1 files changed, 252 insertions, 0 deletions
diff --git a/tools/perf/tests/vmlinux-kallsyms.c b/tools/perf/tests/vmlinux-kallsyms.c
new file mode 100644
index 000000000..193b7c91b
--- /dev/null
+++ b/tools/perf/tests/vmlinux-kallsyms.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/compiler.h>
+#include <linux/rbtree.h>
+#include <inttypes.h>
+#include <string.h>
+#include <stdlib.h>
+#include "dso.h"
+#include "map.h"
+#include "symbol.h"
+#include <internal/lib.h> // page_size
+#include "tests.h"
+#include "debug.h"
+#include "machine.h"
+
+#define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
+
+int test__vmlinux_matches_kallsyms(struct test *test __maybe_unused, int subtest __maybe_unused)
+{
+	int err = -1;
+	struct rb_node *nd;
+	struct symbol *sym;
+	struct map *kallsyms_map, *vmlinux_map, *map;
+	struct machine kallsyms, vmlinux;
+	struct maps *maps = machine__kernel_maps(&vmlinux);
+	u64 mem_start, mem_end;
+	bool header_printed;
+
+	/*
+	 * Step 1:
+	 *
+	 * Init the machines that will hold kernel, modules obtained from
+	 * both vmlinux + .ko files and from /proc/kallsyms split by modules.
+	 */
+	machine__init(&kallsyms, "", HOST_KERNEL_ID);
+	machine__init(&vmlinux, "", HOST_KERNEL_ID);
+
+	/*
+	 * Step 2:
+	 *
+	 * Create the kernel maps for kallsyms and the DSO where we will then
+	 * load /proc/kallsyms. Also create the modules maps from /proc/modules
+	 * and find the .ko files that match them in /lib/modules/`uname -r`/.
+	 */
+	if (machine__create_kernel_maps(&kallsyms) < 0) {
+		pr_debug("machine__create_kernel_maps ");
+		goto out;
+	}
+
+	/*
+	 * Step 3:
+	 *
+	 * Load and split /proc/kallsyms into multiple maps, one per module.
+	 * Do not use kcore, as this test was designed before kcore support
+	 * and has parts that only make sense if using the non-kcore code.
+	 * XXX: extend it to stress the kcorre code as well, hint: the list
+	 * of modules extracted from /proc/kcore, in its current form, can't
+	 * be compacted against the list of modules found in the "vmlinux"
+	 * code and with the one got from /proc/modules from the "kallsyms" code.
+	 */
+	if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
+		pr_debug("dso__load_kallsyms ");
+		goto out;
+	}
+
+	/*
+	 * Step 4:
+	 *
+	 * kallsyms will be internally on demand sorted by name so that we can
+	 * find the reference relocation * symbol, i.e. the symbol we will use
+	 * to see if the running kernel was relocated by checking if it has the
+	 * same value in the vmlinux file we load.
+	 */
+	kallsyms_map = machine__kernel_map(&kallsyms);
+
+	/*
+	 * Step 5:
+	 *
+	 * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
+	 */
+	if (machine__create_kernel_maps(&vmlinux) < 0) {
+		pr_debug("machine__create_kernel_maps ");
+		goto out;
+	}
+
+	vmlinux_map = machine__kernel_map(&vmlinux);
+
+	/*
+	 * Step 6:
+	 *
+	 * Locate a vmlinux file in the vmlinux path that has a buildid that
+	 * matches the one of the running kernel.
+	 *
+	 * While doing that look if we find the ref reloc symbol, if we find it
+	 * we'll have its ref_reloc_symbol.unrelocated_addr and then
+	 * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
+	 * to fixup the symbols.
+	 */
+	if (machine__load_vmlinux_path(&vmlinux) <= 0) {
+		pr_debug("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
+		err = TEST_SKIP;
+		goto out;
+	}
+
+	err = 0;
+	/*
+	 * Step 7:
+	 *
+	 * Now look at the symbols in the vmlinux DSO and check if we find all of them
+	 * in the kallsyms dso. For the ones that are in both, check its names and
+	 * end addresses too.
+	 */
+	map__for_each_symbol(vmlinux_map, sym, nd) {
+		struct symbol *pair, *first_pair;
+
+		sym  = rb_entry(nd, struct symbol, rb_node);
+
+		if (sym->start == sym->end)
+			continue;
+
+		mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
+		mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
+
+		first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
+		pair = first_pair;
+
+		if (pair && UM(pair->start) == mem_start) {
+next_pair:
+			if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
+				/*
+				 * kallsyms don't have the symbol end, so we
+				 * set that by using the next symbol start - 1,
+				 * in some cases we get this up to a page
+				 * wrong, trace_kmalloc when I was developing
+				 * this code was one such example, 2106 bytes
+				 * off the real size. More than that and we
+				 * _really_ have a problem.
+				 */
+				s64 skew = mem_end - UM(pair->end);
+				if (llabs(skew) >= page_size)
+					pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
+						 mem_start, sym->name, mem_end,
+						 UM(pair->end));
+
+				/*
+				 * Do not count this as a failure, because we
+				 * could really find a case where it's not
+				 * possible to get proper function end from
+				 * kallsyms.
+				 */
+				continue;
+			} else {
+				pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
+				if (pair) {
+					if (UM(pair->start) == mem_start)
+						goto next_pair;
+
+					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
+						 mem_start, sym->name, pair->name);
+				} else {
+					pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
+						 mem_start, sym->name, first_pair->name);
+				}
+
+				continue;
+			}
+		} else if (mem_start == kallsyms.vmlinux_map->end) {
+			/*
+			 * Ignore aliases to _etext, i.e. to the end of the kernel text area,
+			 * such as __indirect_thunk_end.
+			 */
+			continue;
+		} else {
+			pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
+				 mem_start, sym->name);
+		}
+
+		err = -1;
+	}
+
+	if (verbose <= 0)
+		goto out;
+
+	header_printed = false;
+
+	maps__for_each_entry(maps, map) {
+		struct map *
+		/*
+		 * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
+		 * the kernel will have the path for the vmlinux file being used,
+		 * so use the short name, less descriptive but the same ("[kernel]" in
+		 * both cases.
+		 */
+		pair = maps__find_by_name(&kallsyms.kmaps, (map->dso->kernel ?
+								map->dso->short_name :
+								map->dso->name));
+		if (pair) {
+			pair->priv = 1;
+		} else {
+			if (!header_printed) {
+				pr_info("WARN: Maps only in vmlinux:\n");
+				header_printed = true;
+			}
+			map__fprintf(map, stderr);
+		}
+	}
+
+	header_printed = false;
+
+	maps__for_each_entry(maps, map) {
+		struct map *pair;
+
+		mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
+		mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
+
+		pair = maps__find(&kallsyms.kmaps, mem_start);
+		if (pair == NULL || pair->priv)
+			continue;
+
+		if (pair->start == mem_start) {
+			if (!header_printed) {
+				pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
+				header_printed = true;
+			}
+
+			pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
+				map->start, map->end, map->pgoff, map->dso->name);
+			if (mem_end != pair->end)
+				pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
+					pair->start, pair->end, pair->pgoff);
+			pr_info(" %s\n", pair->dso->name);
+			pair->priv = 1;
+		}
+	}
+
+	header_printed = false;
+
+	maps = machine__kernel_maps(&kallsyms);
+
+	maps__for_each_entry(maps, map) {
+		if (!map->priv) {
+			if (!header_printed) {
+				pr_info("WARN: Maps only in kallsyms:\n");
+				header_printed = true;
+			}
+			map__fprintf(map, stderr);
+		}
+	}
+out:
+	machine__exit(&kallsyms);
+	machine__exit(&vmlinux);
+	return err;
+}