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[XEN PATCH v1 1/4] arch/riscv: initial RISC-V support to build/run minimal Xen



The patch provides a minimal amount of changes to start
build and run minimal Xen binary at GitLab CI&CD that will
allow continuous checking of the build status of RISC-V Xen.

RISC-V Xen can be built by the following instructions:
  $ CONTAINER=riscv64 ./automation/scripts/containerize \
       make XEN_TARGET_ARCH=riscv64 tiny64_defconfig
  $ CONTAINER=riscv64 ./automation/scripts/containerize \
       make XEN_TARGET_ARCH=riscv64 -C xen build

RISC-V Xen can be run as:
  $ qemu-system-riscv64 -M virt -smp 1 -nographic -m 2g \
       -kernel xen/xen

To run in debug mode should be done the following instructions:
 $ qemu-system-riscv64 -M virt -smp 1 -nographic -m 2g \
        -kernel xen/xen -s -S
 # In separate terminal:
 $ riscv64-buildroot-linux-gnu-gdb
 $ target remote :1234
 $ add-symbol-file <xen_src>/xen/xen-syms 0x80200000
 $ hb *0x80200000
 $ c # it should stop at instruction j 0x80200000 <start>

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/riscv/Makefile             | 30 +++++++++++++
 xen/arch/riscv/arch.mk              | 10 +++++
 xen/arch/riscv/include/asm/config.h | 26 ++++++++++-
 xen/arch/riscv/include/asm/types.h  | 11 +++++
 xen/arch/riscv/riscv64/Makefile     |  2 +-
 xen/arch/riscv/riscv64/head.S       |  2 +-
 xen/arch/riscv/xen.lds.S            | 69 +++++++++++++++++++++++++++++
 7 files changed, 147 insertions(+), 3 deletions(-)
 create mode 100644 xen/arch/riscv/include/asm/types.h
 create mode 100644 xen/arch/riscv/xen.lds.S

diff --git a/xen/arch/riscv/Makefile b/xen/arch/riscv/Makefile
index 942e4ffbc1..893dd19ea6 100644
--- a/xen/arch/riscv/Makefile
+++ b/xen/arch/riscv/Makefile
@@ -1,2 +1,32 @@
+obj-$(CONFIG_RISCV_64) += riscv64/
+
+$(TARGET): $(TARGET)-syms
+       $(OBJCOPY) -O binary -S $< $@
+
+$(TARGET)-syms: $(objtree)/prelink.o $(obj)/xen.lds
+       $(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds -N $< \
+               $(SYMBOLS_DUMMY_OBJ) -o $(@D)/.$(@F).0
+       $(NM) -pa --format=sysv $(@D)/.$(@F).0 \
+               | $(objtree)/tools/symbols $(all_symbols) --sysv --sort 
>$(@D)/.$(@F).0.S
+       $(MAKE) $(build)=$(@D) $(@D)/.$(@F).0.o
+       $(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds -N $< \
+               $(@D)/.$(@F).0.o -o $(@D)/.$(@F).1
+       $(NM) -pa --format=sysv $(@D)/.$(@F).1 \
+               | $(objtree)/tools/symbols $(all_symbols) --sysv --sort 
>$(@D)/.$(@F).1.S
+       $(MAKE) $(build)=$(@D) $(@D)/.$(@F).1.o
+       $(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds -N $< $(build_id_linker) \
+               $(@D)/.$(@F).1.o -o $@
+       $(NM) -pa --format=sysv $(@D)/$(@F) \
+               | $(objtree)/tools/symbols --all-symbols --xensyms --sysv 
--sort \
+               >$(@D)/$(@F).map
+       rm -f $(@D)/.$(@F).[0-9]*
+
+$(obj)/xen.lds: $(src)/xen.lds.S FORCE
+               $(call if_changed_dep,cpp_lds_S)
+
+.PHONY: clean
+clean::
+       rm -f $(objtree)/.xen-syms.[0-9]*
+
 .PHONY: include
 include:
diff --git a/xen/arch/riscv/arch.mk b/xen/arch/riscv/arch.mk
index ae8fe9dec7..9292b72718 100644
--- a/xen/arch/riscv/arch.mk
+++ b/xen/arch/riscv/arch.mk
@@ -11,3 +11,13 @@ riscv-march-$(CONFIG_RISCV_ISA_C)       := $(riscv-march-y)c
 # -mcmodel=medlow would force Xen into the lower half.
 
 CFLAGS += -march=$(riscv-march-y) -mstrict-align -mcmodel=medany
+
+# TODO: Drop override and SYMBOLS_DUMMY_OBJ when more
+# of the build is working
+override ALL_OBJS-y = arch/$(TARGET_ARCH)/built_in.o
+override ALL_LIBS-y =
+ifneq ($(wildcard $(objtree)/common/symbols-dummy.o),)
+SYMBOLS_DUMMY_OBJ=$(objtree)/common/symbols-dummy.o
+else
+SYMBOLS_DUMMY_OBJ=
+endif
diff --git a/xen/arch/riscv/include/asm/config.h 
b/xen/arch/riscv/include/asm/config.h
index e2ae21de61..756607a4a2 100644
--- a/xen/arch/riscv/include/asm/config.h
+++ b/xen/arch/riscv/include/asm/config.h
@@ -28,7 +28,7 @@
 
 /* Linkage for RISCV */
 #ifdef __ASSEMBLY__
-#define ALIGN .align 2
+#define ALIGN .align 4
 
 #define ENTRY(name)                                \
   .globl name;                                     \
@@ -36,6 +36,30 @@
   name:
 #endif
 
+/*
+ * Definition of XEN_VIRT_START should look like:
+ *   define XEN_VIRT_START _AT(vaddr_t,0x00200000)
+ * It requires including of additional headers which
+ * will increase an amount of files unnecessary for
+ * minimal RISC-V Xen build so set value of
+ * XEN_VIRT_START explicitly.
+ *
+ * TODO: change it to _AT(vaddr_t,0x00200000) when
+ *       necessary header will be pushed.
+ */
+#define XEN_VIRT_START  0x80200000
+/*
+ * PAGE_SIZE is defined in <{asm,xen}/page-*.h> but to
+ * remove unnecessary headers for minimal
+ * build headers it will be better to set PAGE_SIZE
+ * explicitly.
+ *
+ * TODO: remove it when <asm/page-*.h> will be needed
+ *       defintion of PAGE_SIZE should be remove from
+ *       this header.
+ */
+#define PAGE_SIZE       4096
+
 #endif /* __RISCV_CONFIG_H__ */
 /*
  * Local variables:
diff --git a/xen/arch/riscv/include/asm/types.h 
b/xen/arch/riscv/include/asm/types.h
new file mode 100644
index 0000000000..afbca6b15c
--- /dev/null
+++ b/xen/arch/riscv/include/asm/types.h
@@ -0,0 +1,11 @@
+#ifndef __TYPES_H__
+#define __TYPES_H__
+
+/*
+ *
+ * asm/types.h is required for xen-syms.S file which
+ * is produced by tools/symbols.
+ *
+ */
+
+#endif
diff --git a/xen/arch/riscv/riscv64/Makefile b/xen/arch/riscv/riscv64/Makefile
index 15a4a65f66..3340058c08 100644
--- a/xen/arch/riscv/riscv64/Makefile
+++ b/xen/arch/riscv/riscv64/Makefile
@@ -1 +1 @@
-extra-y += head.o
+obj-y += head.o
diff --git a/xen/arch/riscv/riscv64/head.S b/xen/arch/riscv/riscv64/head.S
index 0dbc27ba75..0330b29c01 100644
--- a/xen/arch/riscv/riscv64/head.S
+++ b/xen/arch/riscv/riscv64/head.S
@@ -1,6 +1,6 @@
 #include <asm/config.h>
 
-        .text
+        .section .text.header, "ax", %progbits
 
 ENTRY(start)
         j  start
diff --git a/xen/arch/riscv/xen.lds.S b/xen/arch/riscv/xen.lds.S
new file mode 100644
index 0000000000..60628b3856
--- /dev/null
+++ b/xen/arch/riscv/xen.lds.S
@@ -0,0 +1,69 @@
+#include <xen/xen.lds.h>
+
+#undef ENTRY
+#undef ALIGN
+
+OUTPUT_ARCH(riscv)
+ENTRY(start)
+
+PHDRS
+{
+  text PT_LOAD ;
+#if defined(BUILD_ID)
+  note PT_NOTE ;
+#endif
+}
+
+SECTIONS
+{
+  . = XEN_VIRT_START;
+  _start = .;
+  .text : {
+        _stext = .;
+       *(.text.header)
+       *(.text)
+       *(.gnu.warning)
+       . = ALIGN(POINTER_ALIGN);
+       _etext = .;
+  } :text
+
+    . = ALIGN(PAGE_SIZE);
+  .rodata : {
+        _srodata = .;
+       *(.rodata)
+       *(.rodata.*)
+       *(.data.rel.ro)
+       *(.data.rel.ro.*)
+  } :text
+
+#if defined(BUILD_ID)
+  . = ALIGN(4);
+  .note.gnu.build-id : {
+       __note_gnu_build_id_start = .;
+       *(.note.gnu.build-id)
+       __note_gnu_build_id_end = .;
+  } :note :text
+#endif
+
+  . = ALIGN(PAGE_SIZE);
+  .data : { /* Data */
+       *(.data .data.*)
+  } :text
+
+  . = ALIGN(PAGE_SIZE);
+  .bss : {
+       __bss_start = .;
+       *(.bss .bss.*)
+       . = ALIGN(POINTER_ALIGN);
+       __bss_end = .;
+  } :text
+  _end = . ;
+
+  DWARF2_DEBUG_SECTIONS
+
+  DISCARD_SECTIONS
+
+  STABS_DEBUG_SECTIONS
+
+  ELF_DETAILS_SECTIONS
+}
-- 
2.38.1




 


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