linux-kernel - [RFC 23/31] objtool: Handle __pa

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Message-ID: <9b5ebea4361ec1a5471b6b2e86d6657b5685c72d.1725334260.git.jpoimboe@kernel.org>
Date: Mon,  2 Sep 2024 21:00:06 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: live-patching@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	x86@...nel.org,
	Miroslav Benes <mbenes@...e.cz>,
	Petr Mladek <pmladek@...e.com>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Song Liu <song@...nel.org>
Subject: [RFC 23/31] objtool: Handle __pa_symbol() relocations

A relocation created by __pa_symbol() has a large addend referring to a
physical address.  Convert it to back its virtual form before
calculating the addend.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/arch/x86/decode.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index afebd67d9b9d..5468fd15f380 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -67,6 +67,17 @@ bool arch_callee_saved_reg(unsigned char reg)
 	}
 }
 
+/* undo the effects of __pa_symbol() if necessary */
+static unsigned long phys_to_virt(unsigned long pa)
+{
+	s64 va = pa;
+
+	if (va > 0)
+		va &= ~(0x80000000);
+
+	return va;
+}
+
 s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 {
 	s64 addend = reloc_addend(reloc);
@@ -80,7 +91,7 @@ s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 		break;
 	}
 
-	return addend;
+	return phys_to_virt(addend);
 }
 
 unsigned long arch_jump_destination(struct instruction *insn)
-- 
2.45.2