[tip: objtool/core] objtool: Also consider .entry.text as noinstr

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     0cc9ac8db0b447922d9af77916cd7941fc784b64
Gitweb:        https://git.kernel.org/tip/0cc9ac8db0b447922d9af77916cd7941fc784b64
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Wed, 25 Mar 2020 17:18:17 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 22 Apr 2020 10:53:51 +02:00

objtool: Also consider .entry.text as noinstr

Consider all of .entry.text as noinstr. This gets us coverage across
the PTI boundary. While we could add everything .noinstr.text into
.entry.text that would bloat the amount of code in the user mapping.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
Reviewed-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200416115119.525037514@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 tools/objtool/check.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0d9f9cf..f2a8427 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -266,7 +266,8 @@ static int decode_instructions(struct objtool_file *file)
 		    strncmp(sec->name, ".discard.", 9))
 			sec->text = true;
 
-		if (!strcmp(sec->name, ".noinstr.text"))
+		if (!strcmp(sec->name, ".noinstr.text") ||
+		    !strcmp(sec->name, ".entry.text"))
 			sec->noinstr = true;
 
 		for (offset = 0; offset < sec->len; offset += insn->len) {
@@ -2071,7 +2072,7 @@ static inline const char *call_dest_name(struct instruction *insn)
 static int validate_call(struct instruction *insn, struct insn_state *state)
 {
 	if (state->noinstr && state->instr <= 0 &&
-	    (!insn->call_dest || insn->call_dest->sec != insn->sec)) {
+	    (!insn->call_dest || !insn->call_dest->sec->noinstr)) {
 		WARN_FUNC("call to %s() leaves .noinstr.text section",
 				insn->sec, insn->offset, call_dest_name(insn));
 		return 1;
@@ -2558,11 +2559,16 @@ static int validate_vmlinux_functions(struct objtool_file *file)
 	int warnings = 0;
 
 	sec = find_section_by_name(file->elf, ".noinstr.text");
-	if (!sec)
-		return 0;
+	if (sec) {
+		warnings += validate_section(file, sec);
+		warnings += validate_unwind_hints(file, sec);
+	}
 
-	warnings += validate_section(file, sec);
-	warnings += validate_unwind_hints(file, sec);
+	sec = find_section_by_name(file->elf, ".entry.text");
+	if (sec) {
+		warnings += validate_section(file, sec);
+		warnings += validate_unwind_hints(file, sec);
+	}
 
 	return warnings;
 }