add vsyscall

- getcpu() is not implemented. It will cause SIGILL.
- gettimeofday() and time() are implemented with syscall.

arch/x86/kernel/memory.c

@@ -1698,6 +1698,21 @@ void init_low_area(struct page_table *pt)
 	set_pt_large_page(pt, 0, 0, PTATTR_WRITABLE);
 }
 
+static void init_vsyscall_area(struct page_table *pt)
+{
+	extern char vsyscall_page[];
+	int error;
+
+#define	VSYSCALL_ADDR	((void *)(0xffffffffff600000))
+	error = __set_pt_page(pt, VSYSCALL_ADDR,
+			virt_to_phys(vsyscall_page), PTATTR_ACTIVE|PTATTR_USER);
+	if (error) {
+		panic("init_vsyscall_area:__set_pt_page failed");
+	}
+
+	return;
+}
+
 void init_page_table(void)
 {
 #ifdef USE_LARGE_PAGES
@@ -1712,6 +1727,7 @@ void init_page_table(void)
 	init_fixed_area(init_pt);
 	init_low_area(init_pt);
 	init_text_area(init_pt);
+	init_vsyscall_area(init_pt);
 
 	load_page_table(init_pt);
 	kprintf("Page table is now at %p\n", init_pt);

arch/x86/kernel/vsyscall.c

@@ -0,0 +1,60 @@
+/**
+ * \file vsyscall.c
+ *  License details are found in the file LICENSE.
+ * \brief
+ *  implements x86's vsyscall
+ * \author Gou Nakamura  <go.nakamura.yw@hitachi-solutions.com> \par
+ * 	Copyright (C) 2014  Hitachi, Ltd.
+ */
+/*
+ * HISTORY:
+ */
+
+/*
+ * .vsyscall.* section's LMAs are different from their VMA.
+ * make sure that these are position-independent codes.
+ */
+
+#include <syscall.h>
+
+extern int vsyscall_gettimeofday(void *tv, void *tz)
+	__attribute__ ((section (".vsyscall.gettimeofday")));
+
+int vsyscall_gettimeofday(void *tv, void *tz)
+{
+	int error;
+
+	asm ("syscall" : "=a" (error)
+			: "a" (__NR_gettimeofday), "D" (tv), "S" (tz)
+			: "%rcx", "%r11", "memory");
+
+	return error;
+}
+
+extern long vsyscall_time(void *tp)
+	__attribute__ ((section (".vsyscall.time")));
+
+long vsyscall_time(void *tp)
+{
+	long t;
+
+	asm (		"syscall	;"
+			/*
+			 * This vsyscall_time() cannot fail, because glibc's
+			 * vsyscall_time() does not set the errno.
+			 *
+			 * Because a possible error is only a memory access error,
+			 * in order that this function generates SIGSEGV
+			 * rather than returns error when a memory access error occurs,
+			 * this function accesses memory in user mode.
+			 */
+			"test	%%rdx,%%rdx;"
+			"jz	1f;"
+			"mov	%%rax,(%%rdx);"
+			"1:"
+			: "=a" (t)
+			: "a" (__NR_time), "d" (tp), "D" (0)
+			: "%rcx", "%r11", "memory");
+
+	return t;
+}

kernel/config/attached-mic.lds

@@ -20,6 +20,19 @@ SECTIONS
 	.rodata : {
 	      *(.rodata .rodata.*)
 	} :data
+
+	.vsyscall : ALIGN(0x1000) {
+		vsyscall_page = .;
+
+		. = vsyscall_page + 0x000;
+		*(.vsyscall.gettimeofday)
+
+		. = vsyscall_page + 0x400;
+		*(.vsyscall.time)
+
+		. = ALIGN(4096);
+	} : data = 0xf4
+
     .bss : {
           *(.bss .bss.*)
     }

kernel/config/builtin-mic.lds

@@ -20,6 +20,19 @@ SECTIONS
 	.rodata : {
 	      *(.rodata .rodata.*)
 	} :data
+
+	.vsyscall : ALIGN(0x1000) {
+		vsyscall_page = .;
+
+		. = vsyscall_page + 0x000;
+		*(.vsyscall.gettimeofday)
+
+		. = vsyscall_page + 0x400;
+		*(.vsyscall.time)
+
+		. = ALIGN(4096);
+	} : data = 0xf4
+
     .bss : {
           *(.bss .bss.*)
     }

kernel/config/builtin-x86.lds

@@ -20,6 +20,19 @@ SECTIONS
 	.rodata : {
 	      *(.rodata .rodata.*)
 	} :data
+
+	.vsyscall : ALIGN(0x1000) {
+		vsyscall_page = .;
+
+		. = vsyscall_page + 0x000;
+		*(.vsyscall.gettimeofday)
+
+		. = vsyscall_page + 0x400;
+		*(.vsyscall.time)
+
+		. = ALIGN(4096);
+	} : data = 0xf4
+
     .bss : {
           *(.bss .bss.*)
     }

kernel/include/syscall.h

@@ -13,6 +13,7 @@
 #ifndef __HEADER_SYSCALL_H
 #define __HEADER_SYSCALL_H
 
+#include <ihk/context.h>
 #include <ihk/memconst.h>
 
 #define NUM_SYSCALLS 255