1 files changed, 661 insertions, 0 deletions
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");