw_size, rmask, wmask);
+
+        /* Enable IMR at specified range and access mask. */
+        imr.addr_lo = phys_to_imr(base);
+        imr.addr_hi = phys_to_imr(end);
+        imr.rmask = rmask;
+        imr.wmask = wmask;
+
+        ret = imr_write(idev, reg, &imr, lock);
+        if (ret < 0) {
+                /*
+                 * In the highly unlikely event iosf_mbi_write failed
+                 * attempt to rollback the IMR setup skipping the trapping
+                 * of further IOSF write failures.
+                 */
+                imr.addr_lo = 0;
+                imr.addr_hi = 0;
+                imr.rmask = IMR_READ_ACCESS_ALL;
+                imr.wmask = IMR_WRITE_ACCESS_ALL;
+                imr_write(idev, reg, &imr, false);
+        }
+failed:
+        mutex_unlock(&idev->lock);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(imr_add_range);
+
+/**
+ * __imr_remove_range - delete an Isolated Memory Region.
+ *
+ * This function allows you to delete an IMR by its index specified by reg or
+ * by address range specified by base and size respectively. If you specify an
+ * index on its own the base and size parameters are ignored.
+ * imr_remove_range(0, base, size); delete IMR at index 0 base/size ignored.
+ * imr_remove_range(-1, base, size); delete IMR from base to base+size.
+ *
+ * @reg:        imr index to remove.
+ * @base:       physical base address of region aligned to 1 KiB.
+ * @size:       physical size of region in bytes aligned to 1 KiB.
+ * @return:     -EINVAL on invalid range or out or range id
+ *              -ENODEV if reg is valid but no IMR exists or is locked
+ *              0 on success.
+ */
+static int __imr_remove_range(int reg, phys_addr_t base, size_t size)
+{
+        phys_addr_t end;
+        bool found = false;
+        unsigned int i;
+        struct imr_device *idev = &imr_dev;
+        struct imr_regs imr;
+        size_t raw_size;
+        int ret = 0;
+
+        if (WARN_ONCE(idev->init == false, "driver not initialized"))
+                return -ENODEV;
+
+        /*
+         * Validate address range if deleting by address, else we are
+         * deleting by index where base and size will be ignored.
+         */
+        if (reg == -1) {
+                ret = imr_check_params(base, size);
+                if (ret)
+                        return ret;
+        }
+
+        /* Tweak the size value. */
+        raw_size = imr_raw_size(size);
+        end = base + raw_size;
+
+        mutex_lock(&idev->lock);
+
+        if (reg >= 0) {
+                /* If a specific IMR is given try to use it. */
+                ret = imr_read(idev, reg, &imr);
+                if (ret)
+                        goto failed;
+
+                if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
+                        ret = -ENODEV;
+                        goto failed;
+                }
+                found = true;
+        } else {
+                /* Search for match based on address range. */
+                for (i = 0; i < idev->max_imr; i++) {
+                        ret = imr_read(idev, i, &imr);
+                        if (ret)
+                                goto failed;
+
+                        if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK)
+                                continue;
+
+                        if ((imr_to_phys(imr.addr_lo) == base) &&
+                            (imr_to_phys(imr.addr_hi) == end)) {
+                                found = true;
+                                reg = i;
+                                break;
+                        }
+                }
+        }
+
+        if (!found) {
+                ret = -ENODEV;
+                goto failed;
+        }
+
+        pr_debug("remove %d phys %pa-%pa size %zx\n", reg, &base, &end, raw_size);
+
+        /* Tear down the IMR. */
+        imr.addr_lo = 0;
+        imr.addr_hi = 0;
+        imr.rmask = IMR_READ_ACCESS_ALL;
+        imr.wmask = IMR_WRITE_ACCESS_ALL;
+
+        ret = imr_write(idev, reg, &imr, false);
+
+failed:
+        mutex_unlock(&idev->lock);
+        return ret;
+}
+
+/**
+ * imr_remove_range - delete an Isolated Memory Region by address
+ *
+ * This function allows you to delete an IMR by an address range specified
+ * by base and size respectively.
+ * imr_remove_range(base, size); delete IMR from base to base+size.
+ *
+ * @base:       physical base address of region aligned to 1 KiB.
+ * @size:       physical size of region in bytes aligned to 1 KiB.
+ * @return:     -EINVAL on invalid range or out or range id
+ *              -ENODEV if reg is valid but no IMR exists or is locked
+ *              0 on success.
+ */
+int imr_remove_range(phys_addr_t base, size_t size)
+{
+        return __imr_remove_range(-1, base, size);
+}
+EXPORT_SYMBOL_GPL(imr_remove_range);
+
+/**
+ * imr_clear - delete an Isolated Memory Region by index
+ *
+ * This function allows you to delete an IMR by an address range specified
+ * by the index of the IMR. Useful for initial sanitization of the IMR
+ * address map.
+ * imr_ge(base, size); delete IMR from base to base+size.
+ *
+ * @reg:        imr index to remove.
+ * @return:     -EINVAL on invalid range or out or range id
+ *              -ENODEV if reg is valid but no IMR exists or is locked
+ *              0 on success.
+ */
+static inline int imr_clear(int reg)
+{
+        return __imr_remove_range(reg, 0, 0);
+}
+
+/**
+ * imr_fixup_memmap - Tear down IMRs used during bootup.
+ *
+ * BIOS and Grub both setup IMRs around compressed kernel, initrd memory
+ * that need to be removed before the kernel hands out one of the IMR
+ * encased addresses to a downstream DMA agent such as the SD or Ethernet.
+ * IMRs on Galileo are setup to immediately reset the system on violation.
+ * As a result if you're running a root filesystem from SD - you'll need
+ * the boot-time IMRs torn down or you'll find seemingly random resets when
+ * using your filesystem.
+ *
+ * @idev:       pointer to imr_device structure.
+ * @return:
+ */
+static void __init imr_fixup_memmap(struct imr_device *idev)
+{
+        phys_addr_t base = virt_to_phys(&_text);
+        size_t size = virt_to_phys(&__end_rodata) - base;
+        int i;
+        int ret;
+
+        /* Tear down all existing unlocked IMRs. */
+        for (i = 0; i < idev->max_imr; i++)
+                imr_clear(i);
+
+        /*
+         * Setup a locked IMR around the physical extent of the kernel
+         * from the beginning of the .text secton to the end of the
+         * .rodata section as one physically contiguous block.
+         */
+        ret = imr_add_range(base, size, IMR_CPU, IMR_CPU, true);
+        if (ret < 0) {
+                pr_err("unable to setup IMR for kernel: (%p - %p)\n",
+                        &_text, &__end_rodata);
+        } else {
+                pr_info("protecting kernel .text - .rodata: %zu KiB (%p - %p)\n",
+                        size / 1024, &_text, &__end_rodata);
+        }
+
+}
+
+static const struct x86_cpu_id imr_ids[] __initconst = {
+        { X86_VENDOR_INTEL, 5, 9 },     /* Intel Quark SoC X1000. */
+        {}
+};
+MODULE_DEVICE_TABLE(x86cpu, imr_ids);
+
+/**
+ * imr_init - entry point for IMR driver.
+ *
+ * return: -ENODEV for no IMR support 0 if good to go.
+ */
+static int __init imr_init(void)
+{
+        struct imr_device *idev = &imr_dev;
+        int ret;
+
+        if (!x86_match_cpu(imr_ids) || !iosf_mbi_available())
+                return -ENODEV;
+
+        idev->max_imr = QUARK_X1000_IMR_MAX;
+        idev->reg_base = QUARK_X1000_IMR_REGBASE;
+        idev->init = true;
+
+        mutex_init(&idev->lock);
+        ret = imr_debugfs_register(idev);
+        if (ret != 0)
+                pr_warn("debugfs register failed!\n");
+        imr_fixup_memmap(idev);
+        return 0;
+}
+
+/**
+ * imr_exit - exit point for IMR code.
+ *
+ * Deregisters debugfs, leave IMR state as-is.
+ *
+ * return:
+ */
+static void __exit imr_exit(void)
+{
+        imr_debugfs_unregister(&imr_dev);
+}
+
+module_init(imr_init);
+module_exit(imr_exit);
+
+MODULE_AUTHOR("Bryan O'Donoghue <pure.logic@nexus-software.ie>");
+MODULE_DESCRIPTION("Intel Isolated Memory Region driver");
+MODULE_LICENSE("Dual BSD/GPL");
diff --git a/arch/x86/platform/intel-quark/imr_selftest.c b/arch/x86/platform/intel-quark/imr_selftest.c
new file mode 100644
index 000000000000..c9a0838890e2
--- /dev/null
+++ b/arch/x86/platform/intel-quark/imr_selftest.c
@@ -0,0 +1,129 @@
+/**
+ * imr_selftest.c
+ *
+ * Copyright(c) 2013 Intel Corporation.
+ * Copyright(c) 2015 Bryan O'Donoghue <pure.logic@nexus-software.ie>
+ *
+ * IMR self test. The purpose of this module is to run a set of tests on the
+ * IMR API to validate it's sanity. We check for overlapping, reserved
+ * addresses and setup/teardown sanity.
+ *
+ */
+
+#include <asm-generic/sections.h>
+#include <asm/imr.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#define SELFTEST KBUILD_MODNAME ": "
+/**
+ * imr_self_test_result - Print result string for self test.
+ *
+ * @res:        result code - true if test passed false otherwise.
+ * @fmt:        format string.
+ * ...          variadic argument list.
+ */
+static void __init imr_self_test_result(int res, const char *fmt, ...)
+{
+        va_list vlist;
+
+        /* Print pass/fail. */
+        if (res)
+                pr_info(SELFTEST "pass ");
+        else
+                pr_info(SELFTEST "fail ");
+
+        /* Print variable string. */
+        va_start(vlist, fmt);
+        vprintk(fmt, vlist);
+        va_end(vlist);
+
+        /* Optional warning. */
+        WARN(res == 0, "test failed");
+}
+#undef SELFTEST
+
+/**
+ * imr_self_test
+ *
+ * Verify IMR self_test with some simple tests to verify overlap,
+ * zero sized allocations and 1 KiB sized areas.
+ *
+ */
+static void __init imr_self_test(void)
+{
+        phys_addr_t base  = virt_to_phys(&_text);
+        size_t size = virt_to_phys(&__end_rodata) - base;
+        const char *fmt_over = "overlapped IMR @ (0x%08lx - 0x%08lx)\n";
+        int ret;
+
+        /* Test zero zero. */
+        ret = imr_add_range(0, 0, 0, 0, false);
+        imr_self_test_result(ret < 0, "zero sized IMR\n");
+
+        /* Test exact overlap. */
+        ret = imr_add_range(base, size, IMR_CPU, IMR_CPU, false);
+        imr_self_test_result(ret < 0, fmt_over, __va(base), __va(base + size));
+
+        /* Test overlap with base inside of existing. */
+        base += size - IMR_ALIGN;
+        ret = imr_add_range(base, size, IMR_CPU, IMR_CPU, false);
+        imr_self_test_result(ret < 0, fmt_over, __va(base), __va(base + size));
+
+        /* Test overlap with end inside of existing. */
+        base -= size + IMR_ALIGN * 2;
+        ret = imr_add_range(base, size, IMR_CPU, IMR_CPU, false);
+        imr_self_test_result(ret < 0, fmt_over, __va(base), __va(base + size));
+
+        /* Test that a 1 KiB IMR @ zero with read/write all will bomb out. */
+        ret = imr_add_range(0, IMR_ALIGN, IMR_READ_ACCESS_ALL,
+                            IMR_WRITE_ACCESS_ALL, false);
+        imr_self_test_result(ret < 0, "1KiB IMR @ 0x00000000 - access-all\n");
+
+        /* Test that a 1 KiB IMR @ zero with CPU only will work. */
+        ret = imr_add_range(0, IMR_ALIGN, IMR_CPU, IMR_CPU, false);
+        imr_self_test_result(ret >= 0, "1KiB IMR @ 0x00000000 - cpu-access\n");
+        if (ret >= 0) {
+                ret = imr_remove_range(0, IMR_ALIGN);
+                imr_self_test_result(ret == 0, "teardown - cpu-access\n");
+        }
+
+        /* Test 2 KiB works. */
+        size = IMR_ALIGN * 2;
+        ret = imr_add_range(0, size, IMR_READ_ACCESS_ALL,
+                            IMR_WRITE_ACCESS_ALL, false);
+        imr_self_test_result(ret >= 0, "2KiB IMR @ 0x00000000\n");
+        if (ret >= 0) {
+                ret = imr_remove_range(0, size);
+                imr_self_test_result(ret == 0, "teardown 2KiB\n");
+        }
+}
+
+/**
+ * imr_self_test_init - entry point for IMR driver.
+ *
+ * return: -ENODEV for no IMR support 0 if good to go.
+ */
+static int __init imr_self_test_init(void)
+{
+        imr_self_test();
+        return 0;
+}
+
+/**
+ * imr_self_test_exit - exit point for IMR code.
+ *
+ * return:
+ */
+static void __exit imr_self_test_exit(void)
+{
+}
+
+module_init(imr_self_test_init);
+module_exit(imr_self_test_exit);
+
+MODULE_AUTHOR("Bryan O'Donoghue <pure.logic@nexus-software.ie>");
+MODULE_DESCRIPTION("Intel Isolated Memory Region self-test driver");
+MODULE_LICENSE("Dual BSD/GPL");