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authorAdrian Hunter <adrian.hunter@intel.com>2013-08-07 14:38:47 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2013-08-07 17:35:31 -0300
commit39b12f7812710e9a5896805d96812b3ede7491e8 (patch)
tree86e56aa9aeebb18872a2ab256839978a79d2c4ad /tools/perf/util/symbol-elf.c
parent5b7ba82a75915e739709d0ace4bb559cb280db09 (diff)
perf tools: Make it possible to read object code from vmlinux
The new "object code reading" test shows that it is not possible to read object code from vmlinux. That is because the mappings do not map to the dso. This patch fixes that. A side-effect of changing the kernel map is that the "reloc" offset must be taken into account. As a result of that separate map functions for relocation are no longer needed. Also fixing up the maps to match the symbols no longer makes sense and so is not done. The vmlinux dso data_type is now set to either DSO_BINARY_TYPE__VMLINUX or DSO_BINARY_TYPE__GUEST_VMLINUX as approprite, which enables the correct file name to be determined by dso__binary_type_file(). This patch breaks the "vmlinux symtab matches kallsyms" test. That is fixed in a following patch. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lkml.kernel.org/r/1375875537-4509-4-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/symbol-elf.c')
-rw-r--r--tools/perf/util/symbol-elf.c100
1 files changed, 91 insertions, 9 deletions
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 4b12bf85032..ed6f443a3e1 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -603,7 +603,7 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
".gnu.prelink_undo",
NULL) != NULL);
} else {
- ss->adjust_symbols = 0;
+ ss->adjust_symbols = ehdr.e_type == ET_EXEC;
}
ss->name = strdup(name);
@@ -624,6 +624,37 @@ out_close:
return err;
}
+/**
+ * ref_reloc_sym_not_found - has kernel relocation symbol been found.
+ * @kmap: kernel maps and relocation reference symbol
+ *
+ * This function returns %true if we are dealing with the kernel maps and the
+ * relocation reference symbol has not yet been found. Otherwise %false is
+ * returned.
+ */
+static bool ref_reloc_sym_not_found(struct kmap *kmap)
+{
+ return kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
+ !kmap->ref_reloc_sym->unrelocated_addr;
+}
+
+/**
+ * ref_reloc - kernel relocation offset.
+ * @kmap: kernel maps and relocation reference symbol
+ *
+ * This function returns the offset of kernel addresses as determined by using
+ * the relocation reference symbol i.e. if the kernel has not been relocated
+ * then the return value is zero.
+ */
+static u64 ref_reloc(struct kmap *kmap)
+{
+ if (kmap && kmap->ref_reloc_sym &&
+ kmap->ref_reloc_sym->unrelocated_addr)
+ return kmap->ref_reloc_sym->addr -
+ kmap->ref_reloc_sym->unrelocated_addr;
+ return 0;
+}
+
int dso__load_sym(struct dso *dso, struct map *map,
struct symsrc *syms_ss, struct symsrc *runtime_ss,
symbol_filter_t filter, int kmodule)
@@ -642,6 +673,7 @@ int dso__load_sym(struct dso *dso, struct map *map,
Elf_Scn *sec, *sec_strndx;
Elf *elf;
int nr = 0;
+ bool remap_kernel = false, adjust_kernel_syms = false;
dso->symtab_type = syms_ss->type;
@@ -681,7 +713,31 @@ int dso__load_sym(struct dso *dso, struct map *map,
nr_syms = shdr.sh_size / shdr.sh_entsize;
memset(&sym, 0, sizeof(sym));
- dso->adjust_symbols = runtime_ss->adjust_symbols;
+
+ /*
+ * The kernel relocation symbol is needed in advance in order to adjust
+ * kernel maps correctly.
+ */
+ if (ref_reloc_sym_not_found(kmap)) {
+ elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
+ const char *elf_name = elf_sym__name(&sym, symstrs);
+
+ if (strcmp(elf_name, kmap->ref_reloc_sym->name))
+ continue;
+ kmap->ref_reloc_sym->unrelocated_addr = sym.st_value;
+ break;
+ }
+ }
+
+ dso->adjust_symbols = runtime_ss->adjust_symbols || ref_reloc(kmap);
+ /*
+ * Initial kernel and module mappings do not map to the dso. For
+ * function mappings, flag the fixups.
+ */
+ if (map->type == MAP__FUNCTION && (dso->kernel || kmodule)) {
+ remap_kernel = true;
+ adjust_kernel_syms = dso->adjust_symbols;
+ }
elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
struct symbol *f;
const char *elf_name = elf_sym__name(&sym, symstrs);
@@ -690,10 +746,6 @@ int dso__load_sym(struct dso *dso, struct map *map,
const char *section_name;
bool used_opd = false;
- if (kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
- strcmp(elf_name, kmap->ref_reloc_sym->name) == 0)
- kmap->ref_reloc_sym->unrelocated_addr = sym.st_value;
-
if (!is_label && !elf_sym__is_a(&sym, map->type))
continue;
@@ -745,15 +797,37 @@ int dso__load_sym(struct dso *dso, struct map *map,
(sym.st_value & 1))
--sym.st_value;
- if (dso->kernel != DSO_TYPE_USER || kmodule) {
+ if (dso->kernel || kmodule) {
char dso_name[PATH_MAX];
+ /* Adjust symbol to map to file offset */
+ if (adjust_kernel_syms)
+ sym.st_value -= shdr.sh_addr - shdr.sh_offset;
+
if (strcmp(section_name,
(curr_dso->short_name +
dso->short_name_len)) == 0)
goto new_symbol;
if (strcmp(section_name, ".text") == 0) {
+ /*
+ * The initial kernel mapping is based on
+ * kallsyms and identity maps. Overwrite it to
+ * map to the kernel dso.
+ */
+ if (remap_kernel && dso->kernel) {
+ remap_kernel = false;
+ map->start = shdr.sh_addr +
+ ref_reloc(kmap);
+ map->end = map->start + shdr.sh_size;
+ map->pgoff = shdr.sh_offset;
+ map->map_ip = map__map_ip;
+ map->unmap_ip = map__unmap_ip;
+ /* Ensure maps are correctly ordered */
+ map_groups__remove(kmap->kmaps, map);
+ map_groups__insert(kmap->kmaps, map);
+ }
+
curr_map = map;
curr_dso = dso;
goto new_symbol;
@@ -781,8 +855,16 @@ int dso__load_sym(struct dso *dso, struct map *map,
dso__delete(curr_dso);
goto out_elf_end;
}
- curr_map->map_ip = identity__map_ip;
- curr_map->unmap_ip = identity__map_ip;
+ if (adjust_kernel_syms) {
+ curr_map->start = shdr.sh_addr +
+ ref_reloc(kmap);
+ curr_map->end = curr_map->start +
+ shdr.sh_size;
+ curr_map->pgoff = shdr.sh_offset;
+ } else {
+ curr_map->map_ip = identity__map_ip;
+ curr_map->unmap_ip = identity__map_ip;
+ }
curr_dso->symtab_type = dso->symtab_type;
map_groups__insert(kmap->kmaps, curr_map);
dsos__add(&dso->node, curr_dso);