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Message-ID: <20190426001143.4983-3-namit@vmware.com>
Date: Thu, 25 Apr 2019 17:11:22 -0700
From: Nadav Amit <namit@...are.com>
To: Peter Zijlstra <peterz@...radead.org>, Borislav Petkov <bp@...en8.de>,
Andy Lutomirski <luto@...nel.org>, Ingo Molnar <mingo@...hat.com>
CC: <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <hpa@...or.com>, Thomas
Gleixner <tglx@...utronix.de>, Nadav Amit <nadav.amit@...il.com>, Dave Hansen
<dave.hansen@...ux.intel.com>, <linux_dti@...oud.com>,
<linux-integrity@...r.kernel.org>, <linux-security-module@...r.kernel.org>,
<akpm@...ux-foundation.org>, <kernel-hardening@...ts.openwall.com>,
<linux-mm@...ck.org>, <will.deacon@....com>, <ard.biesheuvel@...aro.org>,
<kristen@...ux.intel.com>, <deneen.t.dock@...el.com>, Rick Edgecombe
<rick.p.edgecombe@...el.com>, Nadav Amit <namit@...are.com>, Kees Cook
<keescook@...omium.org>, Dave Hansen <dave.hansen@...el.com>, Masami
Hiramatsu <mhiramat@...nel.org>
Subject: [PATCH v5 02/23] 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.
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Kees Cook <keescook@...omium.org>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Nadav Amit <namit@...are.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
---
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) {
--
2.17.1
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