From: Julien Thierry <jthierry@redhat.com>
Date: Wed, 14 Oct 2020 07:38:02 +0000 (+0100)
Subject: objtool: Make SP memory operation match PUSH/POP semantics
X-Git-Tag: howlett/maple/20220722_2~3692^2~30
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=201ef5a974e24112953b74cc9f33dcfc4cbcc1cb;p=users%2Fjedix%2Flinux-maple.git

objtool: Make SP memory operation match PUSH/POP semantics

Architectures without PUSH/POP instructions will always access the stack
though memory operations (SRC/DEST_INDIRECT). Make those operations have
the same effect on the CFA as PUSH/POP, with no stack pointer
modification.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 00d00f904536..270adc38d896 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2065,6 +2065,14 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
 			break;
 
 		case OP_SRC_REG_INDIRECT:
+			if (!cfi->drap && op->dest.reg == cfa->base &&
+			    op->dest.reg == CFI_BP) {
+
+				/* mov disp(%rsp), %rbp */
+				cfa->base = CFI_SP;
+				cfa->offset = cfi->stack_size;
+			}
+
 			if (cfi->drap && op->src.reg == CFI_BP &&
 			    op->src.offset == cfi->drap_offset) {
 
@@ -2086,6 +2094,12 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
 				/* mov disp(%rbp), %reg */
 				/* mov disp(%rsp), %reg */
 				restore_reg(cfi, op->dest.reg);
+
+			} else if (op->src.reg == CFI_SP &&
+				   op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
+
+				/* mov disp(%rsp), %reg */
+				restore_reg(cfi, op->dest.reg);
 			}
 
 			break;
@@ -2163,6 +2177,12 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
 			/* mov reg, disp(%rsp) */
 			save_reg(cfi, op->src.reg, CFI_CFA,
 				 op->dest.offset - cfi->cfa.offset);
+
+		} else if (op->dest.reg == CFI_SP) {
+
+			/* mov reg, disp(%rsp) */
+			save_reg(cfi, op->src.reg, CFI_CFA,
+				 op->dest.offset - cfi->stack_size);
 		}
 
 		break;