patch-2.4.20 linux-2.4.20/arch/x86_64/kernel/vsyscall.c

• Lines: 162
• Date: Thu Nov 28 15:53:12 2002
• Orig file: linux-2.4.19/arch/x86_64/kernel/vsyscall.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/arch/x86_64/kernel/vsyscall.c linux-2.4.20/arch/x86_64/kernel/vsyscall.c
@@ -0,0 +1,161 @@
+/*
+ *  linux/arch/x86_64/kernel/vsyscall.c
+ *
+ *  Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
+ *
+ *  Thanks to hpa@transmeta.com for some useful hint.
+ *  Special thanks to Ingo Molnar for his early experience with
+ *  a different vsyscall implementation for Linux/IA32 and for the name.
+ *
+ *  vsyscall 1 is located at -10Mbyte, vsyscall 2 is located
+ *  at virtual address -10Mbyte+1024bytes etc... There are at max 8192
+ *  vsyscalls. One vsyscall can reserve more than 1 slot to avoid
+ *  jumping out of line if necessary.
+ *
+ *  $Id: vsyscall.c,v 1.19 2002/07/19 02:24:08 vojtech Exp $
+ */
+
+/*
+ * TODO 2001-03-20:
+ *
+ * 1) make page fault handler detect faults on page1-page-last of the vsyscall
+ *    virtual space, and make it increase %rip and write -ENOSYS in %rax (so
+ *    we'll be able to upgrade to a new glibc without upgrading kernel after
+ *    we add more vsyscalls.
+ * 2) Possibly we need a fixmap table for the vsyscalls too if we want
+ *    to avoid SIGSEGV and we want to return -EFAULT from the vsyscalls as well.
+ *    Can we segfault inside a "syscall"? We can fix this anytime and those fixes
+ *    won't be visible for userspace. Not fixing this is a noop for correct programs,
+ *    broken programs will segfault and there's no security risk until we choose to
+ *    fix it.
+ *
+ * These are not urgent things that we need to address only before shipping the first
+ * production binary kernels.
+ */
+
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+
+#include <asm/vsyscall.h>
+#include <asm/pgtable.h>
+#include <asm/page.h>
+#include <asm/fixmap.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+#include <asm/msr.h>
+
+#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
+
+long __vxtime_sequence[2] __section_vxtime_sequence;
+
+#undef USE_VSYSCALL
+
+#ifdef USE_VSYSCALL
+
+static inline void do_vgettimeofday(struct timeval * tv)
+{
+	long sequence, t;
+	unsigned long sec, usec;
+
+	do {
+		sequence = __vxtime_sequence[1];
+		rmb();
+
+		rdtscll(t);
+		sec = __xtime.tv_sec;
+		usec = __xtime.tv_usec +
+			(__jiffies - __wall_jiffies) * (1000000 / HZ) +
+			(t  - __hpet.last_tsc) * (1000000 / HZ) / __hpet.ticks + __hpet.offset;
+
+		rmb();
+	} while (sequence != __vxtime_sequence[0]);
+
+	tv->tv_sec = sec + usec / 1000000;
+	tv->tv_usec = usec % 1000000;
+}
+
+static inline void do_get_tz(struct timezone * tz)
+{
+	long sequence;
+
+	do {
+		sequence = __vxtime_sequence[1];
+		rmb();
+
+		*tz = __sys_tz;
+
+		rmb();
+	} while (sequence != __vxtime_sequence[0]);
+}
+
+static long __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
+{
+	if (tv) do_vgettimeofday(tv);
+	if (tz) do_get_tz(tz);
+	return 0;
+}
+
+#else
+
+#include <asm/unistd.h>
+
+static long __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
+{
+	int r;
+	asm volatile("syscall"
+		     : "=a" (r)
+		     : "0" (__NR_gettimeofday), "D" (tv), "S" (tz)
+		     : "r11", "rcx","memory");
+	return r;
+}
+
+#endif
+
+static time_t __vsyscall(1) vtime(time_t * tp)
+{
+	struct timeval tv;
+	vgettimeofday(&tv, NULL);
+	if (tp) *tp = tv.tv_sec;
+	return tv.tv_sec;
+}
+
+static long __vsyscall(2) venosys_0(void)
+{
+	return -ENOSYS;
+}
+
+static long __vsyscall(3) venosys_1(void)
+{
+	return -ENOSYS;
+}
+
+static void __init map_vsyscall(void)
+{
+	extern char __vsyscall_0;
+	unsigned long physaddr_page0 = (unsigned long) &__vsyscall_0 - __START_KERNEL_map;
+
+	__set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
+	if (hpet.address)
+		__set_fixmap(VSYSCALL_HPET, hpet.address, PAGE_KERNEL_VSYSCALL);
+}
+
+static int __init vsyscall_init(void)
+{
+	printk("VSYSCALL: consistency checks...");
+	if ((unsigned long) &vgettimeofday != VSYSCALL_ADDR(__NR_vgettimeofday))
+		panic("vgettimeofday link addr broken");
+	if ((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime))
+		panic("vtime link addr broken");
+	if (VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE))
+		panic("fixmap first vsyscall %lx should be %lx", __fix_to_virt(VSYSCALL_FIRST_PAGE),
+			VSYSCALL_ADDR(0));
+	printk("passed...mapping...");
+	map_vsyscall();
+	printk("done.\n");
+
+	return 0;
+}
+
+__initcall(vsyscall_init);