Generate syscall numbers and remove hand-written numbers

Now the only thing you need to do to create a new syscall is write the kernel function and put "//SYSCALL" immediately before it. There are only two places we depended on these #defines: forkt and initcode. We now declare symbolic constants for the syscall numbers in sysstubs, which makes forkt just work (though it gets filled in at link time instead of by the preprocessor). For initcode, we now link initcode against sysstubs so it can get these constants.

Generate syscall numbers and remove hand-written numbers
7770d60c · Austin Clements · 5ca8b8e0 · 7770d60c · 5ca8b8e0 · 7770d60c
--- a/bin/usertests.cc
+++ b/bin/usertests.cc
@@ -3,7 +3,6 @@
 #include "user.h"
 #include "fs.h"
 #include "fcntl.h"
-#include "syscall.h"
 #include "traps.h"
 #include "pthread.h"


--- a/include/syscall.h
+++ b/include/syscall.h
-// System call numbers
-#define SYS_fork    1
-#define SYS_exit    2
-#define SYS_wait    3
-#define SYS_pipe    4
-#define SYS_write   5
-#define SYS_read    6
-#define SYS_close   7
-#define SYS_kill    8
-#define SYS_exec    9
-#define SYS_openat 10
-#define SYS_mknod  11
-#define SYS_unlink 12
-#define SYS_fstat  13
-#define SYS_link   14
-#define SYS_mkdirat 15
-#define SYS_chdir  16
-#define SYS_dup    17
-#define SYS_getpid 18
-#define SYS_sbrk   19
-#define SYS_nsleep 20
-#define SYS_uptime 21
-#define SYS_map    22
-#define SYS_unmap  23
-#define SYS_halt   24
-#define SYS_socket 25
-#define SYS_bind   26
-#define SYS_listen 27
-#define SYS_accept 28
-#define SYS_pread  29
-#define SYS_async  30
-#define SYS_script 31
-#define SYS_setfs  32
-#define SYS_wqwait 33
-#define SYS_setaffinity 34
-#define SYS_futex 35
-#define SYS_ncount 36   /* total number of system calls */
--- a/kernel/Makefrag
+++ b/kernel/Makefrag
@@ -115,13 +115,18 @@ $(O)/kernel/%.o: lib/%.cc
 $(O)/kernel/incbin.o: ASFLAGS+=-DMAKE_OUT=$(O)
 $(O)/kernel/incbin.o: $(O)/kernel/initcode $(O)/kernel/bootother $(O)/fs.img

+# link initcode against sysstubs to get syscall numbers
 $(O)/kernel/initcode: TTEXT = 0x1000
+$(O)/kernel/initcode: LDEXTRA = $(O)/lib/sysstubs.o
+$(O)/kernel/initcode: $(O)/lib/sysstubs.o
+
 $(O)/kernel/bootother: TTEXT = 0x7000
+
 $(O)/kernel/%: kernel/%.S
 	@echo "  CC     $@"
 	$(Q)mkdir -p $(@D)
 	$(Q)$(CC) $(CFLAGS) -nostdinc -I. -c $< -o $@.o
-	$(Q)$(LD) $(LDFLAGS) -N -e start -Ttext $(TTEXT) -o $@.out $@.o
+	$(Q)$(LD) $(LDFLAGS) -N -e start -Ttext $(TTEXT) -o $@.out $@.o $(LDEXTRA)
 	$(Q)$(OBJCOPY) -S -O binary $@.out $@

 $(O)/kernel/asmdefines.S: kernel/asmdefines.c

--- a/kernel/initcode.S
+++ b/kernel/initcode.S
 # Initial process execs /init.

-#include "syscall.h"
 #include "traps.h"

 # exec(init, argv)

--- a/kernel/syscall.cc
+++ b/kernel/syscall.cc
@@ -6,7 +6,6 @@
 #include "queue.h"
 #include "proc.hh"
 #include "amd64.h"
-#include "syscall.h"
 #include "cpu.hh"
 #include "kmtrace.hh"


--- a/lib/uthread.S
+++ b/lib/uthread.S
-#include "syscall.h"
-#include "traps.h"
-
 # We assume that the kernel follows the amd64 ABI, but not
 # that it saves caller-saved registers.
 .globl forkt

--- a/tools/syscalls.py
+++ b/tools/syscalls.py
@@ -20,10 +20,9 @@ def main():
    for fname in args:
        syscalls.extend(parse(file(fname, "r")))

-    # Parse syscall numbers
-    nums = dict(re.findall("#define SYS_([^ ]*) +([0-9]+)", file("include/syscall.h").read()))
-    for syscall in syscalls:
-        syscall.num = int(nums[syscall.basename])
+    # Generate syscall numbers
+    for n, syscall in enumerate(syscalls):
+        syscall.num = n + 1

    # Output
    if options.kvectors:
@@ -51,6 +50,9 @@ def main():
        print
        for syscall in syscalls:
            print """\
+.globl SYS_%(uname)s
+SYS_%(uname)s = %(num)d
+
 .globl %(uname)s
 %(uname)s:
  movq $%(num)d, %%rax""" % syscall.__dict__