drm/amdgpu: Fix cat debugfs amdgpu_regs_didt causes kernel null pointer

For 'AMDGPU_FAMILY_SI' family cards, in 'si_common_early_init' func, init
'didt_rreg' and 'didt_wreg' to 'NULL'. But in func
'amdgpu_debugfs_regs_didt_read/write', using 'RREG32_DIDT' 'WREG32_DIDT'
lacks of relevant judgment. And other 'amdgpu_ip_block_version' that use
these two definitions won't be added for 'AMDGPU_FAMILY_SI'.

So, add null pointer judgment before calling.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Lu Yao <yaolu@kylinos.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index a53f436fa9f1ae7c0129f8e58dd212ad70dfd0aa..0e61ebdb3f3e5999dc34f8f2f478e0a8ba41ae45 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -638,6 +638,9 @@ static ssize_t amdgpu_debugfs_regs_didt_read(struct file *f, char __user *buf,
        if (size & 0x3 || *pos & 0x3)
                return -EINVAL;
 
+       if (!adev->didt_rreg)
+               return -EOPNOTSUPP;
+
        r = pm_runtime_get_sync(adev_to_drm(adev)->dev);
        if (r < 0) {
                pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);
@@ -694,6 +697,9 @@ static ssize_t amdgpu_debugfs_regs_didt_write(struct file *f, const char __user
        if (size & 0x3 || *pos & 0x3)
                return -EINVAL;
 
+       if (!adev->didt_wreg)
+               return -EOPNOTSUPP;
+
        r = pm_runtime_get_sync(adev_to_drm(adev)->dev);
        if (r < 0) {
                pm_runtime_put_autosuspend(adev_to_drm(adev)->dev);