linux-kernel - [PATCH 5.16 115/121] x86/module: Fix the paravirt vs alternative order

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Message-Id: <20220314112747.322871288@linuxfoundation.org>
Date:   Mon, 14 Mar 2022 12:54:58 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Borislav Petkov <bp@...e.de>, Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH 5.16 115/121] x86/module: Fix the paravirt vs alternative order

From: Peter Zijlstra <peterz@...radead.org>

commit 5adf349439d29f92467e864f728dfc23180f3ef9 upstream.

Ever since commit

  4e6292114c74 ("x86/paravirt: Add new features for paravirt patching")

there is an ordering dependency between patching paravirt ops and
patching alternatives, the module loader still violates this.

Fixes: 4e6292114c74 ("x86/paravirt: Add new features for paravirt patching")
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Miroslav Benes <mbenes@...e.cz>
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20220303112825.068773913@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/module.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -273,6 +273,14 @@ int module_finalize(const Elf_Ehdr *hdr,
 			retpolines = s;
 	}
 
+	/*
+	 * See alternative_instructions() for the ordering rules between the
+	 * various patching types.
+	 */
+	if (para) {
+		void *pseg = (void *)para->sh_addr;
+		apply_paravirt(pseg, pseg + para->sh_size);
+	}
 	if (retpolines) {
 		void *rseg = (void *)retpolines->sh_addr;
 		apply_retpolines(rseg, rseg + retpolines->sh_size);
@@ -290,11 +298,6 @@ int module_finalize(const Elf_Ehdr *hdr,
 					    tseg, tseg + text->sh_size);
 	}
 
-	if (para) {
-		void *pseg = (void *)para->sh_addr;
-		apply_paravirt(pseg, pseg + para->sh_size);
-	}
-
 	/* make jump label nops */
 	jump_label_apply_nops(me);