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

[Nicolin Chen]

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@xxxxxxxxx>
---
 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