/* 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()) schedule_timeout_interruptible(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);