[PATCH 2/2] adreno: Detect shutdown during get_param()

["Joel Fernandes (Google)" <joel@joelfernandes.org>]

Even though the GPU is shut down, during kexec reboot we can have userspace
still running. This is especially true if KEXEC_JUMP is not enabled, because we
do not freeze userspace in this case.

To prevent crashes, track that the GPU is shutdown and prevent get_param() from
accessing GPU resources if we find it shutdown.

This fixes the following crash during kexec reboot on an ARM64 device with adreno GPU:

[  292.534314] Kernel panic - not syncing: Asynchronous SError Interrupt
[  292.534323] Hardware name: Google Lazor (rev3 - 8) with LTE (DT)
[  292.534326] Call trace:
[  292.534328]  dump_backtrace+0x0/0x1d4
[  292.534337]  show_stack+0x20/0x2c
[  292.534342]  dump_stack_lvl+0x60/0x78
[  292.534347]  dump_stack+0x18/0x38
[  292.534352]  panic+0x148/0x3b0
[  292.534357]  nmi_panic+0x80/0x94
[  292.534364]  arm64_serror_panic+0x70/0x7c
[  292.534369]  do_serror+0x0/0x7c
[  292.534372]  do_serror+0x54/0x7c
[  292.534377]  el1h_64_error_handler+0x34/0x4c
[  292.534381]  el1h_64_error+0x7c/0x80
[  292.534386]  el1_interrupt+0x20/0x58
[  292.534389]  el1h_64_irq_handler+0x18/0x24
[  292.534395]  el1h_64_irq+0x7c/0x80
[  292.534399]  local_daif_inherit+0x10/0x18
[  292.534405]  el1h_64_sync_handler+0x48/0xb4
[  292.534410]  el1h_64_sync+0x7c/0x80
[  292.534414]  a6xx_gmu_set_oob+0xbc/0x1fc
[  292.534422]  a6xx_get_timestamp+0x40/0xb4
[  292.534426]  adreno_get_param+0x12c/0x1e0
[  292.534433]  msm_ioctl_get_param+0x64/0x70
[  292.534440]  drm_ioctl_kernel+0xe8/0x158
[  292.534448]  drm_ioctl+0x208/0x320
[  292.534453]  __arm64_sys_ioctl+0x98/0xd0
[  292.534461]  invoke_syscall+0x4c/0x118
[  292.534467]  el0_svc_common+0x98/0x104
[  292.534473]  do_el0_svc+0x30/0x80
[  292.534478]  el0_svc+0x20/0x50
[  292.534481]  el0t_64_sync_handler+0x78/0x108
[  292.534485]  el0t_64_sync+0x1a4/0x1a8
[  292.534632] Kernel Offset: 0x1a5f800000 from 0xffffffc008000000
[  292.534635] PHYS_OFFSET: 0x80000000
[  292.534638] CPU features: 0x40018541,a3300e42
[  292.534644] Memory Limit: none

Cc: Rob Clark <robdclark@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ricardo Ribalda <ribalda@chromium.org>
Cc: Ross Zwisler <zwisler@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 drivers/gpu/drm/msm/adreno/adreno_device.c | 1 +
 drivers/gpu/drm/msm/adreno/adreno_gpu.c    | 2 +-
 drivers/gpu/drm/msm/msm_gpu.h              | 3 +++
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
index f0cff62812c3..03d912dc0130 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_device.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
@@ -612,6 +612,7 @@ static void adreno_shutdown(struct platform_device *pdev)
 {
 	struct msm_gpu *gpu = dev_to_gpu(&pdev->dev);
 
+	gpu->is_shutdown = true;
 	WARN_ON_ONCE(adreno_system_suspend(&pdev->dev));
 }
 
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index 382fb7f9e497..6903c6892469 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -251,7 +251,7 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_file_private *ctx,
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 
 	/* No pointer params yet */
-	if (*len != 0)
+	if (*len != 0 || gpu->is_shutdown)
 		return -EINVAL;
 
 	switch (param) {
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index ff911e7305ce..f18b0a91442b 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -214,6 +214,9 @@ struct msm_gpu {
 	/* does gpu need hw_init? */
 	bool needs_hw_init;
 
+	/* is the GPU shutdown? */
+	bool is_shutdown;
+
 	/**
 	 * global_faults: number of GPU hangs not attributed to a particular
 	 * address space
-- 
2.38.1.493.g58b659f92b-goog