vtp: add virt_to_phys lib

CMakeLists.txt

@@ -9,6 +9,7 @@ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Werror")
 
 include_directories(thirdparty/spdlog/include)
 
+add_subdirectory(vtp)
 add_subdirectory(lib)
 add_subdirectory(tests)
 

lib/CMakeLists.txt

@@ -34,7 +34,7 @@ find_package(Threads)
 
 add_library(villas-fpga SHARED ${SOURCES})
 
-target_link_libraries(villas-fpga PUBLIC villas-common)
+target_link_libraries(villas-fpga PUBLIC villas-common vtp)
 
 # GPU library is optional, check for CUDA presence
 include(CheckLanguage)

vtp/CMakeLists.txt

+cmake_minimum_required(VERSION 3.7)
+
+project(vtp C)
+
+#add_library(vtp_objects OBJECT virt_to_phys.c)
+#set_source_files_properties(virt_to_phys.c PROPERTIES COMPILE_FLAGS -fPIC)
+
+add_library(vtp SHARED virt_to_phys.c) #$<TARGET_OBJECTS:vtp_objects>)
+target_include_directories(vtp PUBLIC ${CMAKE_CURRENT_LIST_DIR})

vtp/virt_to_phys.c

+#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 */
+
+typedef struct {
+    uint64_t pfn : 54;
+    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;
+
+    nread = 0;
+    while (nread < sizeof(data)) {
+        ret = pread(pagemap_fd, &data, sizeof(data),
+                (vaddr / sysconf(_SC_PAGE_SIZE)) * sizeof(data) + nread);
+        nread += ret;
+        if (ret <= 0) {
+            return 1;
+        }
+    }
+    entry->pfn = data & (((uint64_t)1 << 54) - 1);
+    entry->soft_dirty = (data >> 54) & 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, pid_t pid, uintptr_t vaddr)
+{
+    char pagemap_file[BUFSIZ];
+    int pagemap_fd;
+
+    snprintf(pagemap_file, sizeof(pagemap_file), "/proc/%ju/pagemap", (uintmax_t)pid);
+    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 virt_to_phys(uintptr_t* paddr, uintptr_t vaddr)
+{
+	return virt_to_phys_user(paddr, getpid(), vaddr);
+}

vtp/virt_to_phys.h

+#pragma once
+
+#include <stdint.h>
+#include <fcntl.h>
+
+extern "C" {
+
+int virt_to_phys_user(uintptr_t *paddr, pid_t pid, uintptr_t vaddr);
+
+// for current process
+int virt_to_phys(uintptr_t* paddr, uintptr_t vaddr);
+
+}