From: Jason A. Donenfeld Jason@zx2c4.com
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@vger.kernel.org # v3.13+ Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Reviewed-by: Christophe Leroy christophe.leroy@csgroup.eu [mpe: Add of_node_put(), use pnv naming, minor change log editing] Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20220621140849.127227-1-Jason@zx2c4.com Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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(-)
--- 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 | \ --- 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 */ --- 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 p 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(unsigne 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(stru
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 devi
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); --- 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)