diff options
Diffstat (limited to 'arch/x86/platform/intel-quark/imr.c')
| -rw-r--r-- | arch/x86/platform/intel-quark/imr.c | 600 |
1 files changed, 600 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 000000000..49828c270 --- /dev/null +++ b/arch/x86/platform/intel-quark/imr.c @@ -0,0 +1,600 @@ +/** + * imr.c -- Intel Isolated Memory Region driver + * + * 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/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, MBI_REG_READ, reg++, &imr->addr_lo); + if (ret) + return ret; + + ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->addr_hi); + if (ret) + return ret; + + ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->rmask); + if (ret) + return ret; + + return iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_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. + * @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) +{ + 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, MBI_REG_WRITE, reg++, imr->addr_lo); + if (ret) + goto failed; + + ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->addr_hi); + if (ret) + goto failed; + + ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->rmask); + if (ret) + goto failed; + + ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->wmask); + 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; + size = end - base + 1; + } else { + base = 0; + end = 0; + size = 0; + } + 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; +} +DEFINE_SHOW_ATTRIBUTE(imr_dbgfs_state); + +/** + * 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", 0444, NULL, idev, + &imr_dbgfs_state_fops); + return PTR_ERR_OR_ZERO(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. + * @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) +{ + 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); + 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); + } +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); + +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; + unsigned long start, end; + int i; + int ret; + + /* Tear down all existing unlocked IMRs. */ + for (i = 0; i < idev->max_imr; i++) + imr_clear(i); + + start = (unsigned long)_text; + end = (unsigned long)__end_rodata - 1; + + /* + * Setup an unlocked 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. + * + * We don't round up @size since it is already PAGE_SIZE aligned. + * See vmlinux.lds.S for details. + */ + ret = imr_add_range(base, size, IMR_CPU, IMR_CPU); + if (ret < 0) { + pr_err("unable to setup IMR for kernel: %zu KiB (%lx - %lx)\n", + size / 1024, start, end); + } else { + pr_info("protecting kernel .text - .rodata: %zu KiB (%lx - %lx)\n", + size / 1024, start, end); + } + +} + +static const struct x86_cpu_id imr_ids[] __initconst = { + { X86_VENDOR_INTEL, 5, 9 }, /* Intel Quark SoC X1000. */ + {} +}; + +/** + * 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; +} +device_initcall(imr_init); |