[PATCH v6 6/6] iommu/tegra-smmu: Add pagetable mappings to debugfs

Nicolin Chen
2021-09-14T01:47:43Z

This patch dumps all active mapping entries from pagetable
to a debugfs directory named "mappings".

Attaching an example:

SWGROUP: hc
as->id: 0
as->attr: R|W|N
as->pd_dma: 0x0000000080c03000
{
[index: 1023] 0xf0080c3e (count: 2)
{
PTE RANGE | ATTR | PHYS | IOVA | SIZE
[#1022, #1023] | 0x5 | 0x000000010bbf1000 | 0x00000000ffffe000 | 0x2000
}
}
Total PDE count: 1
Total PTE count: 2

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
drivers/iommu/tegra-smmu.c | 145 +++++++++++++++++++++++++++++++++++++
1 file changed, 145 insertions(+)

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 68c34a4a0ecc..aac977e181f6 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -46,6 +46,7 @@ struct tegra_smmu {
struct list_head list;

struct dentry *debugfs;
+ struct dentry *debugfs_mappings;

struct iommu_device iommu; /* IOMMU Core code handle */
};
@@ -153,6 +154,9 @@ static inline u32 smmu_readl(struct tegra_smmu *smmu, unsigned long offset)

#define SMMU_PDE_ATTR (SMMU_PDE_READABLE | SMMU_PDE_WRITABLE | \
SMMU_PDE_NONSECURE)
+#define SMMU_PTE_ATTR (SMMU_PTE_READABLE | SMMU_PTE_WRITABLE | \
+ SMMU_PTE_NONSECURE)
+#define SMMU_PTE_ATTR_SHIFT 29

static unsigned int iova_pd_index(unsigned long iova)
{
@@ -164,6 +168,12 @@ static unsigned int iova_pt_index(unsigned long iova)
return (iova >> SMMU_PTE_SHIFT) & (SMMU_NUM_PTE - 1);
}

+static unsigned long pd_pt_index_iova(unsigned int pd_index, unsigned int pt_index)
+{
+ return ((dma_addr_t)pd_index & (SMMU_NUM_PDE - 1)) << SMMU_PDE_SHIFT |
+ ((dma_addr_t)pt_index & (SMMU_NUM_PTE - 1)) << SMMU_PTE_SHIFT;
+}
+
static bool smmu_dma_addr_valid(struct tegra_smmu *smmu, dma_addr_t addr)
{
addr >>= 12;
@@ -496,6 +506,8 @@ static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu,
mutex_unlock(&smmu->lock);
}

+static const struct file_operations tegra_smmu_debugfs_mappings_fops;
+
static void tegra_smmu_attach_as(struct tegra_smmu *smmu,
struct tegra_smmu_as *as,
unsigned int swgroup)
@@ -517,6 +529,12 @@ static void tegra_smmu_attach_as(struct tegra_smmu *smmu,
dev_warn(smmu->dev,
"overwriting group->as for swgroup: %s\n", swgrp->name);
group->as = as;
+
+ if (smmu->debugfs_mappings)
+ debugfs_create_file(group->swgrp->name, 0444,
+ smmu->debugfs_mappings, group,
+ &tegra_smmu_debugfs_mappings_fops);
+
break;
}

@@ -541,6 +559,12 @@ static void tegra_smmu_detach_as(struct tegra_smmu *smmu,
if (group->swgrp != swgrp)
continue;
group->as = NULL;
+
+ if (smmu->debugfs_mappings) {
+ d = debugfs_lookup(group->swgrp->name, smmu->debugfs_mappings);
+ debugfs_remove(d);
+ }
+
break;
}

@@ -1124,6 +1148,125 @@ static int tegra_smmu_clients_show(struct seq_file *s, void *data)

DEFINE_SHOW_ATTRIBUTE(tegra_smmu_clients);

+static int tegra_smmu_debugfs_mappings_show(struct seq_file *s, void *data)
+{
+ struct tegra_smmu_group *group = s->private;
+ const struct tegra_smmu_swgroup *swgrp;
+ struct tegra_smmu_as *as;
+ struct tegra_smmu *smmu;
+ unsigned int pd_index;
+ unsigned int pt_index;
+ unsigned long flags;
+ u64 pte_count = 0;
+ u32 pde_count = 0;
+ u32 *pd, val;
+
+ if (!group || !group->as || !group->swgrp)
+ return 0;
+
+ swgrp = group->swgrp;
+ smmu = group->smmu;
+ as = group->as;
+
+ mutex_lock(&smmu->lock);
+
+ val = smmu_readl(smmu, swgrp->reg) & SMMU_ASID_ENABLE;
+ if (!val)
+ goto unlock;
+
+ pd = page_address(as->pd);
+ if (!pd)
+ goto unlock;
+
+ seq_printf(s, "\nSWGROUP: %s\n", swgrp->name);
+ seq_printf(s, "as->id: %d\nas->attr: %c|%c|%s\nas->pd_dma: %pad\n", as->id,
+ as->attr & SMMU_PD_READABLE ? 'R' : '-',
+ as->attr & SMMU_PD_WRITABLE ? 'W' : '-',
+ as->attr & SMMU_PD_NONSECURE ? "NS" : "S",
+ &as->pd_dma);
+ seq_puts(s, "{\n");
+
+ spin_lock_irqsave(&as->lock, flags);
+
+ for (pd_index = 0; pd_index < SMMU_NUM_PDE; pd_index++) {
+ struct page *pt_page;
+ unsigned int i;
+ u32 *addr;
+
+ /* An empty PDE should not have a pte use count */
+ WARN_ON_ONCE(!pd[pd_index] ^ !as->count[pd_index]);
+
+ /* Skip this empty PDE */
+ if (!pd[pd_index])
+ continue;
+
+ pde_count++;
+ pte_count += as->count[pd_index];
+ seq_printf(s, "\t[index: %u] 0x%x (count: %d)\n",
+ pd_index, pd[pd_index], as->count[pd_index]);
+ pt_page = as->pts[pd_index];
+ addr = page_address(pt_page);
+
+ seq_puts(s, "\t{\n");
+ seq_printf(s, "\t\t%-14s | %-4s | %-10s%s | %-10s%s | %-11s\n",
+ "PTE RANGE", "ATTR",
+ "PHYS", sizeof(phys_addr_t) > 4 ? " " : "",
+ "IOVA", sizeof(dma_addr_t) > 4 ? " " : "",
+ "SIZE");
+ for (pt_index = 0; pt_index < SMMU_NUM_PTE; pt_index += i) {
+ size_t size = SMMU_SIZE_PT;
+ dma_addr_t iova;
+ phys_addr_t pa;
+
+ i = 1;
+
+ if (!addr[pt_index])
+ continue;
+
+ iova = pd_pt_index_iova(pd_index, pt_index);
+ pa = SMMU_PFN_PHYS(addr[pt_index] & ~SMMU_PTE_ATTR);
+
+ /* Check contiguous mappings and increase size */
+ while (pt_index + i < SMMU_NUM_PTE) {
+ dma_addr_t next_iova;
+ phys_addr_t next_pa;
+
+ if (!addr[pt_index + i])
+ break;
+
+ next_iova = pd_pt_index_iova(pd_index, pt_index + i);
+ next_pa = SMMU_PFN_PHYS(addr[pt_index + i] & ~SMMU_PTE_ATTR);
+
+ /* Break at the end of a linear mapping */
+ if ((next_iova - iova != SMMU_SIZE_PT * i) ||
+ (next_pa - pa != SMMU_SIZE_PT * i))
+ break;
+
+ i++;
+ }
+
+ seq_printf(s, "\t\t[#%-4u, #%-4u] | 0x%-2x | %pa | %pad | 0x%-9zx\n",
+ pt_index, pt_index + i - 1,
+ addr[pt_index] >> SMMU_PTE_ATTR_SHIFT,
+ &pa, &iova, size * i);
+ }
+ seq_puts(s, "\t}\n");
+ }
+
+ spin_unlock_irqrestore(&as->lock, flags);
+
+ seq_puts(s, "}\n");
+ seq_printf(s, "Total PDE count: %u\n", pde_count);
+ seq_printf(s, "Total PTE count: %llu\n", pte_count);
+
+unlock:
+ mutex_unlock(&smmu->lock);
+
+ return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(tegra_smmu_debugfs_mappings);
+
static void tegra_smmu_debugfs_init(struct tegra_smmu *smmu)
{
smmu->debugfs = debugfs_create_dir("smmu", NULL);
@@ -1134,6 +1277,8 @@ static void tegra_smmu_debugfs_init(struct tegra_smmu *smmu)
&tegra_smmu_swgroups_fops);
debugfs_create_file("clients", S_IRUGO, smmu->debugfs, smmu,
&tegra_smmu_clients_fops);
+
+ smmu->debugfs_mappings = debugfs_create_dir("mappings", smmu->debugfs);
}

static void tegra_smmu_debugfs_exit(struct tegra_smmu *smmu)
--
2.17.1