From: Julien Thierry <jthierry@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: jpoimboe@redhat.com, peterz@infradead.org, mbenes@suse.cz,
raphael.gault@arm.com, benh@kernel.crashing.org,
Julien Thierry <jthierry@redhat.com>
Subject: [PATCH 2/3] objtool: check: Support addition to set CFA base
Date: Tue, 15 Sep 2020 09:12:03 +0100 [thread overview]
Message-ID: <20200915081204.9204-3-jthierry@redhat.com> (raw)
In-Reply-To: <20200915081204.9204-1-jthierry@redhat.com>
Instead of "mov SP, BP", a compiler could simply set BP
to SP + constant. Handle changing the CFA base in such cases.
Signed-off-by: Julien Thierry <jthierry@redhat.com>
---
tools/objtool/check.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 7db6761d28c2..f45991c2db41 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1898,6 +1898,19 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
break;
}
+ if (!cfi->drap && op->src.reg == CFI_SP &&
+ op->dest.reg == CFI_BP && cfa->base == CFI_SP &&
+ check_reg_frame_pos(®s[CFI_BP],
+ -cfa->offset + op->src.offset + CFA_SIZE,
+ CFA_BP_OFFSET)) {
+
+ /* lea disp(%rsp), %rbp */
+ cfa->base = CFI_BP;
+ cfa->offset -= op->src.offset;
+ cfi->bp_scratch = false;
+ break;
+ }
+
if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
/* drap: lea disp(%rsp), %drap */
--
2.21.3
next prev parent reply other threads:[~2020-09-15 8:25 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 8:12 [PATCH 0/3] objtool: Extend CFA updating/checking Julien Thierry
2020-09-15 8:12 ` [PATCH 1/3] objtool: check: Fully validate the stack frame Julien Thierry
2020-09-18 20:56 ` Josh Poimboeuf
2020-09-21 10:31 ` Julien Thierry
2020-09-21 15:03 ` Josh Poimboeuf
2020-09-15 8:12 ` Julien Thierry [this message]
2020-09-18 21:09 ` [PATCH 2/3] objtool: check: Support addition to set CFA base Josh Poimboeuf
2020-09-15 8:12 ` [PATCH 3/3] objtool: check: Make SP memory operation match PUSH/POP semantics Julien Thierry
2020-09-18 21:43 ` Josh Poimboeuf
2020-09-21 10:31 ` Julien Thierry
2020-09-21 15:12 ` Josh Poimboeuf
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