From f09444639099584bc4784dfcd85ada67c6f33e0f Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Mon, 23 Jan 2017 10:41:22 -0700 Subject: [PATCH] coresight: fix kernel panic caused by invalid CPU Commit d52c9750f150 ("coresight: reset "enable_sink" flag when need be") caused a kernel panic because of the using of an invalid value: after 'for_each_cpu(cpu, mask)', value of local variable 'cpu' become invalid, causes following 'cpu_to_node' access invalid memory area. This patch brings the deleted 'cpu = cpumask_first(mask)' back. Panic log: $ perf record -e cs_etm// ls Unable to handle kernel paging request at virtual address fffe801804af4f10 pgd = ffff8017ce031600 [fffe801804af4f10] *pgd=0000000000000000, *pud=0000000000000000 Internal error: Oops: 96000004 [#1] SMP Modules linked in: CPU: 33 PID: 1619 Comm: perf Not tainted 4.7.1+ #16 Hardware name: Huawei Taishan 2280 /CH05TEVBA, BIOS 1.10 11/24/2016 task: ffff8017cb0c8400 ti: ffff8017cb154000 task.ti: ffff8017cb154000 PC is at tmc_alloc_etf_buffer+0x60/0xd4 LR is at tmc_alloc_etf_buffer+0x44/0xd4 pc : [] lr : [] pstate: 60000145 sp : ffff8017cb157b40 x29: ffff8017cb157b40 x28: 0000000000000000 ...skip... 7a60: ffff000008c64dc8 0000000000000006 0000000000000253 ffffffffffffffff 7a80: 0000000000000000 0000000000000000 ffff0000080872cc 0000000000000001 [] tmc_alloc_etf_buffer+0x60/0xd4 [] etm_setup_aux+0x1dc/0x1e8 [] rb_alloc_aux+0x2b0/0x338 [] perf_mmap+0x414/0x568 [] mmap_region+0x324/0x544 [] do_mmap+0x334/0x3e0 [] vm_mmap_pgoff+0xa4/0xc8 [] SyS_mmap_pgoff+0xb0/0x22c [] sys_mmap+0x18/0x28 [] el0_svc_naked+0x24/0x28 Code: 912040a5 d0001c00 f873d821 911c6000 (b8656822) ---[ end trace 98933da8f92b0c9a ]--- Signed-off-by: Wang Nan Cc: Xia Kaixu Cc: Li Zefan Cc: Mathieu Poirier Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Fixes: d52c9750f150 ("coresight: reset "enable_sink" flag when need be") Signed-off-by: Mathieu Poirier Cc: stable # 4.10 Signed-off-by: Greg Kroah-Hartman --- drivers/hwtracing/coresight/coresight-etm-perf.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c index 1774196..26cfac3 100644 --- a/drivers/hwtracing/coresight/coresight-etm-perf.c +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c @@ -242,6 +242,7 @@ static void *etm_setup_aux(int event_cpu, void **pages, if (!sink_ops(sink)->alloc_buffer) goto err; + cpu = cpumask_first(mask); /* Get the AUX specific data from the sink buffer */ event_data->snk_config = sink_ops(sink)->alloc_buffer(sink, cpu, pages, -- 2.7.4