[PATCH v1 1/1] perf/x86/amd/power: do not load amd power module in intel platform

[PATCH v1 1/1] perf/x86/amd/power: do not load amd power module in intel platform

[Xiao Liang]

"power" module can be loaded if it is not amd processor.

And user cannot unload it after loaded it. The following call trace generated
when tried to unload it.

 BUG: unable to handle kernel NULL pointer dereference at           (null)
 IP: __list_del_entry_valid+0x29/0x90
 PGD 0 P4D 0
 Oops: 0000 [#1] SMP PTI
 CPU: 1 PID: 26046 Comm: modprobe Not tainted 4.14.13-300.fc27.x86_64 #1
 Hardware name: Xen HVM domU, BIOS 4.9.1 12/12/2017
 task: ffff9a138f8dddc0 task.stack: ffffb0ec41cbc000
 RIP: 0010:__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
 RIP: 0033:0x7fb67d78e5c7

Signed-off-by: Xiao Liang <xiliang@redhat.com>
---
 arch/x86/events/amd/power.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/amd/power.c b/arch/x86/events/amd/power.c
index a6eee5ac4f58..2aefacf5c5b2 100644
--- 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(void)
 	int ret;
 
 	if (!x86_match_cpu(cpu_match))
-		return 0;
+		return -ENODEV;
 
 	if (!boot_cpu_has(X86_FEATURE_ACC_POWER))
 		return -ENODEV;
-- 
2.14.3

[tip:x86/urgent] perf/x86/amd/power: Do not load AMD power module on !AMD platforms

[tip-bot for Xiao Liang]

Commit-ID:  40d4071ce2d20840d224b4a77b5dc6f752c9ab15
Gitweb:     https://git.kernel.org/tip/40d4071ce2d20840d224b4a77b5dc6f752c9ab15
Author:     Xiao Liang <xiliang@redhat.com>
AuthorDate: Mon, 22 Jan 2018 14:12:52 +0800
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 24 Jan 2018 13:00:35 +0100

perf/x86/amd/power: Do not load AMD power module on !AMD platforms

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>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180122061252.6394-1-xiliang@redhat.com

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

diff --git a/arch/x86/events/amd/power.c b/arch/x86/events/amd/power.c
index a6eee5a..2aefacf 100644
--- 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(void)
 	int ret;
 
 	if (!x86_match_cpu(cpu_match))
-		return 0;
+		return -ENODEV;
 
 	if (!boot_cpu_has(X86_FEATURE_ACC_POWER))
 		return -ENODEV;