commit f3eac426657d985b97c92fa5f7ae1d43f04721f3 upstream.
The platform's RNG must be available before random_init() in order to be
useful for initial seeding, which in turn means that it needs to be
called from setup_arch(), rather than from an init call.
Complicating things, however, is that POWER8 systems need some per-cpu
state and kmalloc, which isn't available at this stage. So we split
things up into an early phase and a later opportunistic phase. This
commit also removes some noisy log messages that don't add much.
Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
Cc: stable@xxxxxxxxxxxxxxx # v3.13+
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
[mpe: Add of_node_put(), use pnv naming, minor change log editing]
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220621140849.127227-1-Jason@xxxxxxxxx
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
---
arch/powerpc/include/asm/ppc-opcode.h | 4 ++
arch/powerpc/platforms/powernv/powernv.h | 2 +
arch/powerpc/platforms/powernv/rng.c | 91 ++++++++++++++++++++----
arch/powerpc/platforms/powernv/setup.c | 2 +
4 files changed, 85 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index b7067590f15c..8cb3c929641a 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -134,6 +134,7 @@
#define PPC_INST_COPY 0x7c00060c
#define PPC_INST_COPY_FIRST 0x7c20060c
#define PPC_INST_CP_ABORT 0x7c00068c
+#define PPC_INST_DARN 0x7c0005e6
#define PPC_INST_DCBA 0x7c0005ec
#define PPC_INST_DCBA_MASK 0xfc0007fe
#define PPC_INST_DCBAL 0x7c2005ec
@@ -328,6 +329,9 @@
/* Deal with instructions that older assemblers aren't aware of */
#define PPC_CP_ABORT stringify_in_c(.long PPC_INST_CP_ABORT)
+#define PPC_DARN(t, l) stringify_in_c(.long PPC_INST_DARN | \
+ ___PPC_RT(t) | \
+ (((l) & 0x3) << 16))
#define PPC_DCBAL(a, b) stringify_in_c(.long PPC_INST_DCBAL | \
__PPC_RA(a) | __PPC_RB(b))
#define PPC_DCBZL(a, b) stringify_in_c(.long PPC_INST_DCBZL | \
diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index da7c843ac7f1..e98e14a5db4d 100644
--- a/arch/powerpc/platforms/powernv/powernv.h
+++ b/arch/powerpc/platforms/powernv/powernv.h
@@ -27,4 +27,6 @@ extern void opal_event_shutdown(void);
bool cpu_core_split_required(void);
+void pnv_rng_init(void);
+
#endif /* _POWERNV_H */
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index 5dcbdea1afac..dc13ed3f6c2b 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -16,11 +16,14 @@
#include <linux/slab.h>
#include <linux/smp.h>
#include <asm/archrandom.h>
+#include <asm/cputable.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#include <asm/smp.h>
+#include "powernv.h"
+#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
struct powernv_rng {
void __iomem *regs;
@@ -30,7 +33,6 @@ struct powernv_rng {
static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
-
int powernv_hwrng_present(void)
{
struct powernv_rng *rng;
@@ -45,7 +47,11 @@ static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
unsigned long parity;
/* Calculate the parity of the value */
- asm ("popcntd %0,%1" : "=r" (parity) : "r" (val));
+ asm (".machine push; \
+ .machine power7; \
+ popcntd %0,%1; \
+ .machine pop;"
+ : "=r" (parity) : "r" (val));
/* xor our value with the previous mask */
val ^= rng->mask;
@@ -67,6 +73,38 @@ int powernv_get_random_real_mode(unsigned long *v)
return 1;
}
+static int powernv_get_random_darn(unsigned long *v)
+{
+ unsigned long val;
+
+ /* Using DARN with L=1 - 64-bit conditioned random number */
+ asm volatile(PPC_DARN(%0, 1) : "=r"(val));
+
+ if (val == DARN_ERR)
+ return 0;
+
+ *v = val;
+
+ return 1;
+}
+
+static int __init initialise_darn(void)
+{
+ unsigned long val;
+ int i;
+
+ if (!cpu_has_feature(CPU_FTR_ARCH_300))
+ return -ENODEV;
+
+ for (i = 0; i < 10; i++) {
+ if (powernv_get_random_darn(&val)) {
+ ppc_md.get_random_seed = powernv_get_random_darn;
+ return 0;
+ }
+ }
+ return -EIO;
+}
+
int powernv_get_random_long(unsigned long *v)
{
struct powernv_rng *rng;
@@ -88,7 +126,7 @@ static __init void rng_init_per_cpu(struct powernv_rng *rng,
chip_id = of_get_ibm_chip_id(dn);
if (chip_id == -1)
- pr_warn("No ibm,chip-id found for %s.\n", dn->full_name);
+ pr_warn("No ibm,chip-id found for %pOF.\n", dn);
for_each_possible_cpu(cpu) {
if (per_cpu(powernv_rng, cpu) == NULL ||
@@ -126,30 +164,55 @@ static __init int rng_create(struct device_node *dn)
rng_init_per_cpu(rng, dn);
- pr_info_once("Registering arch random hook.\n");
-
ppc_md.get_random_seed = powernv_get_random_long;
return 0;
}
-static __init int rng_init(void)
+static int __init pnv_get_random_long_early(unsigned long *v)
{
struct device_node *dn;
- int rc;
+
+ if (!slab_is_available())
+ return 0;
+
+ if (cmpxchg(&ppc_md.get_random_seed, pnv_get_random_long_early,
+ NULL) != pnv_get_random_long_early)
+ return 0;
for_each_compatible_node(dn, NULL, "ibm,power-rng") {
- rc = rng_create(dn);
- if (rc) {
- pr_err("Failed creating rng for %s (%d).\n",
- dn->full_name, rc);
+ if (rng_create(dn))
continue;
- }
-
/* Create devices for hwrng driver */
of_platform_device_create(dn, NULL, NULL);
}
+ if (!ppc_md.get_random_seed)
+ return 0;
+ return ppc_md.get_random_seed(v);
+}
+
+void __init pnv_rng_init(void)
+{
+ struct device_node *dn;
+
+ /* Prefer darn over the rest. */
+ if (!initialise_darn())
+ return;
+
+ dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng");
+ if (dn)
+ ppc_md.get_random_seed = pnv_get_random_long_early;
+
+ of_node_put(dn);
+}
+
+static int __init pnv_rng_late_init(void)
+{
+ unsigned long v;
+ /* In case it wasn't called during init for some other reason. */
+ if (ppc_md.get_random_seed == pnv_get_random_long_early)
+ pnv_get_random_long_early(&v);
return 0;
}
-machine_subsys_initcall(powernv, rng_init);
+machine_subsys_initcall(powernv, pnv_rng_late_init);
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index b77d5eed9520..e97b714d30d7 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -168,6 +168,8 @@ static void __init pnv_setup_arch(void)
powersave_nap = 1;
/* XXX PMCS */
+
+ pnv_rng_init();
}
static void __init pnv_init(void)
--
2.35.1
