1 files changed, 230 insertions, 0 deletions

diff --git a/tools/perf/tests/vmlinux-kallsyms.c b/tools/perf/tests/vmlinux-kallsyms.c
new file mode 100644
index 00000000000..0d1cdbee2f5
--- /dev/null
+++ b/tools/perf/tests/vmlinux-kallsyms.c
@@ -0,0 +1,230 @@
+#include <linux/compiler.h>
+#include <linux/rbtree.h>
+#include <string.h>
+#include "map.h"
+#include "symbol.h"
+#include "util.h"
+#include "tests.h"
+#include "debug.h"
+#include "machine.h"
+
+static int vmlinux_matches_kallsyms_filter(struct map *map __maybe_unused,
+                                           struct symbol *sym)
+{
+        bool *visited = symbol__priv(sym);
+        *visited = true;
+        return 0;
+}
+
+int test__vmlinux_matches_kallsyms(void)
+{
+        int err = -1;
+        struct rb_node *nd;
+        struct symbol *sym;
+        struct map *kallsyms_map, *vmlinux_map;
+        struct machine kallsyms, vmlinux;
+        enum map_type type = MAP__FUNCTION;
+        struct ref_reloc_sym ref_reloc_sym = { .name = "_stext", };
+
+        /*
+         * 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 ");
+                return -1;
+        }
+
+        /*
+         * Step 3:
+         *
+         * Load and split /proc/kallsyms into multiple maps, one per module.
+         */
+        if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms", type, NULL) <= 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, type);
+
+        sym = map__find_symbol_by_name(kallsyms_map, ref_reloc_sym.name, NULL);
+        if (sym == NULL) {
+                pr_debug("dso__find_symbol_by_name ");
+                goto out;
+        }
+
+        ref_reloc_sym.addr = sym->start;
+
+        /*
+         * 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, type);
+        map__kmap(vmlinux_map)->ref_reloc_sym = &ref_reloc_sym;
+
+        /*
+         * 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, type,
+                                       vmlinux_matches_kallsyms_filter) <= 0) {
+                pr_debug("machine__load_vmlinux_path ");
+                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.
+         */
+        for (nd = rb_first(&vmlinux_map->dso->symbols[type]); nd; nd = rb_next(nd)) {
+                struct symbol *pair, *first_pair;
+                bool backwards = true;
+
+                sym  = rb_entry(nd, struct symbol, rb_node);
+
+                if (sym->start == sym->end)
+                        continue;
+
+                first_pair = machine__find_kernel_symbol(&kallsyms, type, sym->start, NULL, NULL);
+                pair = first_pair;
+
+                if (pair && pair->start == sym->start) {
+next_pair:
+                        if (strcmp(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 = sym->end - pair->end;
+                                if (llabs(skew) < page_size)
+                                        continue;
+
+                                pr_debug("%#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
+                                         sym->start, sym->name, sym->end, pair->end);
+                        } else {
+                                struct rb_node *nnd;
+detour:
+                                nnd = backwards ? rb_prev(&pair->rb_node) :
+                                                  rb_next(&pair->rb_node);
+                                if (nnd) {
+                                        struct symbol *next = rb_entry(nnd, struct symbol, rb_node);
+
+                                        if (next->start == sym->start) {
+                                                pair = next;
+                                                goto next_pair;
+                                        }
+                                }
+
+                                if (backwards) {
+                                        backwards = false;
+                                        pair = first_pair;
+                                        goto detour;
+                                }
+
+                                pr_debug("%#" PRIx64 ": diff name v: %s k: %s\n",
+                                         sym->start, sym->name, pair->name);
+                        }
+                } else
+                        pr_debug("%#" PRIx64 ": %s not on kallsyms\n", sym->start, sym->name);
+
+                err = -1;
+        }
+
+        if (!verbose)
+                goto out;
+
+        pr_info("Maps only in vmlinux:\n");
+
+        for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
+                struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
+                /*
+                 * 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 = map_groups__find_by_name(&kallsyms.kmaps, type,
+                                                (pos->dso->kernel ?
+                                                        pos->dso->short_name :
+                                                        pos->dso->name));
+                if (pair)
+                        pair->priv = 1;
+                else
+                        map__fprintf(pos, stderr);
+        }
+
+        pr_info("Maps in vmlinux with a different name in kallsyms:\n");
+
+        for (nd = rb_first(&vmlinux.kmaps.maps[type]); nd; nd = rb_next(nd)) {
+                struct map *pos = rb_entry(nd, struct map, rb_node), *pair;
+
+                pair = map_groups__find(&kallsyms.kmaps, type, pos->start);
+                if (pair == NULL || pair->priv)
+                        continue;
+
+                if (pair->start == pos->start) {
+                        pair->priv = 1;
+                        pr_info(" %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
+                                pos->start, pos->end, pos->pgoff, pos->dso->name);
+                        if (pos->pgoff != pair->pgoff || pos->end != pair->end)
+                                pr_info(": \n*%" PRIx64 "-%" PRIx64 " %" PRIx64 "",
+                                        pair->start, pair->end, pair->pgoff);
+                        pr_info(" %s\n", pair->dso->name);
+                        pair->priv = 1;
+                }
+        }
+
+        pr_info("Maps only in kallsyms:\n");
+
+        for (nd = rb_first(&kallsyms.kmaps.maps[type]);
+             nd; nd = rb_next(nd)) {
+                struct map *pos = rb_entry(nd, struct map, rb_node);
+
+                if (!pos->priv)
+                        map__fprintf(pos, stderr);
+        }
+out:
+        return err;
+}