From: Sami Tolvanen <samitolvanen@google.com>
To: Josh Poimboeuf <jpoimboe@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org,
Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH 3/3] objtool: optimize add_dead_ends for split sections
Date: Tue, 21 Apr 2020 11:07:24 -0700 [thread overview]
Message-ID: <20200421180724.245410-4-samitolvanen@google.com> (raw)
In-Reply-To: <20200421180724.245410-1-samitolvanen@google.com>
When running objtool on vmlinux.o compiled with -ffunction-sections,
.rela.discard.(un)reachable often contains relocations that point to
a different section. Instead of iterating through the list of all
instructions each time, store a pointer to the last instruction of
each section when decoding instructions.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
tools/objtool/check.c | 43 ++++++++++++++++++++++++++-----------------
tools/objtool/check.h | 4 ++++
tools/objtool/elf.h | 1 +
3 files changed, 31 insertions(+), 17 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4770fb07b365..7d4104de0a5e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -237,6 +237,7 @@ static void clear_insn_state(struct insn_state *state)
static int decode_instructions(struct objtool_file *file)
{
struct section *sec;
+ struct section_info *sec_info = NULL;
struct symbol *func;
unsigned long offset;
struct instruction *insn;
@@ -253,6 +254,8 @@ static int decode_instructions(struct objtool_file *file)
strncmp(sec->name, ".discard.", 9))
sec->text = true;
+ insn = NULL;
+
for (offset = 0; offset < sec->len; offset += insn->len) {
insn = malloc(sizeof(*insn));
if (!insn) {
@@ -279,6 +282,17 @@ static int decode_instructions(struct objtool_file *file)
nr_insns++;
}
+ if (insn) {
+ sec_info = malloc(sizeof(*sec_info));
+ if (!sec_info) {
+ WARN("malloc failed");
+ return -1;
+ }
+
+ sec_info->last_insn = insn;
+ sec->section_info = sec_info;
+ }
+
list_for_each_entry(func, &sec->symbol_list, list) {
if (func->type != STT_FUNC || func->alias != func)
continue;
@@ -312,7 +326,6 @@ static int add_dead_ends(struct objtool_file *file)
struct section *sec;
struct rela *rela;
struct instruction *insn;
- bool found;
/*
* By default, "ud2" is a dead end unless otherwise annotated, because
@@ -338,15 +351,13 @@ static int add_dead_ends(struct objtool_file *file)
if (insn)
insn = list_prev_entry(insn, list);
else if (rela->addend == rela->sym->sec->len) {
- found = false;
- list_for_each_entry_reverse(insn, &file->insn_list, list) {
- if (insn->sec == rela->sym->sec) {
- found = true;
- break;
- }
- }
+ struct section_info *sec_info = (struct section_info *)
+ rela->sym->sec->section_info;
+
+ if (sec_info)
+ insn = sec_info->last_insn;
- if (!found) {
+ if (!insn) {
WARN("can't find unreachable insn at %s+0x%x",
rela->sym->sec->name, rela->addend);
return -1;
@@ -380,15 +391,13 @@ static int add_dead_ends(struct objtool_file *file)
if (insn)
insn = list_prev_entry(insn, list);
else if (rela->addend == rela->sym->sec->len) {
- found = false;
- list_for_each_entry_reverse(insn, &file->insn_list, list) {
- if (insn->sec == rela->sym->sec) {
- found = true;
- break;
- }
- }
+ struct section_info *sec_info = (struct section_info *)
+ rela->sym->sec->section_info;
+
+ if (sec_info)
+ insn = sec_info->last_insn;
- if (!found) {
+ if (!insn) {
WARN("can't find reachable insn at %s+0x%x",
rela->sym->sec->name, rela->addend);
return -1;
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index bc78eca7982e..353677ec85d4 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -47,6 +47,10 @@ struct instruction {
struct orc_entry orc;
};
+struct section_info {
+ struct instruction *last_insn;
+};
+
struct objtool_file {
struct elf *elf;
struct list_head insn_list;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index ebbb10c61e24..98f2b41d18e4 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -40,6 +40,7 @@ struct section {
int idx;
unsigned int len;
bool changed, text, rodata;
+ void *section_info;
};
struct symbol {
--
2.26.1.301.g55bc3eb7cb9-goog
next prev parent reply other threads:[~2020-04-21 18:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-21 18:07 [PATCH 0/3] objtool: add support for >64k sections Sami Tolvanen
2020-04-21 18:07 ` [PATCH 1/3] objtool: use gelf_getsymshndx to handle " Sami Tolvanen
2020-04-21 20:11 ` Kees Cook
2020-04-21 18:07 ` [PATCH 2/3] objtool: optimize insn_hash for split sections Sami Tolvanen
2020-04-21 19:47 ` Peter Zijlstra
2020-04-21 20:13 ` Kees Cook
2020-04-21 20:20 ` Sami Tolvanen
2020-04-21 18:07 ` Sami Tolvanen [this message]
2020-04-21 20:13 ` [PATCH 3/3] objtool: optimize add_dead_ends " Josh Poimboeuf
2020-04-21 20:17 ` Kees Cook
2020-04-21 22:02 ` Sami Tolvanen
2020-04-21 20:14 ` Kees Cook
2020-04-21 20:11 ` [PATCH 0/3] objtool: add support for >64k sections Kees Cook
2020-04-21 22:08 ` [PATCH v2 0/2] " Sami Tolvanen
2020-04-21 22:08 ` [PATCH v2 1/2] objtool: use gelf_getsymshndx to handle " Sami Tolvanen
2020-05-15 17:22 ` [tip: objtool/core] " tip-bot2 for Sami Tolvanen
2020-04-21 22:08 ` [PATCH v2 2/2] objtool: optimize add_dead_ends for split sections Sami Tolvanen
2020-04-21 23:43 ` Kees Cook
2020-05-15 17:22 ` [tip: objtool/core] " tip-bot2 for Sami Tolvanen
2020-04-21 23:52 ` [PATCH v2 0/2] objtool: add support for >64k sections Josh Poimboeuf
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