/* Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG) (c) Copyright 2003 Red Hat Inc derived from Hardware driver for the AMD 768 Random Number Generator (RNG) (c) Copyright 2001 Red Hat Inc derived from Hardware driver for Intel i810 Random Number Generator (RNG) Copyright 2000,2001 Jeff Garzik Copyright 2000,2001 Philipp Rumpf 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 #include #include #include #include #include #include #include #include #include #include #include #ifdef __i386__ #include #include #endif #include #include /* * 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_id(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);