lkmc v2-rc

Unsquashed version at v2-rc-unsquashed, but that cannot be merged as it
breaks bisects at several points. All bugs will not bisect to this
humongous change.

It all started with a conversion of the Bash scripts to Python, mainly
because I couldn't stand not being able to properly use --options for
run which has a million options.

Then since that required a full testing, I decided to do all the
refactorings that I had in mind at once, and so I did and it became
v2-rc.

This is the largest patch I have ever done! OMG a few weeks of extra time.
I'm never writing a Bash script for anything that starts getting big again.

Some of the features are:

* separate build-qemu and build-gem5 commands
* common: convert scripts to python. Add --option for everything
* rename build to build-buildroot now that we are splitting all the build
  commands, Linux kernel to follow
* move all git submodules to submodules/ and all buildroot packages to
  packages/
* refactor the out/ structure. Keep projects on toplevel, because guest
  projects separate archs and host ones don't, making a toplevel arch wrong
* do-release: rename to just release
  https://stackoverflow.com/questions/16174992/cant-get-argparse-to-read-quoted-string-with-dashes-in-it
* run: add --terminal and explain gem5 pdb
* just track the lvimrc
* store CLI kernel config fragment inside buildlroot to avoid conflicts
* gem5: document m5 initparam
* readme: make a bunch of things awesomer
* readme: fix broken refs
* parsec-benchmark: update to 75d55ac446a43c47efb1044844a108c6c330184c
  Could not fetch otherwise.
* gem5: M5_OVERRIDE_PY_SOURCE

packages/kernel_modules/user/pagemap_dump.c

@@ -0,0 +1,116 @@
+/* https://github.com/cirosantilli/linux-kernel-module-cheat#pagemap_dump-out */
+
+#define _XOPEN_SOURCE 700
+#include <errno.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "common.h" /* pagemap_get_entry */
+
+int main(int argc, char **argv)
+{
+	char buffer[BUFSIZ];
+	char maps_file[BUFSIZ];
+	char pagemap_file[BUFSIZ];
+	int maps_fd;
+	int offset = 0;
+	int pagemap_fd;
+	pid_t pid;
+
+	if (argc < 2) {
+		printf("Usage: %s pid\n", argv[0]);
+		return EXIT_FAILURE;
+	}
+	pid = strtoull(argv[1], NULL, 0);
+	snprintf(maps_file, sizeof(maps_file), "/proc/%ju/maps", (uintmax_t)pid);
+	snprintf(pagemap_file, sizeof(pagemap_file), "/proc/%ju/pagemap", (uintmax_t)pid);
+	maps_fd = open(maps_file, O_RDONLY);
+	if (maps_fd < 0) {
+		perror("open maps");
+		return EXIT_FAILURE;
+	}
+	pagemap_fd = open(pagemap_file, O_RDONLY);
+	if (pagemap_fd < 0) {
+		perror("open pagemap");
+		return EXIT_FAILURE;
+	}
+	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;
+		length += offset;
+		for (size_t i = offset; i < (size_t)length; i++) {
+			uintptr_t low = 0, high = 0;
+			if (buffer[i] == '\n' && i) {
+				const char *lib_name;
+				size_t y;
+				/* Parse a line from maps. Each line contains a range that contains many pages. */
+				{
+					size_t x = i - 1;
+					while (x && buffer[x] != '\n') x--;
+					if (buffer[x] == '\n') x++;
+					while (buffer[x] != '-' && x < sizeof buffer) {
+						char c = buffer[x++];
+						low *= 16;
+						if (c >= '0' && c <= '9') {
+							low += c - '0';
+						} else if (c >= 'a' && c <= 'f') {
+							low += c - 'a' + 10;
+						} else {
+						    break;
+						}
+					}
+					while (buffer[x] != '-' && x < sizeof buffer) x++;
+					if (buffer[x] == '-') x++;
+					while (buffer[x] != ' ' && x < sizeof buffer) {
+						char c = buffer[x++];
+						high *= 16;
+						if (c >= '0' && c <= '9') {
+							high += c - '0';
+						} else if (c >= 'a' && c <= 'f') {
+							high += c - 'a' + 10;
+						} else {
+							break;
+						}
+					}
+					lib_name = 0;
+					for (int field = 0; field < 4; field++) {
+						x++;
+						while(buffer[x] != ' ' && x < sizeof buffer) x++;
+					}
+					while (buffer[x] == ' ' && x < sizeof buffer) x++;
+					y = x;
+					while (buffer[y] != '\n' && y < sizeof buffer) y++;
+					buffer[y] = 0;
+					lib_name = buffer + x;
+				}
+				/* Get info about all pages in this page range with pagemap. */
+				{
+					PagemapEntry entry;
+					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, vaddr)) {
+							printf("%jx %jx %u %u %u %u %s\n",
+								(uintmax_t)vaddr,
+								(uintmax_t)entry.pfn,
+								entry.soft_dirty,
+								entry.file_page,
+								entry.swapped,
+								entry.present,
+								lib_name
+							);
+						}
+					}
+				}
+				buffer[y] = '\n';
+			}
+		}
+	}
+	close(maps_fd);
+	close(pagemap_fd);
+	return EXIT_SUCCESS;
+}