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

Somalapuram, Amaranath Amaranath.Somalapuram at amd.com
Mon Feb 21 17:15:18 UTC 2022


[AMD Official Use Only]



On 2/21/2022 7:58 PM, Christian König wrote:
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><mailto: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.

memchr will not work. I couldn't find any other string API I can use.

other references similar to code:
static void amdgpu_device_enable_virtual_display(struct amdgpu_device *adev)
{
    adev->enable_virtual_display = false;

    if (amdgpu_virtual_display) {
        const char *pci_address_name = pci_name(adev->pdev);
        char *pciaddstr, *pciaddstr_tmp, *pciaddname_tmp, *pciaddname;

        pciaddstr = kstrdup(amdgpu_virtual_display, GFP_KERNEL);
        pciaddstr_tmp = pciaddstr;
        while ((pciaddname_tmp = strsep(&pciaddstr_tmp, ";"))) {
            pciaddname = strsep(&pciaddname_tmp, ",");


+        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;
>

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