[PATCH 4.19 102/115] coresight: tmc-etf: Do not call smp_processor_id from preemptible

Greg Kroah-Hartman
2020-01-07T21:07:56Z

From: Suzuki K Poulose <suzuki.poulose@arm.com>

[ Upstream commit 024c1fd9dbcc1d8a847f1311f999d35783921b7f ]

During a perf session we try to allocate buffers on the "node" associated
with the CPU the event is bound to. If it is not bound to a CPU, we
use the current CPU node, using smp_processor_id(). However this is unsafe
in a pre-emptible context and could generate the splats as below :

BUG: using smp_processor_id() in preemptible [00000000] code: perf/2544
caller is tmc_alloc_etf_buffer+0x5c/0x60
CPU: 2 PID: 2544 Comm: perf Not tainted 5.1.0-rc6-147786-g116841e #344
Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb 1 2019
Call trace:
dump_backtrace+0x0/0x150
show_stack+0x14/0x20
dump_stack+0x9c/0xc4
debug_smp_processor_id+0x10c/0x110
tmc_alloc_etf_buffer+0x5c/0x60
etm_setup_aux+0x1c4/0x230
rb_alloc_aux+0x1b8/0x2b8
perf_mmap+0x35c/0x478
mmap_region+0x34c/0x4f0
do_mmap+0x2d8/0x418
vm_mmap_pgoff+0xd0/0xf8
ksys_mmap_pgoff+0x88/0xf8
__arm64_sys_mmap+0x28/0x38
el0_svc_handler+0xd8/0x138
el0_svc+0x8/0xc

Use NUMA_NO_NODE hint instead of using the current node for events
not bound to CPUs.

Fixes: 2e499bbc1a929ac ("coresight: tmc: implementing TMC-ETF AUX space API")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: stable <stable@vger.kernel.org> # 4.7+
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20190620221237.3536-4-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwtracing/coresight/coresight-tmc-etf.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index e31061308e19..4644ac5582cf 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -304,9 +304,7 @@ static void *tmc_alloc_etf_buffer(struct coresight_device *csdev, int cpu,
int node;
struct cs_buffers *buf;

- if (cpu == -1)
- cpu = smp_processor_id();
- node = cpu_to_node(cpu);
+ node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);

/* Allocate memory structure for interaction with Perf */
buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
--
2.20.1