Add plictool to dump PLIC state

lagarto-ox.nix

@@ -166,6 +166,7 @@
       extraUtilsCommands = ''
         cp -a ${pkgs.csrtool}/bin/csrtool $out/bin
         cp -a ${pkgs.memtool}/bin/memtool $out/bin
+        cp -a ${pkgs.plictool}/bin/plictool $out/bin
       '';
 
       # Write a counter to the DMA region, so we can check the kernel is not

overlay.nix

@@ -69,6 +69,22 @@ final: prev:
     '';
   };
 
+  plictool = prev.pkgsStatic.stdenv.mkDerivation {
+    name = "plictool";
+    src = ./tools/plictool.c;
+    unpackPhase = ''
+      cp ${./tools/plictool.c} plictool.c
+    '';
+    dontConfigure = true;
+    buildPhase = ''
+      $CC -static plictool.c -o plictool
+    '';
+    installPhase = ''
+      mkdir -p $out/bin
+      cp plictool $out/bin/
+    '';
+  };
+
   bitstreams = builtins.fetchGit {
     url = "git@bscpm03.bsc.es:rarias/bitstreams.git";
     rev = "097dad3e888f630ad6ec7e7056ee1b3fcb03400b";

tools/plictool.c

@@ -0,0 +1,131 @@
+/* Copyright (c) 2024 Barcelona Supercomputing Center (BSC)
+ * SPDX-License-Identifier: MIT
+ * Author: Rodrigo Arias Mallo <rodrigo.arias@bsc.es> */
+
+/* Small utility to dump the state of the PLIC. */
+
+/* Changelog:
+ *   v0.0.1 (2024-09-03): Initial version.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <errno.h>
+
+const char *plic_address_str = "0x40800000";
+long ncontexts = 15872L;
+long maxsources = 1024L;
+long nsources = 1024L;
+
+static void
+usage(void)
+{
+	printf("plictool v0.0.1 - Rodrigo Arias Mallo <rodrigo.arias@bsc.es>\n");
+
+	printf(
+"Usage: plictool [-a addr] [-s nsources] [-c ncontexts]\n");
+	exit(1);
+}
+
+void dump_sources(void *base)
+{
+	for (long s = 0; s < nsources; s++) {
+		int printed_source = 0;
+
+		uint32_t *pending_reg  = base + 0x1000L + (s / 32L) * 4L;
+		long shift = s % 32L;
+		uint32_t pending = ((*pending_reg) >> shift) & 1;
+		uint32_t *priority_reg = base + 0x0000L + (s * 4L);
+		uint32_t priority = *priority_reg;
+
+		const char *fmt =
+			"src=%ld pend=%u prio=%u";
+
+		if (pending || priority) {
+			printf(fmt, s, pending, priority);
+			printed_source = 1;
+		}
+
+		int first_context = 1;
+		for (long c = 0; c < ncontexts; c++) {
+			uint32_t *enable_reg = base + 0x2000L + 0x80L * c + (s / 32L) * 4L;
+			uint32_t enabled = ((*enable_reg) >> shift) & 1;
+			uint32_t *threshold_reg = base + 0x200000L + (c * 0x1000L);
+			uint32_t threshold = *threshold_reg;
+
+			if (!enabled)
+				continue;
+
+			if (!printed_source) {
+				printf(fmt, s, pending, priority);
+				printed_source = 1;
+			}
+
+			printf(" ctx=%ld thre=%u", c, threshold);
+		}
+
+		if (printed_source)
+			printf("\n");
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "a:hs:c:")) != -1) {
+		switch (opt) {
+			case 'a':
+				plic_address_str = optarg;
+				break;
+			case 's':
+				nsources = atol(optarg);
+				break;
+			case 'c':
+				ncontexts = atol(optarg);
+				break;
+			case 'h':
+			default: /* '?' */
+				usage();
+		}
+	}
+
+	off_t plic_address = (off_t) strtoll(plic_address_str, NULL, 16);
+
+	printf("plic=0x%08x nsources=%ld ncontexts=%ld\n",
+			plic_address, nsources, ncontexts);
+
+	int fd = open("/dev/mem", O_RDWR | O_SYNC);
+
+	if (fd == -1) {
+		perror("cannot open /dev/mem");
+		exit(1);
+	}
+
+	size_t map_size = 0x4000000UL;
+	void *map_base = mmap(0, map_size, PROT_READ | PROT_WRITE, MAP_SHARED,
+			fd, plic_address);
+
+	if (map_base == MAP_FAILED) {
+		perror("mmap failed");
+		if (errno == EPERM) {
+			fprintf(stderr,	"Have you disabled 'CONFIG_STRICT_DEVMEM' and "
+					"'CONFIG_IO_STRICT_DEVMEM' in the kernel config?\n"
+					"Hint: zgrep STRICT_DEVMEM /proc/config.gz\n");
+		}
+		exit(1);
+	}
+
+	dump_sources(map_base);
+
+	munmap(map_base, map_size);
+
+	close(fd);
+
+	return 0;
+}