RISC-V: Assign hwcap as per comman capabilities.

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>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index e7a4701f02563504f2f8cfd7b773c422b4424fe6..bc29b010b722f62d18fac0b7bd79c5adb77d4d4f 100644 (file)
--- 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");
+                       continue;
+               }
+
+               for (i = 0; i < strlen(isa); ++i)
+                       this_hwcap |= isa2hwcap[(unsigned char)(isa[i])];
+
+               /*
+                * All "okay" hart should have same isa. Set HWCAP based on
+                * common capabilities of every "okay" hart, in case they don't
+                * have.
+                */
+               if (elf_hwcap)
+                       elf_hwcap &= this_hwcap;
+               else
+                       elf_hwcap = this_hwcap;
+       }
 
        /* We don't support systems with F but without D, so mask those out
         * here. */