diff options
Diffstat (limited to 'drivers/char/hw_random/via-rng.c')
| -rw-r--r-- | drivers/char/hw_random/via-rng.c | 78 |
1 files changed, 63 insertions, 15 deletions
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c index 0e786b617bb..de5a6dcfb3e 100644 --- a/drivers/char/hw_random/via-rng.c +++ b/drivers/char/hw_random/via-rng.c @@ -11,7 +11,7 @@ * derived from * * Hardware driver for the AMD 768 Random Number Generator (RNG) - * (c) Copyright 2001 Red Hat Inc <alan@redhat.com> + * (c) Copyright 2001 Red Hat Inc * * derived from * @@ -24,16 +24,18 @@ * warranty of any kind, whether express or implied. */ +#include <crypto/padlock.h> #include <linux/module.h> #include <linux/kernel.h> -#include <linux/pci.h> #include <linux/hw_random.h> +#include <linux/delay.h> +#include <asm/cpu_device_id.h> #include <asm/io.h> #include <asm/msr.h> #include <asm/cpufeature.h> +#include <asm/i387.h> -#define PFX KBUILD_MODNAME ": " enum { @@ -42,6 +44,8 @@ enum { VIA_STRFILT_ENABLE = (1 << 14), VIA_RAWBITS_ENABLE = (1 << 13), VIA_RNG_ENABLE = (1 << 6), + VIA_NOISESRC1 = (1 << 8), + VIA_NOISESRC2 = (1 << 9), VIA_XSTORE_CNT_MASK = 0x0F, VIA_RNG_CHUNK_8 = 0x00, /* 64 rand bits, 64 stored bits */ @@ -65,23 +69,32 @@ enum { * 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. + * + * Padlock instructions can generate a spurious DNA fault, so + * we have to call them in the context of irq_ts_save/restore() */ static inline u32 xstore(u32 *addr, u32 edx_in) { u32 eax_out; + int ts_state; + + ts_state = irq_ts_save(); asm(".byte 0x0F,0xA7,0xC0 /* xstore %%edi (addr=%0) */" - :"=m"(*addr), "=a"(eax_out) - :"D"(addr), "d"(edx_in)); + : "=m" (*addr), "=a" (eax_out), "+d" (edx_in), "+D" (addr)); + irq_ts_restore(ts_state); return eax_out; } -static int via_rng_data_present(struct hwrng *rng) +static int via_rng_data_present(struct hwrng *rng, int wait) { + char buf[16 + PADLOCK_ALIGNMENT - STACK_ALIGN] __attribute__ + ((aligned(STACK_ALIGN))); + u32 *via_rng_datum = (u32 *)PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT); u32 bytes_out; - u32 *via_rng_datum = (u32 *)(&rng->priv); + int i; /* We choose the recommended 1-byte-per-instruction RNG rate, * for greater randomness at the expense of speed. Larger @@ -96,12 +109,16 @@ static int via_rng_data_present(struct hwrng *rng) * completes. */ - *via_rng_datum = 0; /* paranoia, not really necessary */ - bytes_out = xstore(via_rng_datum, VIA_RNG_CHUNK_1); - bytes_out &= VIA_XSTORE_CNT_MASK; - if (bytes_out == 0) - return 0; - return 1; + for (i = 0; i < 20; i++) { + *via_rng_datum = 0; /* paranoia, not really necessary */ + bytes_out = xstore(via_rng_datum, VIA_RNG_CHUNK_1); + bytes_out &= VIA_XSTORE_CNT_MASK; + if (bytes_out || !wait) + break; + udelay(10); + } + rng->priv = *via_rng_datum; + return bytes_out ? 1 : 0; } static int via_rng_data_read(struct hwrng *rng, u32 *data) @@ -115,8 +132,22 @@ static int via_rng_data_read(struct hwrng *rng, u32 *data) static int via_rng_init(struct hwrng *rng) { + struct cpuinfo_x86 *c = &cpu_data(0); u32 lo, hi, old_lo; + /* VIA Nano CPUs don't have the MSR_VIA_RNG anymore. The RNG + * is always enabled if CPUID rng_en is set. There is no + * RNG configuration like it used to be the case in this + * register */ + if ((c->x86 == 6) && (c->x86_model >= 0x0f)) { + if (!cpu_has_xstore_enabled) { + printk(KERN_ERR PFX "can't enable hardware RNG " + "if XSTORE is not enabled\n"); + return -ENODEV; + } + return 0; + } + /* 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 @@ -130,6 +161,17 @@ static int via_rng_init(struct hwrng *rng) lo &= ~VIA_XSTORE_CNT_MASK; lo &= ~(VIA_STRFILT_ENABLE | VIA_STRFILT_FAIL | VIA_RAWBITS_ENABLE); lo |= VIA_RNG_ENABLE; + lo |= VIA_NOISESRC1; + + /* Enable secondary noise source on CPUs where it is present. */ + + /* Nehemiah stepping 8 and higher */ + if ((c->x86_model == 9) && (c->x86_mask > 7)) + lo |= VIA_NOISESRC2; + + /* Esther */ + if (c->x86_model >= 10) + lo |= VIA_NOISESRC2; if (lo != old_lo) wrmsr(MSR_VIA_RNG, lo, hi); @@ -176,8 +218,14 @@ static void __exit mod_exit(void) hwrng_unregister(&via_rng); } -subsys_initcall(mod_init); +module_init(mod_init); module_exit(mod_exit); -MODULE_DESCRIPTION("H/W RNG driver for VIA chipsets"); +static struct x86_cpu_id __maybe_unused via_rng_cpu_id[] = { + X86_FEATURE_MATCH(X86_FEATURE_XSTORE), + {} +}; + +MODULE_DESCRIPTION("H/W RNG driver for VIA CPU with PadLock"); MODULE_LICENSE("GPL"); +MODULE_DEVICE_TABLE(x86cpu, via_rng_cpu_id); |