diff options
Diffstat (limited to 'drivers/char/hw_random.c')
| -rw-r--r-- | drivers/char/hw_random.c | 630 |
1 files changed, 630 insertions, 0 deletions
diff --git a/drivers/char/hw_random.c b/drivers/char/hw_random.c new file mode 100644 index 00000000000..7e6ac14c245 --- /dev/null +++ b/drivers/char/hw_random.c @@ -0,0 +1,630 @@ +/* + Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG) + (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com> + + derived from + + Hardware driver for the AMD 768 Random Number Generator (RNG) + (c) Copyright 2001 Red Hat Inc <alan@redhat.com> + + derived from + + Hardware driver for Intel i810 Random Number Generator (RNG) + Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com> + Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com> + + Please read Documentation/hw_random.txt for details on use. + + ---------------------------------------------------------- + This software may be used and distributed according to the terms + of the GNU General Public License, incorporated herein by reference. + + */ + + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/pci.h> +#include <linux/interrupt.h> +#include <linux/spinlock.h> +#include <linux/random.h> +#include <linux/miscdevice.h> +#include <linux/smp_lock.h> +#include <linux/mm.h> +#include <linux/delay.h> + +#ifdef __i386__ +#include <asm/msr.h> +#include <asm/cpufeature.h> +#endif + +#include <asm/io.h> +#include <asm/uaccess.h> + + +/* + * core module and version information + */ +#define RNG_VERSION "1.0.0" +#define RNG_MODULE_NAME "hw_random" +#define RNG_DRIVER_NAME RNG_MODULE_NAME " hardware driver " RNG_VERSION +#define PFX RNG_MODULE_NAME ": " + + +/* + * debugging macros + */ + +/* pr_debug() collapses to a no-op if DEBUG is not defined */ +#define DPRINTK(fmt, args...) pr_debug(PFX "%s: " fmt, __FUNCTION__ , ## args) + + +#undef RNG_NDEBUG /* define to enable lightweight runtime checks */ +#ifdef RNG_NDEBUG +#define assert(expr) \ + if(!(expr)) { \ + printk(KERN_DEBUG PFX "Assertion failed! %s,%s,%s," \ + "line=%d\n", #expr, __FILE__, __FUNCTION__, __LINE__); \ + } +#else +#define assert(expr) +#endif + +#define RNG_MISCDEV_MINOR 183 /* official */ + +static int rng_dev_open (struct inode *inode, struct file *filp); +static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size, + loff_t * offp); + +static int __init intel_init (struct pci_dev *dev); +static void intel_cleanup(void); +static unsigned int intel_data_present (void); +static u32 intel_data_read (void); + +static int __init amd_init (struct pci_dev *dev); +static void amd_cleanup(void); +static unsigned int amd_data_present (void); +static u32 amd_data_read (void); + +#ifdef __i386__ +static int __init via_init(struct pci_dev *dev); +static void via_cleanup(void); +static unsigned int via_data_present (void); +static u32 via_data_read (void); +#endif + +struct rng_operations { + int (*init) (struct pci_dev *dev); + void (*cleanup) (void); + unsigned int (*data_present) (void); + u32 (*data_read) (void); + unsigned int n_bytes; /* number of bytes per ->data_read */ +}; +static struct rng_operations *rng_ops; + +static struct file_operations rng_chrdev_ops = { + .owner = THIS_MODULE, + .open = rng_dev_open, + .read = rng_dev_read, +}; + + +static struct miscdevice rng_miscdev = { + RNG_MISCDEV_MINOR, + RNG_MODULE_NAME, + &rng_chrdev_ops, +}; + +enum { + rng_hw_none, + rng_hw_intel, + rng_hw_amd, + rng_hw_via, +}; + +static struct rng_operations rng_vendor_ops[] = { + /* rng_hw_none */ + { }, + + /* rng_hw_intel */ + { intel_init, intel_cleanup, intel_data_present, + intel_data_read, 1 }, + + /* rng_hw_amd */ + { amd_init, amd_cleanup, amd_data_present, amd_data_read, 4 }, + +#ifdef __i386__ + /* rng_hw_via */ + { via_init, via_cleanup, via_data_present, via_data_read, 1 }, +#endif +}; + +/* + * Data for PCI driver interface + * + * This data only exists for exporting the supported + * PCI ids via MODULE_DEVICE_TABLE. We do not actually + * register a pci_driver, because someone else might one day + * want to register another driver on the same PCI id. + */ +static struct pci_device_id rng_pci_tbl[] = { + { 0x1022, 0x7443, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_amd }, + { 0x1022, 0x746b, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_amd }, + + { 0x8086, 0x2418, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel }, + { 0x8086, 0x2428, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel }, + { 0x8086, 0x2448, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel }, + { 0x8086, 0x244e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel }, + { 0x8086, 0x245e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, rng_hw_intel }, + + { 0, }, /* terminate list */ +}; +MODULE_DEVICE_TABLE (pci, rng_pci_tbl); + + +/*********************************************************************** + * + * Intel RNG operations + * + */ + +/* + * RNG registers (offsets from rng_mem) + */ +#define INTEL_RNG_HW_STATUS 0 +#define INTEL_RNG_PRESENT 0x40 +#define INTEL_RNG_ENABLED 0x01 +#define INTEL_RNG_STATUS 1 +#define INTEL_RNG_DATA_PRESENT 0x01 +#define INTEL_RNG_DATA 2 + +/* + * Magic address at which Intel PCI bridges locate the RNG + */ +#define INTEL_RNG_ADDR 0xFFBC015F +#define INTEL_RNG_ADDR_LEN 3 + +/* token to our ioremap'd RNG register area */ +static void __iomem *rng_mem; + +static inline u8 intel_hwstatus (void) +{ + assert (rng_mem != NULL); + return readb (rng_mem + INTEL_RNG_HW_STATUS); +} + +static inline u8 intel_hwstatus_set (u8 hw_status) +{ + assert (rng_mem != NULL); + writeb (hw_status, rng_mem + INTEL_RNG_HW_STATUS); + return intel_hwstatus (); +} + +static unsigned int intel_data_present(void) +{ + assert (rng_mem != NULL); + + return (readb (rng_mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT) ? + 1 : 0; +} + +static u32 intel_data_read(void) +{ + assert (rng_mem != NULL); + + return readb (rng_mem + INTEL_RNG_DATA); +} + +static int __init intel_init (struct pci_dev *dev) +{ + int rc; + u8 hw_status; + + DPRINTK ("ENTER\n"); + + rng_mem = ioremap (INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN); + if (rng_mem == NULL) { + printk (KERN_ERR PFX "cannot ioremap RNG Memory\n"); + rc = -EBUSY; + goto err_out; + } + + /* Check for Intel 82802 */ + hw_status = intel_hwstatus (); + if ((hw_status & INTEL_RNG_PRESENT) == 0) { + printk (KERN_ERR PFX "RNG not detected\n"); + rc = -ENODEV; + goto err_out_free_map; + } + + /* turn RNG h/w on, if it's off */ + if ((hw_status & INTEL_RNG_ENABLED) == 0) + hw_status = intel_hwstatus_set (hw_status | INTEL_RNG_ENABLED); + if ((hw_status & INTEL_RNG_ENABLED) == 0) { + printk (KERN_ERR PFX "cannot enable RNG, aborting\n"); + rc = -EIO; + goto err_out_free_map; + } + + DPRINTK ("EXIT, returning 0\n"); + return 0; + +err_out_free_map: + iounmap (rng_mem); + rng_mem = NULL; +err_out: + DPRINTK ("EXIT, returning %d\n", rc); + return rc; +} + +static void intel_cleanup(void) +{ + u8 hw_status; + + hw_status = intel_hwstatus (); + if (hw_status & INTEL_RNG_ENABLED) + intel_hwstatus_set (hw_status & ~INTEL_RNG_ENABLED); + else + printk(KERN_WARNING PFX "unusual: RNG already disabled\n"); + iounmap(rng_mem); + rng_mem = NULL; +} + +/*********************************************************************** + * + * AMD RNG operations + * + */ + +static u32 pmbase; /* PMxx I/O base */ +static struct pci_dev *amd_dev; + +static unsigned int amd_data_present (void) +{ + return inl(pmbase + 0xF4) & 1; +} + + +static u32 amd_data_read (void) +{ + return inl(pmbase + 0xF0); +} + +static int __init amd_init (struct pci_dev *dev) +{ + int rc; + u8 rnen; + + DPRINTK ("ENTER\n"); + + pci_read_config_dword(dev, 0x58, &pmbase); + + pmbase &= 0x0000FF00; + + if (pmbase == 0) + { + printk (KERN_ERR PFX "power management base not set\n"); + rc = -EIO; + goto err_out; + } + + pci_read_config_byte(dev, 0x40, &rnen); + rnen |= (1 << 7); /* RNG on */ + pci_write_config_byte(dev, 0x40, rnen); + + pci_read_config_byte(dev, 0x41, &rnen); + rnen |= (1 << 7); /* PMIO enable */ + pci_write_config_byte(dev, 0x41, rnen); + + pr_info( PFX "AMD768 system management I/O registers at 0x%X.\n", + pmbase); + + amd_dev = dev; + + DPRINTK ("EXIT, returning 0\n"); + return 0; + +err_out: + DPRINTK ("EXIT, returning %d\n", rc); + return rc; +} + +static void amd_cleanup(void) +{ + u8 rnen; + + pci_read_config_byte(amd_dev, 0x40, &rnen); + rnen &= ~(1 << 7); /* RNG off */ + pci_write_config_byte(amd_dev, 0x40, rnen); + + /* FIXME: twiddle pmio, also? */ +} + +#ifdef __i386__ +/*********************************************************************** + * + * VIA RNG operations + * + */ + +enum { + VIA_STRFILT_CNT_SHIFT = 16, + VIA_STRFILT_FAIL = (1 << 15), + VIA_STRFILT_ENABLE = (1 << 14), + VIA_RAWBITS_ENABLE = (1 << 13), + VIA_RNG_ENABLE = (1 << 6), + VIA_XSTORE_CNT_MASK = 0x0F, + + VIA_RNG_CHUNK_8 = 0x00, /* 64 rand bits, 64 stored bits */ + VIA_RNG_CHUNK_4 = 0x01, /* 32 rand bits, 32 stored bits */ + VIA_RNG_CHUNK_4_MASK = 0xFFFFFFFF, + VIA_RNG_CHUNK_2 = 0x02, /* 16 rand bits, 32 stored bits */ + VIA_RNG_CHUNK_2_MASK = 0xFFFF, + VIA_RNG_CHUNK_1 = 0x03, /* 8 rand bits, 32 stored bits */ + VIA_RNG_CHUNK_1_MASK = 0xFF, +}; + +static u32 via_rng_datum; + +/* + * Investigate using the 'rep' prefix to obtain 32 bits of random data + * in one insn. The upside is potentially better performance. The + * downside is that the instruction becomes no longer atomic. Due to + * this, just like familiar issues with /dev/random itself, the worst + * case of a 'rep xstore' could potentially pause a cpu for an + * unreasonably long time. In practice, this condition would likely + * only occur when the hardware is failing. (or so we hope :)) + * + * Another possible performance boost may come from simply buffering + * until we have 4 bytes, thus returning a u32 at a time, + * instead of the current u8-at-a-time. + */ + +static inline u32 xstore(u32 *addr, u32 edx_in) +{ + u32 eax_out; + + asm(".byte 0x0F,0xA7,0xC0 /* xstore %%edi (addr=%0) */" + :"=m"(*addr), "=a"(eax_out) + :"D"(addr), "d"(edx_in)); + + return eax_out; +} + +static unsigned int via_data_present(void) +{ + u32 bytes_out; + + /* We choose the recommended 1-byte-per-instruction RNG rate, + * for greater randomness at the expense of speed. Larger + * values 2, 4, or 8 bytes-per-instruction yield greater + * speed at lesser randomness. + * + * If you change this to another VIA_CHUNK_n, you must also + * change the ->n_bytes values in rng_vendor_ops[] tables. + * VIA_CHUNK_8 requires further code changes. + * + * A copy of MSR_VIA_RNG is placed in eax_out when xstore + * completes. + */ + via_rng_datum = 0; /* paranoia, not really necessary */ + bytes_out = xstore(&via_rng_datum, VIA_RNG_CHUNK_1) & VIA_XSTORE_CNT_MASK; + if (bytes_out == 0) + return 0; + + return 1; +} + +static u32 via_data_read(void) +{ + return via_rng_datum; +} + +static int __init via_init(struct pci_dev *dev) +{ + u32 lo, hi, old_lo; + + /* Control the RNG via MSR. Tread lightly and pay very close + * close attention to values written, as the reserved fields + * are documented to be "undefined and unpredictable"; but it + * does not say to write them as zero, so I make a guess that + * we restore the values we find in the register. + */ + rdmsr(MSR_VIA_RNG, lo, hi); + + old_lo = lo; + lo &= ~(0x7f << VIA_STRFILT_CNT_SHIFT); + lo &= ~VIA_XSTORE_CNT_MASK; + lo &= ~(VIA_STRFILT_ENABLE | VIA_STRFILT_FAIL | VIA_RAWBITS_ENABLE); + lo |= VIA_RNG_ENABLE; + + if (lo != old_lo) + wrmsr(MSR_VIA_RNG, lo, hi); + + /* perhaps-unnecessary sanity check; remove after testing if + unneeded */ + rdmsr(MSR_VIA_RNG, lo, hi); + if ((lo & VIA_RNG_ENABLE) == 0) { + printk(KERN_ERR PFX "cannot enable VIA C3 RNG, aborting\n"); + return -ENODEV; + } + + return 0; +} + +static void via_cleanup(void) +{ + /* do nothing */ +} +#endif + + +/*********************************************************************** + * + * /dev/hwrandom character device handling (major 10, minor 183) + * + */ + +static int rng_dev_open (struct inode *inode, struct file *filp) +{ + /* enforce read-only access to this chrdev */ + if ((filp->f_mode & FMODE_READ) == 0) + return -EINVAL; + if (filp->f_mode & FMODE_WRITE) + return -EINVAL; + + return 0; +} + + +static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size, + loff_t * offp) +{ + static DEFINE_SPINLOCK(rng_lock); + unsigned int have_data; + u32 data = 0; + ssize_t ret = 0; + + while (size) { + spin_lock(&rng_lock); + + have_data = 0; + if (rng_ops->data_present()) { + data = rng_ops->data_read(); + have_data = rng_ops->n_bytes; + } + + spin_unlock (&rng_lock); + + while (have_data && size) { + if (put_user((u8)data, buf++)) { + ret = ret ? : -EFAULT; + break; + } + size--; + ret++; + have_data--; + data>>=8; + } + + if (filp->f_flags & O_NONBLOCK) + return ret ? : -EAGAIN; + + if(need_resched()) + { + current->state = TASK_INTERRUPTIBLE; + schedule_timeout(1); + } + else + udelay(200); /* FIXME: We could poll for 250uS ?? */ + + if (signal_pending (current)) + return ret ? : -ERESTARTSYS; + } + return ret; +} + + + +/* + * rng_init_one - look for and attempt to init a single RNG + */ +static int __init rng_init_one (struct pci_dev *dev) +{ + int rc; + + DPRINTK ("ENTER\n"); + + assert(rng_ops != NULL); + + rc = rng_ops->init(dev); + if (rc) + goto err_out; + + rc = misc_register (&rng_miscdev); + if (rc) { + printk (KERN_ERR PFX "misc device register failed\n"); + goto err_out_cleanup_hw; + } + + DPRINTK ("EXIT, returning 0\n"); + return 0; + +err_out_cleanup_hw: + rng_ops->cleanup(); +err_out: + DPRINTK ("EXIT, returning %d\n", rc); + return rc; +} + + + +MODULE_AUTHOR("The Linux Kernel team"); +MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver"); +MODULE_LICENSE("GPL"); + + +/* + * rng_init - initialize RNG module + */ +static int __init rng_init (void) +{ + int rc; + struct pci_dev *pdev = NULL; + const struct pci_device_id *ent; + + DPRINTK ("ENTER\n"); + + /* Probe for Intel, AMD RNGs */ + for_each_pci_dev(pdev) { + ent = pci_match_device (rng_pci_tbl, pdev); + if (ent) { + rng_ops = &rng_vendor_ops[ent->driver_data]; + goto match; + } + } + +#ifdef __i386__ + /* Probe for VIA RNG */ + if (cpu_has_xstore) { + rng_ops = &rng_vendor_ops[rng_hw_via]; + pdev = NULL; + goto match; + } +#endif + + DPRINTK ("EXIT, returning -ENODEV\n"); + return -ENODEV; + +match: + rc = rng_init_one (pdev); + if (rc) + return rc; + + pr_info( RNG_DRIVER_NAME " loaded\n"); + + DPRINTK ("EXIT, returning 0\n"); + return 0; +} + + +/* + * rng_init - shutdown RNG module + */ +static void __exit rng_cleanup (void) +{ + DPRINTK ("ENTER\n"); + + misc_deregister (&rng_miscdev); + + if (rng_ops->cleanup) + rng_ops->cleanup(); + + DPRINTK ("EXIT\n"); +} + + +module_init (rng_init); +module_exit (rng_cleanup); |