linux-kernel - [tip:x86/mm] x86/jump_label: Use text_poke

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Message-ID: <tip-1fd8de46d01d95f875c12684a6a03559831e8b4c@git.kernel.org>
Date:   Tue, 30 Apr 2019 04:15:55 -0700
From:   tip-bot for Nadav Amit <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     riel@...riel.com, akpm@...ux-foundation.org,
        kernel-hardening@...ts.openwall.com, torvalds@...ux-foundation.org,
        hpa@...or.com, mingo@...nel.org, linux-kernel@...r.kernel.org,
        dave.hansen@...el.com, kristen@...ux.intel.com, bp@...en8.de,
        tglx@...utronix.de, linux_dti@...oud.com, will.deacon@....com,
        keescook@...omium.org, deneen.t.dock@...el.com, namit@...are.com,
        mhiramat@...nel.org, rick.p.edgecombe@...el.com,
        ard.biesheuvel@...aro.org, peterz@...radead.org, luto@...nel.org
Subject: [tip:x86/mm] x86/jump_label: Use text_poke_early() during early
 init

Commit-ID:  1fd8de46d01d95f875c12684a6a03559831e8b4c
Gitweb:     https://git.kernel.org/tip/1fd8de46d01d95f875c12684a6a03559831e8b4c
Author:     Nadav Amit <namit@...are.com>
AuthorDate: Thu, 25 Apr 2019 17:11:22 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 30 Apr 2019 12:37:49 +0200

x86/jump_label: Use text_poke_early() during early init

There is no apparent reason not to use text_poke_early() during
early-init, since no patching of code that might be on the stack is done
and only a single core is running.

This is required for the next patches that would set a temporary mm for
text poking, and this mm is only initialized after some static-keys are
enabled/disabled.

Signed-off-by: Nadav Amit <namit@...are.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: <akpm@...ux-foundation.org>
Cc: <ard.biesheuvel@...aro.org>
Cc: <deneen.t.dock@...el.com>
Cc: <kernel-hardening@...ts.openwall.com>
Cc: <kristen@...ux.intel.com>
Cc: <linux_dti@...oud.com>
Cc: <will.deacon@....com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-3-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/jump_label.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index f99bd26bd3f1..e7d8c636b228 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -50,7 +50,12 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
 	jmp.offset = jump_entry_target(entry) -
 		     (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
 
-	if (early_boot_irqs_disabled)
+	/*
+	 * As long as only a single processor is running and the code is still
+	 * not marked as RO, text_poke_early() can be used; Checking that
+	 * system_state is SYSTEM_BOOTING guarantees it.
+	 */
+	if (system_state == SYSTEM_BOOTING)
 		poker = text_poke_early;
 
 	if (type == JUMP_LABEL_JMP) {