plic: Fix cpuid handling

Make `cpu' signed so that the possible return value -1 from
plic_get_cpuid() gets handled correctly in the (cpu < 0) condition.
This prevents plic_attach() from updating sc_contexts[] out of bounds.

When plic_get_cpuid() returns -1, ignore the entry and continue
processing. The error is not fatal. It is normal that secondary CPUs
are not found when running a non-MULTIPROCESSOR kernel on
a multiprocessor machine.

OK kettenis@

diff --git a/sys/arch/riscv64/dev/plic.c b/sys/arch/riscv64/dev/plic.c
index f058d66..a9f53b5 100644 (file)
--- a/sys/arch/riscv64/dev/plic.c
+++ b/sys/arch/riscv64/dev/plic.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: plic.c,v 1.8 2022/01/03 03:06:50 jsg Exp $    */
+/*     $OpenBSD: plic.c,v 1.9 2022/01/18 07:44:37 visa Exp $   */
 
 /*
  * Copyright (c) 2020, Mars Li <mengshi.li.mars@gmail.com>
@@ -162,7 +162,7 @@ plic_attach(struct device *parent, struct device *dev, void *aux)
        struct fdt_attach_args *faa;
        uint32_t *cells;
        uint32_t irq;
-       uint32_t cpu;
+       int cpu;
        int node;
        int len;
        int ncell;
@@ -251,11 +251,8 @@ plic_attach(struct device *parent, struct device *dev, void *aux)
 
                /* Get the corresponding cpuid. */
                cpu = plic_get_cpuid(OF_getnodebyphandle(cells[i]));
-               if (cpu < 0) {
-                       printf(": invalid hart!\n");
-                       free(cells, M_TEMP, len);
-                       return;
-               }
+               if (cpu < 0)
+                       continue;
 
                /*
                 * Set the enable and context register offsets for the CPU.