Fix ucore user app compiling on x86_64

Signed-off-by: Harry Chen <i@harrychen.xyz>

Makefile

@@ -37,13 +37,11 @@ rust:
 	@cp $(rust_bins) $(out_dir)/rust
 
 ucore:
-ifneq ($(arch), x86_64)
 	@echo Building ucore programs
 	@mkdir -p ucore/build
 	@cd ucore/build && cmake $(cmake_build_args) .. && make
 	@rm -rf $(out_dir)/ucore && mkdir -p $(out_dir)/ucore
 	@cp $(ucore_bin_path)/* $(out_dir)/ucore
-endif
 
 biscuit:
 ifneq ($(shell uname)-$(arch), Darwin-riscv64)

README.md

@@ -53,7 +53,7 @@ A rootfs is created at `build/$(arch)` and converted to `qcow2`.
 
 |                    | x86_64 | aarch64 | riscv32 | riscv64 | mipsel |
 | ------------------ | ------ | ------- | ------- | ------- | ------ |
-| ucore              | ❌     | ✅      | ✅     | ✅      | ✅    |
+| ucore              | ✅     | ✅      | ✅     | ✅      | ✅    |
 | rust               | ✅     | ✅      | ✅     | ✅      | ✅    |
 | biscuit            | ✅     | ✅      | ✅     | ✅      | ✅    |
 | nginx (linux only) | ✅     | ✅      | ✅     | ✅      | ✅    |

ucore/src/arch/x86_64/initcode.S

@@ -4,21 +4,13 @@ _start:
     # set ebp for backtrace
     movl $0x0, %ebp
 
-    # load argc and argv
-    movl (%esp), %ebx
-    lea 0x4(%esp), %ecx
-
-
     # move down the esp register
     # since it may cause page fault in backtrace
     subl $0x20, %esp
 
-    # save argc and argv on stack
-    pushl %ecx
-    pushl %ebx
-
     # call user-program function
+    # according to fastcall ABI, the first 6 parameters are in registes
+    # so we do not need to copy (argc, argv) as on i386
     call umain
-1:  jmp 1b