* 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
*
#include <linux/module.h>
#include <linux/kernel.h>
-#include <linux/pci.h>
#include <linux/hw_random.h>
+#include <linux/delay.h>
#include <asm/io.h>
#include <asm/msr.h>
#include <asm/cpufeature.h>
+#include <asm/i387.h>
#define PFX KBUILD_MODNAME ": "
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 */
* 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));
+ 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)
{
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
* 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);
+ }
+ return bytes_out ? 1 : 0;
}
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
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);
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");
+MODULE_DESCRIPTION("H/W RNG driver for VIA CPU with PadLock");
MODULE_LICENSE("GPL");