Update kernels1 code from lecture/pset

Author: kohler

kernels1/ABOUT.md

@@ -6,8 +6,8 @@ This is WeensyOS, a teaching operating system built for Harvard’s
 
 Quickstart: `make run` will run the OS using the [QEMU] emulator.
 
-Running the OS
---------------
+Make targets
+------------
 
 `make run` will run the OS. On Docker, the OS will run in your terminal
 window; on a Linux virtual machine, QEMU will open a new window. (`make
@@ -21,11 +21,14 @@ WeensyOS creates a debug log in `log.txt`. Run `make LOG=stdio run` to
 redirect the debug log to the standard output, or `make
 LOG=file:FILENAME run` to redirect it to `FILENAME`.
 
-Run `make D=1 run` to ask QEMU to print verbose information about interrupts
-and CPU resets to the standard error. This setting will also cause QEMU to
-quit after encountering a [triple fault][] (normally it will reboot).
+`make D=1 run` tells QEMU to print verbose information about interrupts and
+CPU resets to the file `qemu.log`. This setting will also cause QEMU to quit
+after encountering a [triple fault][] (normally it will reboot).
+
+`make run-PROGRAM` runs `p-PROGRAM.cc` as the first non-init process. The
+default is `allocators`, which runs four copies of `p-allocator.cc`.
 
-Finally, run `make clean` to clean up your directory.
+Finally, `make clean` cleans up your directory.
 
 Building
 --------
@@ -44,19 +47,23 @@ but only version 5 or later.
 
 3. Install Homebrew’s QEMU: `brew install qemu`
 
-4. Tap [Sergio Benitez’s collection of cross-compilers](https://github.com/SergioBenitez/homebrew-osxct): `brew tap SergioBenitez/osxct`
-
-5. Install the `x86_64-unknown-linux-gnu` cross-compiler toolchain: `brew install x86_64-unknown-linux-gnu`
+4. Install a collection of cross-compilers for x86-64 Linux. At time of
+   writing, [this
+   collection](https://github.com/messense/homebrew-macos-cross-toolchains):
+   works: `brew tap messense/homebrew-macos-cross-toolchains; brew install
+   x86_64-unknown-linux-gnu`
 
-6. Create a file `config.mk` in this directory containing this:
+5. Create a file `config.mk` in this directory containing this:
 
     ```make
     CCPREFIX=x86_64-unknown-linux-gnu-
-    HOSTCC=gcc-12
-    HOSTCXX=g++-12
+    HOSTCC=gcc-14
+    HOSTCXX=g++-14
     ```
 
-    (Do not `git add config.mk`: it is intended for local configuration.)
+    But do not add `config.mk` to your repository! It configures the
+    build for your working directory environment, and the grading
+    server (for instance) can’t use those settings.
 
 Troubleshooting
 ---------------
@@ -72,7 +79,8 @@ OS has become unresponsive).
   enter Docker via `../cs61-run-docker` before running `make stop`.
 
 * If QEMU is running in a terminal window (in Docker, for instance), then
-  press `Alt-2`. This will bring up the QEMU Monitor, which looks like this:
+  press `Alt-2` (or `Option-2`). This will bring up the QEMU Monitor, which
+  looks like this:
 
     ```
     compat_monitor0 console
@@ -85,9 +93,9 @@ OS has become unresponsive).
     command to restore it.
 
     If `Alt-2` does not work, you may need to configure your terminal to
-    properly send the Alt key. For instance, on Mac OS X’s Terminal, go to
-    Terminal > Preferences > Keyboard and select “Use Option as Meta key”. You
-    can also configure a special keyboard shortcut that sends the `Escape 2`
+    properly send the Alt key. For instance, on Mac OS X’s Terminal, go to the
+    Edit menu, select “Use Option as Meta key”, and press `Option-2`. You can
+    also configure a special keyboard shortcut that sends the `Escape 2`
     sequence.
 
 Run `make run-gdb` to start up the OS with support for GDB debugging.

kernels1/COPYRIGHT

@@ -1,7 +1,7 @@
 The files in this directory are:
 
 /*
- * Copyright (C) 2006-2022 Eddie Kohler
+ * Copyright (C) 2006-2024 Eddie Kohler
  * Copyright (C) 2005 Regents of the University of California
  * Copyright (C) 1997 Massachusetts Institute of Technology
  *

kernels1/GNUmakefile

@@ -1,9 +1,11 @@
 QEMUIMAGEFILES = weensyos.img
 all: $(QEMUIMAGEFILES)
+include build/flags.mk
 
 # Place local configuration options, such as `CC=clang`, in
 # `config.mk` so you don't have to list them every time.
--include config.mk
+CONFIG ?= config.mk
+-include $(CONFIG)
 
 # `$(V)` controls whether the makefiles print verbose commands (the shell
 # commands run by Make) or brief commands (like `COMPILE`).
@@ -31,7 +33,9 @@ NCPU = 1
 LOG ?= file:log.txt
 QEMUOPT = -net none -parallel $(LOG) -smp $(NCPU)
 ifeq ($(D),1)
-QEMUOPT += -d int,cpu_reset,guest_errors -no-reboot
+QEMUOPT += -d int,cpu_reset,guest_errors -no-reboot -D qemu.log
+else ifeq ($(D),2)
+QEMUOPT += -d guest_errors -no-reboot -D qemu.log
 endif
 ifneq ($(NOGDB),1)
 QEMUGDB ?= -gdb tcp::12949
@@ -40,6 +44,8 @@ ifeq ($(STOP),1)
 QEMUOPT += -S
 endif
 
+QEMURANDSEED := $(strip $(shell od -N8 -tu8 -An /dev/urandom))
+
 
 # Sets of object files
 
@@ -91,33 +97,33 @@ endif
 # How to make object files
 
 $(OBJDIR)/%.ko: %.cc $(KERNELBUILDSTAMPS)
-	$(call cxxcompile,$(KERNELCXXFLAGS) -O1 -DWEENSYOS_KERNEL -c $< -o $@,COMPILE $<)
+	$(call cxxcompile,-O1 $(KERNELCXXFLAGS) -DWEENSYOS_KERNEL -c $< -o $@,COMPILE $<)
 
 $(OBJDIR)/%.ko: %.S $(OBJDIR)/k-asm.h $(KERNELBUILDSTAMPS)
 	$(call assemble,-O2 -c $< -o $@,ASSEMBLE $<)
 
 $(OBJDIR)/boot.o: $(OBJDIR)/%.o: boot.cc $(KERNELBUILDSTAMPS)
-	$(call cxxcompile,$(CXXFLAGS) -Os -fomit-frame-pointer -DWEENSYOS_KERNEL -c $< -o $@,COMPILE $<)
+	$(call cxxcompile,-Os $(CXXFLAGS) -fomit-frame-pointer -c $< -o $@,COMPILE $<)
 
 $(OBJDIR)/bootentry.o: $(OBJDIR)/%.o: \
 	bootentry.S $(OBJDIR)/k-asm.h $(KERNELBUILDSTAMPS)
 	$(call assemble,-Os -fomit-frame-pointer -c $< -o $@,ASSEMBLE $<)
 
 $(OBJDIR)/%.uo: %.cc $(BUILDSTAMPS)
-	$(call cxxcompile,$(CXXFLAGS) -O1 -DWEENSYOS_PROCESS -c $< -o $@,COMPILE $<)
+	$(call cxxcompile,-O1 $(CXXFLAGS) -DWEENSYOS_PROCESS -c $< -o $@,COMPILE $<)
 
 $(OBJDIR)/%.uo: %.S $(OBJDIR)/u-asm.h $(BUILDSTAMPS)
 	$(call assemble,-O2 -c $< -o $@,ASSEMBLE $<)
 
 
 # How to make supporting source files
 
-$(OBJDIR)/k-asm.h: kernel.hh lib.hh types.h x86-64.h build/mkkernelasm.awk $(KERNELBUILDSTAMPS)
-	$(call cxxcompile,-dM -E kernel.hh | awk -f build/mkkernelasm.awk | sort > $@,CREATE $@)
+$(OBJDIR)/k-asm.h: $(KERNELBUILDSTAMPS)
+	$(call run,$(k_asm_h_input_command) | $(asm_h_build_command) > $@,CREATE $@)
 	@if test ! -s $@; then echo '* Error creating $@!' 1>&2; exit 1; fi
 
-$(OBJDIR)/u-asm.h: u-lib.hh lib.hh types.h x86-64.h build/mkkernelasm.awk $(BUILDSTAMPS)
-	$(call cxxcompile,-dM -E u-lib.hh | awk -f build/mkkernelasm.awk | sort > $@,CREATE $@)
+$(OBJDIR)/u-asm.h: $(BUILDSTAMPS)
+	$(call run,$(u_asm_h_input_command) | $(asm_h_build_command) > $@,CREATE $@)
 	@if test ! -s $@; then echo '* Error creating $@!' 1>&2; exit 1; fi
 
 $(OBJDIR)/k-firstprocess.h:
@@ -127,7 +133,7 @@ $(OBJDIR)/k-foreachimage.h: build/mkforeachimage.awk $(PROCESSES_BUILDSTAMP)
 	$(call run,awk -f build/mkforeachimage.awk -v processes="$(PROCESSES)" > $@,CREATE $@)
 
 $(OBJDIR)/firstprocess.gdb:
-	$(call run,if test "$(WEENSYOS_FIRST_PROCESS)" = allocators; then echo "add-symbol-file obj/p-allocator.full 0x100000"; echo "add-symbol-file obj/p-allocator2.full 0x140000"; echo "add-symbol-file obj/p-allocator3.full 0x180000"; echo "add-symbol-file obj/p-allocator4.full 0x1C0000"; else echo "add-symbol-file obj/p-$(WEENSYOS_FIRST_PROCESS).full 0x100000"; fi > $@,CREATE $@)
+	$(call run,if test "$(WEENSYOS_FIRST_PROCESS)" = friends; then echo "add-symbol-file obj/p-alice.full 0x100000"; echo "add-symbol-file obj/p-eve.full 0x140000"; else echo "add-symbol-file obj/p-$(WEENSYOS_FIRST_PROCESS).full 0x100000"; fi > $@,CREATE $@)
 
 $(OBJDIR)/k-hardware.ko: $(OBJDIR)/k-foreachimage.h
 
@@ -158,7 +164,7 @@ $(OBJDIR)/%: $(OBJDIR)/%.full
 	$(call run,$(QUIETOBJCOPY) -j .text -j .rodata -j .data -j .bss -j .ctors -j .init_array $<,STRIP,$@)
 
 $(OBJDIR)/bootsector: $(BOOT_OBJS) build/boot.ld
-	$(call link,-T build/boot.ld -o $@.full $(BOOT_OBJS),LINK)
+	$(call link,-T build/boot.ld -z noexecstack -o $@.full $(BOOT_OBJS),LINK)
 	$(call run,$(OBJDUMP) -C -S $@.full >$@.asm)
 	$(call run,$(NM) -n $@.full >$@.sym)
 	$(call run,$(OBJCOPY) -S -O binary -j .text $@.full $@)
@@ -167,19 +173,19 @@ $(OBJDIR)/bootsector: $(BOOT_OBJS) build/boot.ld
 # How to make host program for ensuring a loaded symbol table
 
 $(OBJDIR)/mkchickadeesymtab: build/mkchickadeesymtab.cc $(BUILDSTAMPS)
-	$(call run,$(HOSTCXX) $(CPPFLAGS) $(HOSTCXXFLAGS) $(DEPCFLAGS) -g -o $@,HOSTCOMPILE,$<)
+	$(call run,$(HOSTCXX) $(HOSTCPPFLAGS) $(HOSTCXXFLAGS) $(DEPCFLAGS) -g -o $@,HOSTCOMPILE,$<)
 
 
 # How to make host programs for constructing & checking file systems
 
 $(OBJDIR)/%.o: %.cc $(BUILDSTAMPS)
-	$(call run,$(HOSTCXX) $(CPPFLAGS) $(HOSTCXXFLAGS) $(DEPCFLAGS) -c -o $@,HOSTCOMPILE,$<)
+	$(call run,$(HOSTCXX) $(HOSTCPPFLAGS) $(HOSTCXXFLAGS) $(DEPCFLAGS) -c -o $@,HOSTCOMPILE,$<)
 
 $(OBJDIR)/%.o: build/%.cc $(BUILDSTAMPS)
-	$(call run,$(HOSTCXX) $(CPPFLAGS) $(HOSTCXXFLAGS) $(DEPCFLAGS) -c -o $@,HOSTCOMPILE,$<)
+	$(call run,$(HOSTCXX) $(HOSTCPPFLAGS) $(HOSTCXXFLAGS) $(DEPCFLAGS) -c -o $@,HOSTCOMPILE,$<)
 
 $(OBJDIR)/mkbootdisk: build/mkbootdisk.cc $(BUILDSTAMPS)
-	$(call run,$(HOSTCXX) $(CPPFLAGS) $(HOSTCXXFLAGS) $(DEPCFLAGS) -g -o $@,HOSTCOMPILE,$<)
+	$(call run,$(HOSTCXX) $(HOSTCPPFLAGS) $(HOSTCXXFLAGS) $(DEPCFLAGS) -g -o $@,HOSTCOMPILE,$<)
 
 
 weensyos.img: $(OBJDIR)/mkbootdisk $(OBJDIR)/bootsector $(OBJDIR)/kernel
@@ -219,7 +225,7 @@ run-gdb-$(RUNSUFFIX): run-gdb
 run-gdb-graphic-$(RUNSUFFIX): run-gdb-graphic
 run-gdb-console-$(RUNSUFFIX): run-gdb-console
 
-# Kill all my qemus
+# Stop all my qemus
 stop kill:
 	-killall -u $$(whoami) $(QEMU)
 	@sleep 0.2; if ps -U $$(whoami) | grep $(QEMU) >/dev/null; then killall -9 -u $$(whoami) $(QEMU); fi

kernels1/boot.cc

@@ -14,8 +14,8 @@
 //   the boot device (hard drive) into memory at address 0x7C00, and jumps to
 //   that address.
 //
-//   The boot loader is contained in bootstart.S and boot.c. Control starts
-//   in bootstart.S, which initializes the CPU and sets up a stack, then
+//   The boot loader is contained in bootentry.S and boot.cc. Control starts
+//   in bootentry.S, which initializes the CPU and sets up a stack, then
 //   transfers here. This code reads in the kernel image and calls the
 //   kernel.
 //
@@ -56,8 +56,9 @@ static void boot_readseg(uintptr_t dst, uint32_t src_sect,
 
     // jump to the kernel
     using kernel_entry_t = void (*)();
-    [[noreturn]] kernel_entry_t kernel_entry = (kernel_entry_t) ELFHDR->e_entry;
+    kernel_entry_t kernel_entry = (kernel_entry_t) ELFHDR->e_entry;
     kernel_entry();
+    __builtin_unreachable(); // tell compiler `kernel_entry` does not return
 }
 
 

kernels1/bootentry.S

@@ -7,7 +7,7 @@
 #   Then it jumps to address 0x7C00 and the OS starts running!
 #
 #   This file contains the code loaded at that address.
-#   The `boot_start` routine switches the CPU out of compatibility mode,
+#   The `boot_entry` routine switches the CPU out of compatibility mode,
 #   then calls `boot` from `boot.cc` to finish the booting process.
 #
 #   There is no need to understand this code in detail!
@@ -20,34 +20,35 @@
 # For Your Information: COMPATIBILITY MODES
 #
 #   The Intel x86 architecture has many compatibility modes, going back to
-#   the 8086, which supported only 16-bit addresses.  When the BIOS calls
-#   into the OS, it is running in the "most compatible" mode, 16-bit real
+#   the 8086, which supported only 16-bit addresses. In the CPU we expect,
+#   the BIOS starts the OS while running in the oldest mode, 16-bit real
 #   mode. The machine acts like addresses are only 16 bits long,
 #   there's no paging support, and there isn't even any support for
 #   user-mode applications. The following weird magic transitions the
 #   processor to 64-bit mode and sets up a page table suitable for initial
-#   kernel execution.
+#   kernel execution. More recent iterations of 64-bit processors boot
+#   directly into 64-bit mode.
 #
 ###############################################################################
 
 /* import constants from kernel.hh and x86-64.h */
 #include "obj/k-asm.h"
 
-.globl boot_start                               # Entry point
-boot_start:
+.globl boot_entry                       # Entry point
+boot_entry:
         .code16                         # This runs in real mode
         cli                             # Disable interrupts
         cld                             # String operations increment
 
         # All segments are initially 0.
         # Set up the stack pointer, growing downward from 0x7c00.
-        movw    $boot_start, %sp
+        movw    $boot_entry, %sp
 
 notify_bios64:
         # Notify the BIOS (the machine's firmware) to optimize itself
         # for x86-64 code. https://wiki.osdev.org/X86-64
         movw    $0xEC00, %ax
-        movw    $2, %dx
+        movw    $2, %bx
         int     $0x15
 
 init_boot_pagetable:

kernels1/build/boot.ld

@@ -1,6 +1,6 @@
 OUTPUT_FORMAT(elf64-x86-64)
 OUTPUT_ARCH(i386:x86-64)
-ENTRY(boot_start)
+ENTRY(boot_entry)
 
 SECTIONS {
     . = 0x7c00;

kernels1/build/findgcc.sh

@@ -1,7 +1,7 @@
 #! /bin/sh
 
-# Look for gcc-12 or gcc-11 or gcc-10 or gcc-9.
-wantv=9
+# Look for gcc-{14,9}; prefer gcc-12 or above
+wantv=12
 
 ver1 () {
     ( $1 -dumpversion 2>/dev/null || echo 0 ) | sed 's/[^0-9].*//'
@@ -12,7 +12,7 @@ if "$prog" -v 2>&1 | grep '^gcc' >/dev/null; then
     base=`echo "$prog" | sed 's/^\([^g]\)/g\1/'`
     v=`ver1 "$prog"`
     if [ $v -lt $wantv ]; then
-        for vx in 12 11 10 9; do
+        for vx in 14 13 12 11 10 9; do
             if [ `ver1 "$base-$vx"` -ge $wantv ]; then
                 echo "$base-$vx"; exit
             fi

kernels1/build/flags.mk

@@ -0,0 +1,29 @@
+# Initialize compiler flags so `config.mk` can augment them
+
+# Set up dependency files
+DEPCFLAGS = -MD -MF $(DEPSDIR)/$(@F).d -MP
+
+# Flags for building programs that run on the host (not in WeensyOS)
+HOSTCPPFLAGS = $(DEFS) -I.
+HOSTCFLAGS := $(CFLAGS) -std=gnu2x -Wall -W
+HOSTCXXFLAGS := $(CXXFLAGS) -std=gnu++2a -Wall -W
+
+# Flags for building WeensyOS kernel and process code
+CPPFLAGS = $(DEFS) -I.
+
+CCOMMONFLAGS := -m64 -mno-mmx -mno-sse -mno-sse2 -mno-sse3 \
+       -mno-3dnow -ffreestanding -fno-pic \
+       -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer \
+       -fno-stack-protector \
+       -Wall -W -Wshadow -Wno-format -Wno-unused-parameter
+
+CFLAGS := $(CFLAGS) $(CCOMMONFLAGS) -std=gnu2x -gdwarf-4
+
+CXXFLAGS := $(CXXFLAGS) $(CCOMMONFLAGS) -std=gnu++2a \
+       -fno-exceptions -fno-rtti -gdwarf-4 -ffunction-sections
+KERNELCXXFLAGS := $(CXXFLAGS) -mno-red-zone $(SANITIZEFLAGS)
+
+ASFLAGS := $(CCOMMONFLAGS)
+
+LDFLAGS := $(LDFLAGS) -Os --gc-sections -z max-page-size=0x1000 \
+	-z noexecstack -static -nostdlib

kernels1/build/process.ld

@@ -1,6 +1,6 @@
 OUTPUT_FORMAT(elf64-x86-64)
 OUTPUT_ARCH(i386:x86-64)
-ENTRY(_Z12process_mainv)
+ENTRY(process_main)
 
 PHDRS {
     text PT_LOAD;
@@ -19,17 +19,37 @@ SECTIONS {
         *(.text .stub .text.* .gnu.linkonce.t.*)
     } :text
     PROVIDE(etext = .);    /* Define the `etext` symbol at this location */
+
+    /* support several signatures for `process_main` */
+    process_main = (DEFINED(process_main) ? process_main
+        : DEFINED(_Z12process_mainiPPc) ? _Z12process_mainiPPc
+        : _Z12process_mainv);
+
     .rodata : {
         *(.rodata .rodata.* .gnu.linkonce.r.*)
         *(.data.rel.ro.local* .gnu.linkonce.d.rel.ro.local.*)
         *(.data.rel.ro .data.rel.ro.* .gnu.linkonce.d.rel.ro.*)
     } :text
 
+    /* Constructors: these sections support global initialization
+       functions, such as for global C++ objects with constructors. */
+    .init_array : {
+        PROVIDE(__init_array_start = .);
+        KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*)
+                SORT_BY_INIT_PRIORITY(.ctors.*)))
+        KEEP (*(.init_array .ctors))
+        PROVIDE(__init_array_end = .);
+    } :text
+    .ctors : {
+        KEEP (*crtbegin.o(.ctors))
+        KEEP (*(SORT(.ctors.*)))
+        KEEP (*(.ctors))
+    } :text
+
     /* Data segment: read/write and zero-initialized globals */
     . = ALIGN(4096);       /* Align to a page boundary */
     .data : {
         *(.data .data.* .gnu.linkonce.d.*)
-        SORT(CONSTRUCTORS)
     } :data
     PROVIDE(edata = .);
     .bss : {