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authorSami Tolvanen <samitolvanen@google.com>2020-04-21 15:08:43 -0700
committerPeter Zijlstra <peterz@infradead.org>2020-05-15 10:35:13 +0200
commit6b5dd716da8fc3aba65e6b7d992dea0cee2f9528 (patch)
tree2e5c1e4a8ad1c0d6619a30a476b76bc28de29cec /tools/objtool/check.c
parent28fe1d7bf89f8ed5be70b98a33932dbaf99345dd (diff)
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objtool: optimize add_dead_ends for split sections
Instead of iterating through all instructions to find the last instruction each time .rela.discard.(un)reachable points beyond the section, use find_insn to locate the last instruction by looking at the last bytes of the section instead. Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200421220843.188260-3-samitolvanen@google.com
Diffstat (limited to 'tools/objtool/check.c')
-rw-r--r--tools/objtool/check.c36
1 files changed, 17 insertions, 19 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 196a55101f3c..6b2b458a5b0e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -322,6 +322,19 @@ err:
return ret;
}
+static struct instruction *find_last_insn(struct objtool_file *file,
+ struct section *sec)
+{
+ struct instruction *insn = NULL;
+ unsigned int offset;
+ unsigned int end = (sec->len > 10) ? sec->len - 10 : 0;
+
+ for (offset = sec->len - 1; offset >= end && !insn; offset--)
+ insn = find_insn(file, sec, offset);
+
+ return insn;
+}
+
/*
* Mark "ud2" instructions and manually annotated dead ends.
*/
@@ -330,7 +343,6 @@ 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
@@ -356,15 +368,8 @@ 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;
- }
- }
-
- if (!found) {
+ insn = find_last_insn(file, rela->sym->sec);
+ if (!insn) {
WARN("can't find unreachable insn at %s+0x%x",
rela->sym->sec->name, rela->addend);
return -1;
@@ -398,15 +403,8 @@ reachable:
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;
- }
- }
-
- if (!found) {
+ insn = find_last_insn(file, rela->sym->sec);
+ if (!insn) {
WARN("can't find reachable insn at %s+0x%x",
rela->sym->sec->name, rela->addend);
return -1;