pagemap_dump!

kernel_module/user/usermem.c

@@ -0,0 +1,69 @@
+/*
+Only tested in x86_64.
+
+Provide an allocated userland memory address for us to test out kernel memory APIs, including:
+
+- /proc/pid/maps
+- /proc/pid/pagemap
+- /dev/mem
+
+Usage:
+
+	/usermem.out &
+
+Outputs address and pid, e.g.:
+
+	address 0x600800
+	pid 110
+
+Now translate the virtual address to physical for the given PID:
+
+	/pagemap2.out 110 | grep 0x600000
+
+where 0x600000 is the page that contains 0x600800.
+
+This produces a line of type:
+
+	0x600000 0x7c7b 0 0 0 1 /pagemap_test.out
+
+where 0x7c7b is the PFN. To get the physical address, just add three zeros back:
+
+	0x7c7b000
+
+Examine the physical memory from the QEMU monitor: on host:
+
+	./qemumonitor
+	xp 0x7c7b800
+
+Output:
+
+	0000000007c7b800: 0x12345678
+
+Yes!!! We read the correct value from the physical address.
+
+TODO: why does:
+
+	devmem2 0x7c7b800
+
+fail on the mmap? CONFIG_STRICT_DEVMEM is not set.
+*/
+
+#define _XOPEN_SOURCE 700
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+enum { I0 = 0x12345678 };
+
+static volatile uint32_t i = I0;
+
+int main(void) {
+	printf("address %p\n", (void *)&i);
+	printf("pid %ju\n", (uintmax_t)getpid());
+	while (i == I0) {
+		sleep(1);
+	}
+	printf("i %jx\n", (uintmax_t)i);
+	return EXIT_SUCCESS;
+}