lkml.org 
[lkml]   [2023]   [Aug]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: x86/urgent] objtool/x86: Fixup frame-pointer vs rethunk
The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: dbf46008775516f7f25c95b7760041c286299783
Gitweb: https://git.kernel.org/tip/dbf46008775516f7f25c95b7760041c286299783
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Wed, 16 Aug 2023 13:59:21 +02:00
Committer: Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Thu, 17 Aug 2023 00:44:35 +02:00

objtool/x86: Fixup frame-pointer vs rethunk

For stack-validation of a frame-pointer build, objtool validates that
every CALL instruction is preceded by a frame-setup. The new SRSO
return thunks violate this with their RSB stuffing trickery.

Extend the __fentry__ exception to also cover the embedded_insn case
used for this. This cures:

vmlinux.o: warning: objtool: srso_untrain_ret+0xd: call without frame pointer save/setup

Fixes: 4ae68b26c3ab ("objtool/x86: Fix SRSO mess")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20230816115921.GH980931@hirez.programming.kicks-ass.net
---
tools/objtool/check.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 7a9aaf4..1384090 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2650,12 +2650,17 @@ static int decode_sections(struct objtool_file *file)
return 0;
}

-static bool is_fentry_call(struct instruction *insn)
+static bool is_special_call(struct instruction *insn)
{
- if (insn->type == INSN_CALL &&
- insn_call_dest(insn) &&
- insn_call_dest(insn)->fentry)
- return true;
+ if (insn->type == INSN_CALL) {
+ struct symbol *dest = insn_call_dest(insn);
+
+ if (!dest)
+ return false;
+
+ if (dest->fentry || dest->embedded_insn)
+ return true;
+ }

return false;
}
@@ -3656,7 +3661,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
if (ret)
return ret;

- if (opts.stackval && func && !is_fentry_call(insn) &&
+ if (opts.stackval && func && !is_special_call(insn) &&
!has_valid_stack_frame(&state)) {
WARN_INSN(insn, "call without frame pointer save/setup");
return 1;
\
 
 \ /
  Last update: 2023-08-17 10:41    [W:0.149 / U:5.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site