Fix build warnings and errors on Linux 6.14ecrts25-ae

- Remove repetitive declarations of two `bus_type` structs.
- Fix mmu.c to use an always-64-bit member for `parent_addr`.
- Remove call to `page_mapcount_reset()` that isn't needed.
- Correct `nvdebug_pd_page` documentation.
- Disable missing prototype and missing declaration warnings.
- Fix an improper type, and a missing type conversion.

Tested build on Linux 6.14.0 (x86_64), 5.4.0 (x86_64), and
4.9.337 (aarch64).

5 files changed, 16 insertions, 19 deletions

diff --git a/Makefile b/Makefile
index 9d6d374..e7b160c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,8 @@
 obj-m += nvdebug.o
 nvdebug-objs = runlist_procfs.o device_info_procfs.o runlist.o mmu.o \
                nvdebug_entry.o bus.o nvdebug_linux.o copy_topology_procfs.o
-KBUILD_CFLAGS += -DGIT_HASH=\"$(shell git --git-dir=$(PWD)/.git rev-parse --short HEAD)\"
+KBUILD_CFLAGS += -DGIT_HASH=\"$(shell git --git-dir=$(PWD)/.git rev-parse --short HEAD)\" \
+                 -Wno-missing-prototypes -Wno-missing-declarations
 # -mfentry above if not building due to mcount missing
 
 all:
diff --git a/mmu.c b/mmu.c
index e2b9a91..bab2ea0 100644
--- a/mmu.c
+++ b/mmu.c
@@ -229,19 +229,20 @@ int translate_page_directory(struct nvdebug_state *g,
 // explictly permitted (see linux/mm_types.h). This struct is thus used by
 // casting a pointer of struct page to a pointer of struct nvdebug_pd_page,
 // then accessing the associated fields. This pointer may also be freely cast
-// back to a sturct page pointer.
-// We have 24 (32-bit) or 44 (64-bit) bytes available in the page struct
-// (according to the documentation on struct page). Our comments indicate what
-// available parts of struct page we repurpose for our own needs.
+// back to a struct page pointer.
+// We have 20 (32-bit) or 40 (64-bit) bytes available in the page struct
+// (according to the documentation on struct page). We use 20 (32-bit) or 28
+// (64-bit) bytes. Our comments indicate what available parts of struct page we
+// repurpose for our own needs.
 struct nvdebug_pd_page {
         unsigned long __flags; // From struct page; do not touch!
         // Overlaps struct page.lru
         struct list_head list; // 4/8 bytes
-        // Overlaps struct page.mapping (and page.share on 32-bit)
-        uintptr_t parent_addr; // 8 bytes
-        // Overlaps struct page.share (page.private on 32-bit)
+        // Overlaps struct page.lru (and page.mapping on 32-bit)
+        uint64_t parent_addr; // 8 bytes
+        // Overlaps struct page.mapping (page.share on 32-bit)
         enum PD_TARGET parent_aperture; // 4 bytes
-        // Overlaps page.private (page.page_type on 32-bit)
+        // Overlaps page.mapping and page.share (page.private on 32-bit)
         dma_addr_t dma_addr; // 4/8 bytes
 };
 
@@ -262,12 +263,12 @@ int gc_page_directory(struct nvdebug_state *g, bool force) {
         // (This is depth-first because map_page_directory() always allocates and
         // pushes page directory allocations before page table allocations.)
         list_for_each_entry_safe_reverse(page, _page, &g->pd_allocs, list) {
-                printk_debug(KERN_DEBUG "[nvdebug] %s: Checking if page directory/table at %llx (SYS_MEM_?) with parent at %lx (%s) is unused...\n", __func__, page->dma_addr, page->parent_addr, pd_target_to_text(page->parent_aperture));
+                printk_debug(KERN_DEBUG "[nvdebug] %s: Checking if page directory/table at %llx (SYS_MEM_?) with parent at %llx (%s) is unused...\n", __func__, page->dma_addr, page->parent_addr, pd_target_to_text(page->parent_aperture));
                 // Try to determine if we're still in-use. We consider ourselves
                 // potentially in-use if our parent still points to us.
                 parent_kva = pd_deref(g, page->parent_addr, page->parent_aperture);
                 if (IS_ERR(parent_kva)) {
-                        printk(KERN_ERR "[nvdebug] %s: Error resolving %#lx in GPU %s to a kernel-accessible address. Error %ld.\n", __func__, page->parent_addr, pd_target_to_text(page->parent_aperture), PTR_ERR(parent_kva));
+                        printk(KERN_ERR "[nvdebug] %s: Error resolving %#llx in GPU %s to a kernel-accessible address. Error %ld.\n", __func__, page->parent_addr, pd_target_to_text(page->parent_aperture), PTR_ERR(parent_kva));
                         return -ENOTRECOVERABLE;
                 }
                 // A NULL kva indicates parent no longer exists
@@ -277,14 +278,12 @@ int gc_page_directory(struct nvdebug_state *g, bool force) {
                         continue;
                 // Free this page table/directory and delete our parent's pointer to us
                 if (parent_entry.addr_w == (page->dma_addr >> 12)) {
-                        printk(KERN_WARNING "[nvdebug] %s: Deleting page table/directory at %llx (SYS_MEM_?) with parent at %lx (%s) that may still be in-use!\n", __func__, page->dma_addr, page->parent_addr, pd_target_to_text(page->parent_aperture));
+                        printk(KERN_WARNING "[nvdebug] %s: Deleting page table/directory at %llx (SYS_MEM_?) with parent at %llx (%s) that may still be in-use!\n", __func__, page->dma_addr, page->parent_addr, pd_target_to_text(page->parent_aperture));
                         writeq(0, parent_kva);
                 }
                 // Unmap, zero, free, and remove from tracking (these all return void)
                 dma_unmap_page(g->dev, page->dma_addr, PAGE_SIZE, DMA_TO_DEVICE);
                 memset(page_to_virt((struct page*)page), 0, PAGE_SIZE);
-                // Necessary to reset mapcount as we (ab)use its state for other things
-                page_mapcount_reset((struct page*)page);
                 // Same reset needed for mapping
                 ((struct page*)page)->mapping = NULL;
                 // Remove this page from our list of allocated pages
@@ -607,7 +606,7 @@ int translate_v1_page_directory(struct nvdebug_state *g,
         // Convert VID_MEM/SYS_MEM address to Kernel-accessible Virtual Address (KVA)
         pte_kva = pd_deref(g, pte_phys, V12PD_TARGET(pde.alt_target));
         if (IS_ERR_OR_NULL(pde_kva)) {
-                printk(KERN_ERR "[nvdebug] %s: Unable to resolve %#lx in GPU %s to a kernel-accessible address. Error %ld.\n", __func__, pte_phys, pd_target_to_text(pde.alt_target), PTR_ERR(pte_kva));
+                printk(KERN_ERR "[nvdebug] %s: Unable to resolve %#lx in GPU %s to a kernel-accessible address. Error %ld.\n", __func__, pte_phys, pd_target_to_text(V12PD_TARGET(pde.alt_target)), PTR_ERR(pte_kva));
                 return PTR_ERR(pte_kva);
         }
         // Read page table entry
diff --git a/nvdebug.h b/nvdebug.h
index 3ac8db4..ecfb051 100644
--- a/nvdebug.h
+++ b/nvdebug.h
@@ -1620,7 +1620,7 @@ static inline const char *compute_preempt_type_to_text(enum COMPUTE_PREEMPT_TYPE
                         return "INVALID";
         }
 }
-static inline const char *graphics_preempt_type_to_text(enum COMPUTE_PREEMPT_TYPE t) {
+static inline const char *graphics_preempt_type_to_text(enum GRAPHICS_PREEMPT_TYPE t) {
         switch (t) {
                 case PREEMPT_WFI:
                         return "WFI";
diff --git a/nvdebug_entry.c b/nvdebug_entry.c
index c0cfa63..8293fdc 100644
--- a/nvdebug_entry.c
+++ b/nvdebug_entry.c
@@ -48,8 +48,6 @@ extern struct file_operations copy_topology_file_ops;
 
 struct nvdebug_state g_nvdebug_state[NVDEBUG_MAX_DEVICES];
 unsigned int g_nvdebug_devices = 0;
-// Bus types are global symbols in the kernel
-extern struct bus_type platform_bus_type;
 
 // Starting in Kernel 5.6, proc_ops is required instead of file_operations.
 // As file_operations is larger than proc_ops, we can overwrite the memory
diff --git a/stubs.h b/stubs.h
index b909587..da14bed 100644
--- a/stubs.h
+++ b/stubs.h
@@ -29,7 +29,6 @@ pci_match_one_device(const struct pci_device_id *id, const struct pci_dev *dev)
 // Functions from drivers/pci/search.h
 #include <linux/device.h>
 #include <linux/pci.h>
-extern struct bus_type pci_bus_type;
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(5,3,0)
 static int match_pci_dev_by_id(struct device *dev, void *data)