Add some dumb test code

sw/test/Makefile

@@ -0,0 +1,18 @@
+
+BIN=pcie_dma_test
+
+SRCS=$(wildcard *.c)
+OBJS=$(SRCS:.c=.o)
+
+all: $(BIN)
+
+$(BIN): $(OBJS)
+	gcc -o $@ $(CFLAGS) $(LDFLAGS) $^
+
+%.o: %.c
+	gcc -c -o $@ $(CFLAGS) $<
+
+.PHONY: clean
+clean:
+	rm -rf $(OBJS)
+	rm -rf $(BIN)

sw/test/enable_bus_mastering.sh

@@ -0,0 +1,2 @@
+# Enable bus mastering
+sudo setpci -d 10EE:9038 COMMAND=7

sw/test/pcie_dma_test.c

@@ -0,0 +1,102 @@
+#define _XOPEN_SOURCE 700
+#include <fcntl.h> /* open */
+#include <stdint.h> /* uint64_t  */
+#include <stdio.h> /* printf */
+#include <stdlib.h> /* size_t */
+#include <unistd.h> /* pread, sysconf */
+#include <sys/mman.h>
+
+typedef struct {
+    uint64_t pfn : 55;
+    unsigned int soft_dirty : 1;
+    unsigned int file_page : 1;
+    unsigned int swapped : 1;
+    unsigned int present : 1;
+} PagemapEntry;
+
+/* Parse the pagemap entry for the given virtual address.
+ *
+ * @param[out] entry      the parsed entry
+ * @param[in]  pagemap_fd file descriptor to an open /proc/pid/pagemap file
+ * @param[in]  vaddr      virtual address to get entry for
+ * @return 0 for success, 1 for failure
+ */
+int pagemap_get_entry(PagemapEntry *entry, int pagemap_fd, uintptr_t vaddr)
+{
+    size_t nread;
+    ssize_t ret;
+    uint64_t data;
+    uintptr_t vpn;
+
+    vpn = vaddr / sysconf(_SC_PAGE_SIZE);
+    nread = 0;
+    while (nread < sizeof(data)) {
+        ret = pread(pagemap_fd, ((uint8_t*)&data) + nread, sizeof(data) - nread,
+                vpn * sizeof(data) + nread);
+        nread += ret;
+        if (ret <= 0) {
+            return 1;
+        }
+    }
+    entry->pfn = data & (((uint64_t)1 << 55) - 1);
+    entry->soft_dirty = (data >> 55) & 1;
+    entry->file_page = (data >> 61) & 1;
+    entry->swapped = (data >> 62) & 1;
+    entry->present = (data >> 63) & 1;
+    return 0;
+}
+
+/* Convert the given virtual address to physical using /proc/PID/pagemap.
+ *
+ * @param[out] paddr physical address
+ * @param[in]  pid   process to convert for
+ * @param[in] vaddr virtual address to get entry for
+ * @return 0 for success, 1 for failure
+ */
+int virt_to_phys_user(uintptr_t *paddr, uintptr_t vaddr)
+{
+    char pagemap_file[BUFSIZ];
+    int pagemap_fd;
+
+    snprintf(pagemap_file, sizeof(pagemap_file), "/proc/self/pagemap");
+    pagemap_fd = open(pagemap_file, O_RDONLY);
+    if (pagemap_fd < 0) {
+        return 1;
+    }
+    PagemapEntry entry;
+    if (pagemap_get_entry(&entry, pagemap_fd, vaddr)) {
+        return 1;
+    }
+    close(pagemap_fd);
+    *paddr = (entry.pfn * sysconf(_SC_PAGE_SIZE)) + (vaddr % sysconf(_SC_PAGE_SIZE));
+    return 0;
+}
+
+int main(void)
+{
+    printf("Allocating 1024 bytes as source\n");
+    uintptr_t src = (uintptr_t)malloc(1024);
+    printf("Virtual address: %lx\n", src);
+    uintptr_t src_phys;
+    virt_to_phys_user(&src_phys, src);
+    printf("Physical address: %lx\n", src_phys);
+    printf("\n\n");
+
+    printf("Allocating 1024 bytes as destination\n");
+    uintptr_t dst = (uintptr_t)malloc(1024);
+    printf("Virtual address: %lx\n", dst);
+    uintptr_t dst_phys;
+    virt_to_phys_user(&dst_phys, dst);
+    printf("Physical address: %lx\n", dst_phys);
+    printf("\n\n");
+
+    printf("mmaping PCIe space\n");
+    // this is hardcoded, seems to be deterministic.
+    uint32_t pcie_physical_base_offset = 0xfe800000;
+    int fd = open("/dev/mem", O_RDWR|O_SYNC);
+    uint32_t* pcie_base = (uint32_t*)mmap(0, 64, PROT_READ|PROT_WRITE, MAP_SHARED, fd, pcie_physical_base_offset);
+    uintptr_t pcie_physical_sanity_check;
+    virt_to_phys_user(&pcie_physical_sanity_check, (uintptr_t)pcie_base);
+    printf("Virtual PCIe Base: %p\n", pcie_base);
+    printf("Physical PCIe Base: %lx\n", pcie_physical_sanity_check);
+}