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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Borislav Petkov <bp@suse.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0640/1039] x86/mce: Allow instrumentation during task work queueing
Date:   Mon, 24 Jan 2022 19:40:29 +0100
Message-Id: <20220124184146.865221335@linuxfoundation.org>
In-Reply-To: <20220124184125.121143506@linuxfoundation.org>
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From: Borislav Petkov <bp@suse.de>

[ Upstream commit 4fbce464db81a42f9a57ee242d6150ec7f996415 ]

Fixes

  vmlinux.o: warning: objtool: do_machine_check()+0xdb1: call to queue_task_work() leaves .noinstr.text section

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211208111343.8130-6-bp@alien8.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kernel/cpu/mce/core.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 6ed365337a3b1..70ec5685906b2 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1454,6 +1454,14 @@ noinstr void do_machine_check(struct pt_regs *regs)
 	if (worst != MCE_AR_SEVERITY && !kill_current_task)
 		goto out;
 
+	/*
+	 * Enable instrumentation around the external facilities like
+	 * task_work_add() (via queue_task_work()), fixup_exception() etc.
+	 * For now, that is. Fixing this properly would need a lot more involved
+	 * reorganization.
+	 */
+	instrumentation_begin();
+
 	/* Fault was in user mode and we need to take some action */
 	if ((m.cs & 3) == 3) {
 		/* If this triggers there is no way to recover. Die hard. */
@@ -1482,6 +1490,9 @@ noinstr void do_machine_check(struct pt_regs *regs)
 		if (m.kflags & MCE_IN_KERNEL_COPYIN)
 			queue_task_work(&m, msg, kill_me_never);
 	}
+
+	instrumentation_end();
+
 out:
 	mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
 }
-- 
2.34.1