[PATCH v9 1/2] drm/amdgpu: add debugfs for reset registers list

[Christian König]

Am 21.02.22 um 15:19 schrieb Somalapuram, Amaranath:
> [AMD Official Use Only]
>
>
> On 2/21/2022 7:09 PM, Christian König wrote:
>>
>> Am 21.02.22 um 14:34 schrieb Somalapuram Amaranath:
>>> List of register populated for dump collection during the GPU reset.
>>>
>>> Signed-off-by: Somalapuram Amaranath <Amaranath.Somalapuram at amd.com>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu.h         |  4 +
>>>    drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 96 +++++++++++++++++++++
>>>    2 files changed, 100 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index b85b67a88a3d..6e35f2c4c869 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -1097,6 +1097,10 @@ struct amdgpu_device {
>>>          struct amdgpu_reset_control     *reset_cntl;
>>>        uint32_t ip_versions[HW_ID_MAX][HWIP_MAX_INSTANCE];
>>> +
>>> +    /* reset dump register */
>>> +    uint32_t            *reset_dump_reg_list;
>>> +    int                             num_regs;
>>>    };
>>>      static inline struct amdgpu_device *drm_to_adev(struct drm_device
>>> *ddev)
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> index 164d6a9e9fbb..69c0a28deeac 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
>>> @@ -1609,6 +1609,100 @@ DEFINE_DEBUGFS_ATTRIBUTE(fops_ib_preempt, NULL,
>>>    DEFINE_DEBUGFS_ATTRIBUTE(fops_sclk_set, NULL,
>>>                amdgpu_debugfs_sclk_set, "%llu\n");
>>>    +static ssize_t amdgpu_reset_dump_register_list_read(struct file *f,
>>> +                char __user *buf, size_t size, loff_t *pos)
>>> +{
>>> +    struct amdgpu_device *adev = (struct amdgpu_device
>>> *)file_inode(f)->i_private;
>>> +    char reg_offset[11];
>>> +    int i, ret, len = 0;
>>> +
>>> +    if (*pos)
>>> +        return 0;
>>> +
>>> +    ret = down_read_killable(&adev->reset_sem);
>>> +
>>> +    if (ret)
>>> +        return ret;
>> We usually don't have an empty line between function call and checking
>> the return code.
>>
>>> +
>>> +    for (i = 0; i < adev->num_regs; i++) {
>>> +        down_read(&adev->reset_sem);
>> That here will just crash because we have already locked the semaphore
>> before the loop.
>>
> unfortunately it did not crash. Sorry I misunderstood your earlier comments.
>>> +        sprintf(reg_offset, "0x%x ", adev->reset_dump_reg_list[i]);
>>> +        up_read(&adev->reset_sem);
>>> +        ret = copy_to_user(buf + len, reg_offset, strlen(reg_offset));
>>> +
>>> +        if (ret)
>>> +            goto error;
>>> +
>>> +        len += strlen(reg_offset);
>> And here the down_read_killable() is missing.
>>
>>> +    }
>>> +
>>> +    up_read(&adev->reset_sem);
>>> +    ret = copy_to_user(buf + len, "\n", 1);
>>> +
>>> +    if (ret)
>>> +        return -EFAULT;
>>> +
>>> +    len++;
>>> +    *pos += len;
>>> +
>>> +    return len;
>>> +error:
>>> +    up_read(&adev->reset_sem);
>>> +    return -EFAULT;
>>> +}
>>> +
>>> +static ssize_t amdgpu_reset_dump_register_list_write(struct file *f,
>>> +            const char __user *buf, size_t size, loff_t *pos)
>>> +{
>>> +    struct amdgpu_device *adev = (struct amdgpu_device
>>> *)file_inode(f)->i_private;
>>> +    char *reg_offset, *reg, reg_temp[11];
>>> +    uint32_t *tmp;
>>> +    int ret, i = 0, len = 0;
>>> +
>>> +    do {
>>> +        reg_offset = reg_temp;
>> I think you can just drop the reg_offset variable;
>>
> strsep takes only pointer as input, this is workaround.

Ah, now I see what you are doing here.

Please don't do it like that. Better use memchr() instead.

>>> +        memset(reg_offset, 0, 11);
>>> +        ret = copy_from_user(reg_offset, buf + len, min(11,
>>> ((int)size-len)));
>>> +
>>> +        if (ret)
>>> +            goto error_free;
>>> +
>>> +        reg = strsep(&reg_offset, " ");
>>> +        tmp = krealloc_array(tmp, 1, sizeof(uint32_t), GFP_KERNEL);
>> That must be krealloc_array(tmp, i, ... not krealloc_array(tmp, 1, ... !
> I thought it will append (if not it should have crashed or some kernel dump)

No, krealloc_array works similar to realloc() in userspace.

You need to give it the full size of the necessary space.

Regards,
Christian.

>> Regards,
>> Christian.
>>
>>> +        ret = kstrtouint(reg, 16, &tmp[i]);
>>> +
>>> +        if (ret)
>>> +            goto error_free;
>>> +
>>> +        len += strlen(reg) + 1;
>>> +        i++;
>>> +
>>> +    } while (len < size);
>>> +
>>> +    ret = down_write_killable(&adev->reset_sem);
>>> +
>>> +    if (ret)
>>> +        goto error_free;
>>> +
>>> +    swap(adev->reset_dump_reg_list, tmp);
>>> +    adev->num_regs = i;
>>> +    up_write(&adev->reset_sem);
>>> +    ret = size;
>>> +
>>> +error_free:
>>> +    kfree(tmp);
>>> +    return ret;
>>> +}
>>> +
>>> +
>>> +
>>> +static const struct file_operations amdgpu_reset_dump_register_list = {
>>> +    .owner = THIS_MODULE,
>>> +    .read = amdgpu_reset_dump_register_list_read,
>>> +    .write = amdgpu_reset_dump_register_list_write,
>>> +    .llseek = default_llseek
>>> +};
>>> +
>>>    int amdgpu_debugfs_init(struct amdgpu_device *adev)
>>>    {
>>>        struct dentry *root = adev_to_drm(adev)->primary->debugfs_root;
>>> @@ -1672,6 +1766,8 @@ int amdgpu_debugfs_init(struct amdgpu_device
>>> *adev)
>>>                    &amdgpu_debugfs_test_ib_fops);
>>>        debugfs_create_file("amdgpu_vm_info", 0444, root, adev,
>>>                    &amdgpu_debugfs_vm_info_fops);
>>> +    debugfs_create_file("amdgpu_reset_dump_register_list", 0644,
>>> root, adev,
>>> +                &amdgpu_reset_dump_register_list);
>>>          adev->debugfs_vbios_blob.data = adev->bios;
>>>        adev->debugfs_vbios_blob.size = adev->bios_size;
> >