lkml.org 
[lkml]   [2019]   [Feb]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [v4 PATCH 8/8] RISC-V: Assign hwcap as per comman capabilities.
From
Date
On 2/12/19 3:25 AM, Johan Hovold wrote:
> On Tue, Feb 12, 2019 at 03:10:12AM -0800, Atish Patra wrote:
>> Currently, we set hwcap based on first valid hart from DT. This may not
>> be correct always as that hart might not be current booting cpu or may
>> have a different capability.
>>
>> Set hwcap as the capabilities supported by all possible harts with "okay"
>> status.
>>
>> Signed-off-by: Atish Patra <atish.patra@wdc.com>
>> ---
>> arch/riscv/kernel/cpufeature.c | 41 ++++++++++++++++++++++-------------------
>> 1 file changed, 22 insertions(+), 19 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
>> index e7a4701f..a1e4fb34 100644
>> --- a/arch/riscv/kernel/cpufeature.c
>> +++ b/arch/riscv/kernel/cpufeature.c
>> @@ -20,6 +20,7 @@
>> #include <linux/of.h>
>> #include <asm/processor.h>
>> #include <asm/hwcap.h>
>> +#include <asm/smp.h>
>>
>> unsigned long elf_hwcap __read_mostly;
>> #ifdef CONFIG_FPU
>> @@ -42,28 +43,30 @@ void riscv_fill_hwcap(void)
>>
>> elf_hwcap = 0;
>>
>> - /*
>> - * We don't support running Linux on hertergenous ISA systems. For
>> - * now, we just check the ISA of the first "okay" processor.
>> - */
>> for_each_of_cpu_node(node) {
>> - if (riscv_of_processor_hartid(node) >= 0)
>> - break;
>> - }
>> - if (!node) {
>> - pr_warn("Unable to find \"cpu\" devicetree entry\n");
>> - return;
>> - }
>> + unsigned long this_hwcap = 0;
>>
>> - if (of_property_read_string(node, "riscv,isa", &isa)) {
>> - pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
>> - of_node_put(node);
>> - return;
>> - }
>> - of_node_put(node);
>> + if (riscv_of_processor_hartid(node) < 0)
>> + continue;
>>

>> - for (i = 0; i < strlen(isa); ++i)
>> - elf_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
>> + if (of_property_read_string(node, "riscv,isa", &isa)) {
>> + pr_warn("Unable to find \"riscv,isa\" devicetree entry\n");
>> + return;
>
> Did you want "continue" here to continue processing the other harts?
>

Hmm. If a cpu node doesn't have isa in DT, that means DT is wrong. A
"continue" here will let user space use other harts just with a warning
message?

Returning here will not set elf_hwcap which forces the user to fix the
DT. I am not sure what should be the defined behavior in this case.

Any thoughts ?
> Note that you currently leak the device node when returning.
>
Ahh yes. I will fix it if we continue to return in the error case.

Regards,
Atish
> Johan
>

\
 
 \ /
  Last update: 2019-02-12 20:59    [W:0.043 / U:0.268 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site