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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, Xiao Liang <xiliang@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 4.9 56/66] perf/x86/amd/power: Do not load AMD power module on !AMD platforms
Date:   Mon, 29 Jan 2018 13:57:20 +0100
Message-Id: <20180129123842.849951138@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Xiao Liang <xiliang@redhat.com>

commit 40d4071ce2d20840d224b4a77b5dc6f752c9ab15 upstream.

The AMD power module can be loaded on non AMD platforms, but unload fails
with the following Oops:

 BUG: unable to handle kernel NULL pointer dereference at           (null)
 IP: __list_del_entry_valid+0x29/0x90
 Call Trace:
  perf_pmu_unregister+0x25/0xf0
  amd_power_pmu_exit+0x1c/0xd23 [power]
  SyS_delete_module+0x1a8/0x2b0
  ? exit_to_usermode_loop+0x8f/0xb0
  entry_SYSCALL_64_fastpath+0x20/0x83

Return -ENODEV instead of 0 from the module init function if the CPU does
not match.

Fixes: c7ab62bfbe0e ("perf/x86/amd/power: Add AMD accumulated power reporting mechanism")
Signed-off-by: Xiao Liang <xiliang@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20180122061252.6394-1-xiliang@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/events/amd/power.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/events/amd/power.c
+++ b/arch/x86/events/amd/power.c
@@ -277,7 +277,7 @@ static int __init amd_power_pmu_init(voi
 	int ret;
 
 	if (!x86_match_cpu(cpu_match))
-		return 0;
+		return -ENODEV;
 
 	if (!boot_cpu_has(X86_FEATURE_ACC_POWER))
 		return -ENODEV;