* [PATCH v3] powerpc/powernv: Use darn instr for random_seed on p9
@ 2017-08-04 1:12 Matt Brown
2017-08-04 17:06 ` Tyrel Datwyler
2017-08-08 10:55 ` [v3] " Michael Ellerman
0 siblings, 2 replies; 6+ messages in thread
From: Matt Brown @ 2017-08-04 1:12 UTC (permalink / raw)
To: linuxppc-dev, mpe
This adds the powernv_get_random_darn function which utilises the darn
instruction, introduced in POWER9. The powernv_get_random_darn function
is used as the ppc_md.get_random_seed on P9.
The DARN instruction can potentially throw an error, so we attempt to
register the powernv_get_random_darn function up to 10 times before
failing.
Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
---
v3:
- add repeat attempts to register the ppc_md.get_random_seed
- fixed the PPC_DARN macro
- move DARN_ERR definition
- fixed commit message
v2:
- remove repeat darn attempts
- move hook to rng_init
---
arch/powerpc/include/asm/ppc-opcode.h | 4 ++++
arch/powerpc/platforms/powernv/rng.c | 35 ++++++++++++++++++++++++++++++++++-
2 files changed, 38 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index c4ced1d..aabd150 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
@@ -325,6 +326,9 @@
/* 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/rng.c b/arch/powerpc/platforms/powernv/rng.c
index 5dcbdea..83b925c 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -16,11 +16,13 @@
#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>
+#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
struct powernv_rng {
void __iomem *regs;
@@ -67,6 +69,21 @@ int powernv_get_random_real_mode(unsigned long *v)
return 1;
}
+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;
+}
+
int powernv_get_random_long(unsigned long *v)
{
struct powernv_rng *rng;
@@ -135,8 +152,9 @@ static __init int rng_create(struct device_node *dn)
static __init int rng_init(void)
{
+ unsigned long darn_test;
struct device_node *dn;
- int rc;
+ int rc, i;
for_each_compatible_node(dn, NULL, "ibm,power-rng") {
rc = rng_create(dn);
@@ -150,6 +168,21 @@ static __init int rng_init(void)
of_platform_device_create(dn, NULL, NULL);
}
+ if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+ for (i = 0; i < 10; i++) {
+ if (powernv_get_random_darn(&darn_test)) {
+ ppc_md.get_random_seed =
+ powernv_get_random_darn;
+ break;
+ }
+
+ if (i == 9) {
+ pr_warn("Failed to use powernv_get_random_darn"\
+ "as get_random_seed");
+ }
+ }
+ }
+
return 0;
}
machine_subsys_initcall(powernv, rng_init);
--
2.9.3
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v3] powerpc/powernv: Use darn instr for random_seed on p9
2017-08-04 1:12 [PATCH v3] powerpc/powernv: Use darn instr for random_seed on p9 Matt Brown
@ 2017-08-04 17:06 ` Tyrel Datwyler
2017-08-07 2:00 ` Matt Brown
2017-08-08 10:55 ` [v3] " Michael Ellerman
1 sibling, 1 reply; 6+ messages in thread
From: Tyrel Datwyler @ 2017-08-04 17:06 UTC (permalink / raw)
To: Matt Brown, linuxppc-dev, mpe
On 08/03/2017 06:12 PM, Matt Brown wrote:
> This adds the powernv_get_random_darn function which utilises the darn
> instruction, introduced in POWER9. The powernv_get_random_darn function
> is used as the ppc_md.get_random_seed on P9.
>
> The DARN instruction can potentially throw an error, so we attempt to
> register the powernv_get_random_darn function up to 10 times before
> failing.
>
> Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
> ---
> v3:
> - add repeat attempts to register the ppc_md.get_random_seed
> - fixed the PPC_DARN macro
> - move DARN_ERR definition
> - fixed commit message
> v2:
> - remove repeat darn attempts
> - move hook to rng_init
> ---
> arch/powerpc/include/asm/ppc-opcode.h | 4 ++++
> arch/powerpc/platforms/powernv/rng.c | 35 ++++++++++++++++++++++++++++++++++-
> 2 files changed, 38 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
> index c4ced1d..aabd150 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
> @@ -325,6 +326,9 @@
>
> /* 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/rng.c b/arch/powerpc/platforms/powernv/rng.c
> index 5dcbdea..83b925c 100644
> --- a/arch/powerpc/platforms/powernv/rng.c
> +++ b/arch/powerpc/platforms/powernv/rng.c
> @@ -16,11 +16,13 @@
> #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>
>
> +#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
>
> struct powernv_rng {
> void __iomem *regs;
> @@ -67,6 +69,21 @@ int powernv_get_random_real_mode(unsigned long *v)
> return 1;
> }
>
> +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;
> +}
> +
> int powernv_get_random_long(unsigned long *v)
> {
> struct powernv_rng *rng;
> @@ -135,8 +152,9 @@ static __init int rng_create(struct device_node *dn)
>
> static __init int rng_init(void)
> {
> + unsigned long darn_test;
> struct device_node *dn;
> - int rc;
> + int rc, i;
>
> for_each_compatible_node(dn, NULL, "ibm,power-rng") {
> rc = rng_create(dn);
> @@ -150,6 +168,21 @@ static __init int rng_init(void)
> of_platform_device_create(dn, NULL, NULL);
> }
>
> + if (cpu_has_feature(CPU_FTR_ARCH_300)) {
> + for (i = 0; i < 10; i++) {
> + if (powernv_get_random_darn(&darn_test)) {
> + ppc_md.get_random_seed =
> + powernv_get_random_darn;
> + break;
If you return directly here you can avoid the (i == 9) conditional every iteration of the
loop by moving the pr_warn to just outside the loop.
-Tyrel
> + }
> +
> + if (i == 9) {
> + pr_warn("Failed to use powernv_get_random_darn"\
> + "as get_random_seed");
> + }
> + }
> + }
> +
> return 0;
> }
> machine_subsys_initcall(powernv, rng_init);
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v3] powerpc/powernv: Use darn instr for random_seed on p9
2017-08-04 17:06 ` Tyrel Datwyler
@ 2017-08-07 2:00 ` Matt Brown
2017-08-07 5:41 ` Michael Ellerman
0 siblings, 1 reply; 6+ messages in thread
From: Matt Brown @ 2017-08-07 2:00 UTC (permalink / raw)
To: Tyrel Datwyler
Cc: open list:LINUX FOR POWERPC (32-BIT AND 64-BIT), Michael Ellerman
On Sat, Aug 5, 2017 at 3:06 AM, Tyrel Datwyler
<tyreld@linux.vnet.ibm.com> wrote:
> On 08/03/2017 06:12 PM, Matt Brown wrote:
>> This adds the powernv_get_random_darn function which utilises the darn
>> instruction, introduced in POWER9. The powernv_get_random_darn function
>> is used as the ppc_md.get_random_seed on P9.
>>
>> The DARN instruction can potentially throw an error, so we attempt to
>> register the powernv_get_random_darn function up to 10 times before
>> failing.
>>
>> Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
>> ---
>> v3:
>> - add repeat attempts to register the ppc_md.get_random_seed
>> - fixed the PPC_DARN macro
>> - move DARN_ERR definition
>> - fixed commit message
>> v2:
>> - remove repeat darn attempts
>> - move hook to rng_init
>> ---
>> arch/powerpc/include/asm/ppc-opcode.h | 4 ++++
>> arch/powerpc/platforms/powernv/rng.c | 35 ++++++++++++++++++++++++++++++++++-
>> 2 files changed, 38 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
>> index c4ced1d..aabd150 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
>> @@ -325,6 +326,9 @@
>>
>> /* 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/rng.c b/arch/powerpc/platforms/powernv/rng.c
>> index 5dcbdea..83b925c 100644
>> --- a/arch/powerpc/platforms/powernv/rng.c
>> +++ b/arch/powerpc/platforms/powernv/rng.c
>> @@ -16,11 +16,13 @@
>> #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>
>>
>> +#define DARN_ERR 0xFFFFFFFFFFFFFFFFul
>>
>> struct powernv_rng {
>> void __iomem *regs;
>> @@ -67,6 +69,21 @@ int powernv_get_random_real_mode(unsigned long *v)
>> return 1;
>> }
>>
>> +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;
>> +}
>> +
>> int powernv_get_random_long(unsigned long *v)
>> {
>> struct powernv_rng *rng;
>> @@ -135,8 +152,9 @@ static __init int rng_create(struct device_node *dn)
>>
>> static __init int rng_init(void)
>> {
>> + unsigned long darn_test;
>> struct device_node *dn;
>> - int rc;
>> + int rc, i;
>>
>> for_each_compatible_node(dn, NULL, "ibm,power-rng") {
>> rc = rng_create(dn);
>> @@ -150,6 +168,21 @@ static __init int rng_init(void)
>> of_platform_device_create(dn, NULL, NULL);
>> }
>>
>> + if (cpu_has_feature(CPU_FTR_ARCH_300)) {
>> + for (i = 0; i < 10; i++) {
>> + if (powernv_get_random_darn(&darn_test)) {
>> + ppc_md.get_random_seed =
>> + powernv_get_random_darn;
>> + break;
>
> If you return directly here you can avoid the (i == 9) conditional every iteration of the
> loop by moving the pr_warn to just outside the loop.
That's true, although it is very unlikely for the
powernv_get_random_darn to fail. So in practice we should never reach
the (i == 9) conditional.
The loop is more of a backup in the rare case that it does fail.
Thanks,
Matt
>
> -Tyrel
>
>> + }
>> +
>> + if (i == 9) {
>> + pr_warn("Failed to use powernv_get_random_darn"\
>> + "as get_random_seed");
>> + }
>> + }
>> + }
>> +
>> return 0;
>> }
>> machine_subsys_initcall(powernv, rng_init);
>>
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v3] powerpc/powernv: Use darn instr for random_seed on p9
2017-08-07 2:00 ` Matt Brown
@ 2017-08-07 5:41 ` Michael Ellerman
2017-08-07 10:32 ` Michael Ellerman
0 siblings, 1 reply; 6+ messages in thread
From: Michael Ellerman @ 2017-08-07 5:41 UTC (permalink / raw)
To: Matt Brown, Tyrel Datwyler
Cc: open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)
Matt Brown <matthew.brown.dev@gmail.com> writes:
> On Sat, Aug 5, 2017 at 3:06 AM, Tyrel Datwyler <tyreld@linux.vnet.ibm.com> wrote:
>> On 08/03/2017 06:12 PM, Matt Brown wrote:
>>> @@ -135,8 +152,9 @@ static __init int rng_create(struct device_node *dn)
>>>
>>> static __init int rng_init(void)
>>> {
>>> + unsigned long darn_test;
>>> struct device_node *dn;
>>> - int rc;
>>> + int rc, i;
>>>
>>> for_each_compatible_node(dn, NULL, "ibm,power-rng") {
>>> rc = rng_create(dn);
>>> @@ -150,6 +168,21 @@ static __init int rng_init(void)
>>> of_platform_device_create(dn, NULL, NULL);
>>> }
>>>
>>> + if (cpu_has_feature(CPU_FTR_ARCH_300)) {
>>> + for (i = 0; i < 10; i++) {
>>> + if (powernv_get_random_darn(&darn_test)) {
>>> + ppc_md.get_random_seed =
>>> + powernv_get_random_darn;
>>> + break;
>>
>> If you return directly here you can avoid the (i == 9) conditional every iteration of the
>> loop by moving the pr_warn to just outside the loop.
>
> That's true, although it is very unlikely for the
> powernv_get_random_darn to fail. So in practice we should never reach
> the (i == 9) conditional.
> The loop is more of a backup in the rare case that it does fail.
All true, the runtime overhead is really not an issue. It's more that
testing for loop almost-termination in the loop is a bit gross :)
I think the best solution is to just pull it out into a separate
function, it also avoids adding sometimes unused variables to the outer
function, eg:
static int initialise_darn(void)
{
unsigned long val;
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;
}
cheers
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v3] powerpc/powernv: Use darn instr for random_seed on p9
2017-08-07 5:41 ` Michael Ellerman
@ 2017-08-07 10:32 ` Michael Ellerman
0 siblings, 0 replies; 6+ messages in thread
From: Michael Ellerman @ 2017-08-07 10:32 UTC (permalink / raw)
To: Matt Brown, Tyrel Datwyler
Cc: open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)
Michael Ellerman <mpe@ellerman.id.au> writes:
> Matt Brown <matthew.brown.dev@gmail.com> writes:
>> On Sat, Aug 5, 2017 at 3:06 AM, Tyrel Datwyler <tyreld@linux.vnet.ibm.com> wrote:
>>> On 08/03/2017 06:12 PM, Matt Brown wrote:
>>>> @@ -135,8 +152,9 @@ static __init int rng_create(struct device_node *dn)
>>>> @@ -150,6 +168,21 @@ static __init int rng_init(void)
>>>> of_platform_device_create(dn, NULL, NULL);
>>>> }
>>>>
>>>> + if (cpu_has_feature(CPU_FTR_ARCH_300)) {
>>>> + for (i = 0; i < 10; i++) {
>>>> + if (powernv_get_random_darn(&darn_test)) {
>>>> + ppc_md.get_random_seed =
>>>> + powernv_get_random_darn;
>>>> + break;
>>>
>>> If you return directly here you can avoid the (i == 9) conditional every iteration of the
>>> loop by moving the pr_warn to just outside the loop.
>>
>> That's true, although it is very unlikely for the
>> powernv_get_random_darn to fail. So in practice we should never reach
>> the (i == 9) conditional.
>> The loop is more of a backup in the rare case that it does fail.
>
> All true, the runtime overhead is really not an issue. It's more that
> testing for loop almost-termination in the loop is a bit gross :)
>
> I think the best solution is to just pull it out into a separate
> function, it also avoids adding sometimes unused variables to the outer
> function, eg:
>
> static int initialise_darn(void)
> ...
I decided this patch had reached my bike-shedding threshold, so I just
unilaterally changed it to the way I liked it and applied it :)
All the bugs are mine.
cheers
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [v3] powerpc/powernv: Use darn instr for random_seed on p9
2017-08-04 1:12 [PATCH v3] powerpc/powernv: Use darn instr for random_seed on p9 Matt Brown
2017-08-04 17:06 ` Tyrel Datwyler
@ 2017-08-08 10:55 ` Michael Ellerman
1 sibling, 0 replies; 6+ messages in thread
From: Michael Ellerman @ 2017-08-08 10:55 UTC (permalink / raw)
To: Matt Brown, linuxppc-dev
On Fri, 2017-08-04 at 01:12:18 UTC, Matt Brown wrote:
> This adds the powernv_get_random_darn function which utilises the darn
> instruction, introduced in POWER9. The powernv_get_random_darn function
> is used as the ppc_md.get_random_seed on P9.
>
> The DARN instruction can potentially throw an error, so we attempt to
> register the powernv_get_random_darn function up to 10 times before
> failing.
>
> Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/e66ca3db5917f4bcad039d3a3df9f1
cheers
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-08-08 10:55 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-08-04 1:12 [PATCH v3] powerpc/powernv: Use darn instr for random_seed on p9 Matt Brown
2017-08-04 17:06 ` Tyrel Datwyler
2017-08-07 2:00 ` Matt Brown
2017-08-07 5:41 ` Michael Ellerman
2017-08-07 10:32 ` Michael Ellerman
2017-08-08 10:55 ` [v3] " Michael Ellerman
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).