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Subject[tip: x86/core] objtool: Read the NOENDBR annotation
The following commit has been merged into the x86/core branch of tip:

Commit-ID: 51727f8e4a1ae15770ac30f05a90536c4aa3b2d8
Gitweb: https://git.kernel.org/tip/51727f8e4a1ae15770ac30f05a90536c4aa3b2d8
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Tue, 08 Mar 2022 16:30:52 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 08 Mar 2022 23:53:38 +01:00

objtool: Read the NOENDBR annotation

Read the new NOENDBR annotation. While there, attempt to not bloat
struct instruction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154319.586815435@infradead.org
---
tools/objtool/check.c | 27 ++++++++++++++++++++++++++-
tools/objtool/include/objtool/check.h | 13 ++++++++++---
2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index aee6246..3f28ca4 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1865,6 +1865,29 @@ static int read_unwind_hints(struct objtool_file *file)
return 0;
}

+static int read_noendbr_hints(struct objtool_file *file)
+{
+ struct section *sec;
+ struct instruction *insn;
+ struct reloc *reloc;
+
+ sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
+ if (!sec)
+ return 0;
+
+ list_for_each_entry(reloc, &sec->reloc_list, list) {
+ insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
+ if (!insn) {
+ WARN("bad .discard.noendbr entry");
+ return -1;
+ }
+
+ insn->noendbr = 1;
+ }
+
+ return 0;
+}
+
static int read_retpoline_hints(struct objtool_file *file)
{
struct section *sec;
@@ -2098,6 +2121,10 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;

+ ret = read_noendbr_hints(file);
+ if (ret)
+ return ret;
+
/*
* Must be before add_{jump_call}_destination.
*/
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 6cfff07..f10d737 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -45,11 +45,18 @@ struct instruction {
unsigned int len;
enum insn_type type;
unsigned long immediate;
- bool dead_end, ignore, ignore_alts;
- bool hint;
- bool retpoline_safe;
+
+ u8 dead_end : 1,
+ ignore : 1,
+ ignore_alts : 1,
+ hint : 1,
+ retpoline_safe : 1,
+ noendbr : 1;
+ /* 2 bit hole */
s8 instr;
u8 visited;
+ /* u8 hole */
+
struct alt_group *alt_group;
struct symbol *call_dest;
struct instruction *jump_dest;
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