move doc of userland physical address tests to README

kernel_module/user/README.adoc

@@ -1,6 +1,3 @@
 https://github.com/cirosantilli/linux-kernel-module-cheat#rootfs_overlay
 
 . link:sched_getaffinity.c[]
-. link:usermem.c[]
-.. link:pagemap_dump.c[]
-. link:uio_read.c[]

kernel_module/user/pagemap_dump.c

@@ -1,29 +1,4 @@
-/*
-Only tested in x86_64.
-
-Adapted from: https://github.com/dwks/pagemap/blob/8a25747bc79d6080c8b94eac80807a4dceeda57a/pagemap2.c
-
-- https://stackoverflow.com/questions/17021214/how-to-decode-proc-pid-pagemap-entries-in-linux/45126141#45126141
-- https://stackoverflow.com/questions/5748492/is-there-any-api-for-determining-the-physical-address-from-virtual-address-in-li
-- https://stackoverflow.com/questions/6284810/proc-pid-pagemaps-and-proc-pid-maps-linux/45500208#45500208
-
-Dump the page map of a given process PID.
-
-Data sources: /proc/PIC/{map,pagemap}
-
-This program works in two steps:
-
--   parse the human readable lines lines from `/proc/<pid>/maps`. This files contains lines of form:
-
-        7ffff7b6d000-7ffff7bdd000 r-xp 00000000 fe:00 658                        /lib/libuClibc-1.0.22.so
-
-    which gives us:
-
-    - `7f8af99f8000-7f8af99ff000`: a virtual address range that belong to the process, possibly containing multiple pages.
-    - `/lib/libuClibc-1.0.22.so` the name of the library that owns that memory.
-
--   loop over each page of each address range, and ask `/proc/<pid>/pagemap` for more information about that page, including the physical address.
-*/
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#pagemap_dump-out */
 
 #define _XOPEN_SOURCE 700
 #include <errno.h>
@@ -63,7 +38,7 @@ int main(int argc, char **argv)
 		perror("open pagemap");
 		return EXIT_FAILURE;
 	}
-	printf("addr pfn soft-dirty file/shared swapped present library\n");
+	printf("vaddr pfn soft-dirty file/shared swapped present library\n");
 	for (;;) {
 		ssize_t length = read(maps_fd, buffer + offset, sizeof buffer - offset);
 		if (length <= 0) break;
@@ -116,11 +91,11 @@ int main(int argc, char **argv)
 				/* Get info about all pages in this page range with pagemap. */
 				{
 					PagemapEntry entry;
-					for (uintptr_t addr = low; addr < high; addr += sysconf(_SC_PAGE_SIZE)) {
+					for (uintptr_t vaddr = low; vaddr < high; vaddr += sysconf(_SC_PAGE_SIZE)) {
 						/* TODO always fails for the last page (vsyscall), why? pread returns 0. */
-						if (!pagemap_get_entry(&entry, pagemap_fd, addr)) {
+						if (!pagemap_get_entry(&entry, pagemap_fd, vaddr)) {
 							printf("%jx %jx %u %u %u %u %s\n",
-								(uintmax_t)addr,
+								(uintmax_t)vaddr,
 								(uintmax_t)entry.pfn,
 								entry.soft_dirty,
 								entry.file_page,

kernel_module/user/usermem.c

@@ -1,91 +0,0 @@
-/*
-Only tested in x86_64.
-
-Provide an allocated userland memory for us to test out kernel memory APIs, including:
-
-- /proc/pid/maps
-- /proc/pid/pagemap. See also: https://stackoverflow.com/questions/17021214/decode-proc-pid-pagemap-entry/45126141#45126141
-- /dev/mem
-
-Usage:
-
-	/usermem.out &
-
-Outputs the virtual address and pid, e.g.:
-
-	vaddr 0x600800
-	pid 110
-
-Translate the virtual address to physical for the given PID:
-
-	/virt_to_phys_user.out 110 0x600800
-
-Sample output physical address:
-
-	0x7c7b800
-
-## QEMU monitor xp
-
-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.
-
-## /dev/mem
-
-Firt up, this requires:
-
-- CONFIG_STRICT_DEVMEM is not set.
-- nopat on kernel parameters
-
-see: https://stackoverflow.com/questions/11891979/how-to-access-mmaped-dev-mem-without-crashing-the-linux-kernel
-
-Then:
-
-	devmem 0x7c7b800
-
-Possible output:
-
-	Memory mapped at address 0x7ff7dbe01000.
-	Value at address 0X7C7B800 (0x7ff7dbe01800): 0x12345678
-
-where 0x7ff7dbe01000 is a new virtual address that was mapped
-to our physical address and given to the process that mapped /dev/mem.
-
-And finally, let's change the value!
-
-	devmem 0x7c7b800 w 0x9abcdef0
-
-After one second, we see on the screen:
-
-	i 9abcdef0
-	[1]+  Done                       /usermem.out
-
-so the while loop was exited!
-*/
-
-#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("vaddr %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;
-}

kernel_module/user/virt_to_phys_test.c

@@ -0,0 +1,21 @@
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#userland-physical-address-experiments */
+
+#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("vaddr %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;
+}

kernel_module/user/virt_to_phys_user.c

@@ -1,10 +1,4 @@
-/*
-Convert a virtual address to physical for a given process PID using /proc/PID/pagemap.
-
-https://stackoverflow.com/questions/5748492/is-there-any-api-for-determining-the-physical-address-from-virtual-address-in-li/45128487#45128487
-
-Test this out with usermem.c.
-*/
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#userland-physical-address-experiments */
 
 #define _XOPEN_SOURCE 700
 #include <stdio.h> /* printf */