/**
|
* 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);
|
