[RFC][PATCH 06/16] objtool: Add a statistics mode

Peter Zijlstra
2020-03-12T13:52:10Z

Have it print a few numbers which can be used to size the hashtables.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
tools/objtool/builtin-check.c | 3 ++-
tools/objtool/builtin.h | 2 +-
tools/objtool/check.c | 5 +++++
tools/objtool/elf.c | 18 +++++++++++++++++-
4 files changed, 25 insertions(+), 3 deletions(-)

--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -17,7 +17,7 @@
#include "builtin.h"
#include "check.h"

-bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess;
+bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats;

static const char * const check_usage[] = {
"objtool check [<options>] file.o",
@@ -31,6 +31,7 @@ const struct option check_options[] = {
OPT_BOOLEAN('m', "module", &module, "Indicates the object will be part of a kernel module"),
OPT_BOOLEAN('b', "backtrace", &backtrace, "unwind on error"),
OPT_BOOLEAN('a', "uaccess", &uaccess, "enable uaccess checking"),
+ OPT_BOOLEAN('s', "stats", &stats, "print statistics"),
OPT_END(),
};

--- a/tools/objtool/builtin.h
+++ b/tools/objtool/builtin.h
@@ -8,7 +8,7 @@
#include <subcmd/parse-options.h>

extern const struct option check_options[];
-extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess;
+extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats;

extern int cmd_check(int argc, const char **argv);
extern int cmd_orc(int argc, const char **argv);
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -234,6 +234,7 @@ static int decode_instructions(struct ob
struct symbol *func;
unsigned long offset;
struct instruction *insn;
+ unsigned long nr_insns = 0;
int ret;

for_each_sec(file, sec) {
@@ -268,6 +269,7 @@ static int decode_instructions(struct ob
goto err;

hash_add(file->insn_hash, &insn->hash, insn->offset);
+ nr_insns++;
list_add_tail(&insn->list, &file->insn_list);
}

@@ -286,6 +288,9 @@ static int decode_instructions(struct ob
}
}

+ if (stats)
+ printf("nr_insns: %lu\n", nr_insns);
+
return 0;

err:
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -15,6 +15,7 @@
#include <string.h>
#include <unistd.h>
#include <errno.h>
+#include "builtin.h"

#include "elf.h"
#include "warn.h"
@@ -192,6 +193,9 @@ static int read_sections(struct elf *elf
sec->len = sec->sh.sh_size;
}

+ if (stats)
+ printf("nr_sections: %lu\n", (unsigned long)sections_nr);
+
/* sanity check, one more call to elf_nextscn() should return NULL */
if (elf_nextscn(elf->elf, s)) {
WARN("section entry mismatch");
@@ -290,6 +294,9 @@ static int read_symbols(struct elf *elf)
hash_add(elf->symbol_hash, &sym->hash, sym->idx);
}

+ if (stats)
+ printf("nr_symbols: %lu\n", (unsigned long)symbols_nr);
+
/* Create parent/child links for any cold subfunctions */
list_for_each_entry(sec, &elf->sections, list) {
list_for_each_entry(sym, &sec->symbol_list, list) {
@@ -351,6 +358,7 @@ static int read_relas(struct elf *elf)
struct rela *rela;
int i;
unsigned int symndx;
+ unsigned long nr_rela, max_rela = 0, tot_rela = 0;

list_for_each_entry(sec, &elf->sections, list) {
if (sec->sh.sh_type != SHT_RELA)
@@ -365,6 +373,7 @@ static int read_relas(struct elf *elf)

sec->base->rela = sec;

+ nr_rela = 0;
for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
rela = malloc(sizeof(*rela));
if (!rela) {
@@ -392,8 +401,15 @@ static int read_relas(struct elf *elf)

list_add_tail(&rela->list, &sec->rela_list);
hash_add(sec->rela_hash, &rela->hash, rela->offset);
-
+ nr_rela++;
}
+ max_rela = max(max_rela, nr_rela);
+ tot_rela += nr_rela;
+ }
+
+ if (stats) {
+ printf("max_rela: %lu\n", max_rela);
+ printf("tot_rela: %lu\n", tot_rela);
}

return 0;