drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling

When users try to remove PMU modules during perf sampling, kernel panic
will happen because the pmu->read() is a NULL pointer here.

INFO on HiSilicon hip08 platform as follow:
pc : hisi_uncore_pmu_event_update+0x30/0xa4 [hisi_uncore_pmu]
lr : hisi_uncore_pmu_read+0x20/0x2c [hisi_uncore_pmu]
sp : ffff800010103e90
x29: ffff800010103e90 x28: ffff0027db0c0e40
x27: ffffa29a76f129d8 x26: ffffa29a77ceb000
x25: ffffa29a773a5000 x24: ffffa29a77392000
x23: ffffddffe5943f08 x22: ffff002784285960
x21: ffff002784285800 x20: ffff0027d2e76c80
x19: ffff0027842859e0 x18: ffff80003498bcc8
x17: ffffa29a76afe910 x16: ffffa29a7583f530
x15: 16151a1512061a1e x14: 0000000000000000
x13: ffffa29a76f1e238 x12: 0000000000000001
x11: 0000000000000400 x10: 00000000000009f0
x9 : ffff8000107b3e70 x8 : ffff0027db0c1890
x7 : ffffa29a773a7000 x6 : 00000007f5131013
x5 : 00000007f5131013 x4 : 09f257d417c00000
x3 : 00000002187bd7ce x2 : ffffa29a38f0f0d8
x1 : ffffa29a38eae268 x0 : ffff0027d2e76c80
Call trace:
hisi_uncore_pmu_event_update+0x30/0xa4 [hisi_uncore_pmu]
hisi_uncore_pmu_read+0x20/0x2c [hisi_uncore_pmu]
__perf_event_read+0x1a0/0x1f8
flush_smp_call_function_queue+0xa0/0x160
generic_smp_call_function_single_interrupt+0x18/0x20
handle_IPI+0x31c/0x4dc
gic_handle_irq+0x2c8/0x310
el1_irq+0xcc/0x180
arch_cpu_idle+0x4c/0x20c
default_idle_call+0x20/0x30
do_idle+0x1b4/0x270
cpu_startup_entry+0x28/0x30
secondary_start_kernel+0x1a4/0x1fc

To solve the above issue, current module should be registered to kernel,
so that try_module_get() can be invoked when perf sampling starts. This
adds the reference counting of module and could prevent users from removing
modules during sampling.
Reported-by: Haifeng Wang <wang.wanghaifeng@huawei.com>
Signed-off-by: Qi Liu <liuqi115@huawei.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Link: https://lore.kernel.org/r/1594891165-8228-1-git-send-email-liuqi115@huawei.comSigned-off-by: Will Deacon <will@kernel.org>

drivers/perf/arm_smmuv3_pmu.c

@@ -742,6 +742,7 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, smmu_pmu);
 
 	smmu_pmu->pmu = (struct pmu) {
+		.module		= THIS_MODULE,
 		.task_ctx_nr    = perf_invalid_context,
 		.pmu_enable	= smmu_pmu_enable,
 		.pmu_disable	= smmu_pmu_disable,

drivers/perf/fsl_imx8_ddr_perf.c

@@ -512,6 +512,7 @@ static int ddr_perf_init(struct ddr_pmu *pmu, void __iomem *base,
 {
 	*pmu = (struct ddr_pmu) {
 		.pmu = (struct pmu) {
+			.module	      = THIS_MODULE,
 			.capabilities = PERF_PMU_CAP_NO_EXCLUDE,
 			.task_ctx_nr = perf_invalid_context,
 			.attr_groups = attr_groups,

drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c

@@ -378,6 +378,7 @@ static int hisi_ddrc_pmu_probe(struct platform_device *pdev)
 			      ddrc_pmu->sccl_id, ddrc_pmu->index_id);
 	ddrc_pmu->pmu = (struct pmu) {
 		.name		= name,
+		.module		= THIS_MODULE,
 		.task_ctx_nr	= perf_invalid_context,
 		.event_init	= hisi_uncore_pmu_event_init,
 		.pmu_enable	= hisi_uncore_pmu_enable,

drivers/perf/hisilicon/hisi_uncore_hha_pmu.c

@@ -390,6 +390,7 @@ static int hisi_hha_pmu_probe(struct platform_device *pdev)
 			      hha_pmu->sccl_id, hha_pmu->index_id);
 	hha_pmu->pmu = (struct pmu) {
 		.name		= name,
+		.module		= THIS_MODULE,
 		.task_ctx_nr	= perf_invalid_context,
 		.event_init	= hisi_uncore_pmu_event_init,
 		.pmu_enable	= hisi_uncore_pmu_enable,

drivers/perf/hisilicon/hisi_uncore_l3c_pmu.c

@@ -380,6 +380,7 @@ static int hisi_l3c_pmu_probe(struct platform_device *pdev)
 			      l3c_pmu->sccl_id, l3c_pmu->index_id);
 	l3c_pmu->pmu = (struct pmu) {
 		.name		= name,
+		.module		= THIS_MODULE,
 		.task_ctx_nr	= perf_invalid_context,
 		.event_init	= hisi_uncore_pmu_event_init,
 		.pmu_enable	= hisi_uncore_pmu_enable,