* 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
+ * at virtual address -10Mbyte+1024bytes etc... There are at max 4
* vsyscalls. One vsyscall can reserve more than 1 slot to avoid
- * jumping out of line if necessary.
+ * jumping out of line if necessary. We cannot add more with this
+ * mechanism because older kernels won't return -ENOSYS.
+ * If we want more than four we need a vDSO.
*
- * Note: the concept clashes with user mode linux. If you use UML just
- * set the kernel.vsyscall sysctl to 0.
- */
-
-/*
- * 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.
+ * Note: the concept clashes with user mode linux. If you use UML and
+ * want per guest time just set the kernel.vsyscall64 sysctl to 0.
*/
#include <linux/time.h>
#include <linux/timer.h>
#include <linux/seqlock.h>
#include <linux/jiffies.h>
+#include <linux/sysctl.h>
+#include <linux/getcpu.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/notifier.h>
#include <asm/vsyscall.h>
#include <asm/pgtable.h>
#include <asm/fixmap.h>
#include <asm/errno.h>
#include <asm/io.h>
+#include <asm/segment.h>
+#include <asm/desc.h>
+#include <asm/topology.h>
#define __vsyscall(nr) __attribute__ ((unused,__section__(".vsyscall_" #nr)))
-#define force_inline __attribute__((always_inline)) inline
+#define __syscall_clobber "r11","rcx","memory"
int __sysctl_vsyscall __section_sysctl_vsyscall = 1;
seqlock_t __xtime_lock __section_xtime_lock = SEQLOCK_UNLOCKED;
+int __vgetcpu_mode __section_vgetcpu_mode;
#include <asm/unistd.h>
-static force_inline void timeval_normalize(struct timeval * tv)
+static __always_inline void timeval_normalize(struct timeval * tv)
{
time_t __sec;
__sec = tv->tv_usec / 1000000;
- if (__sec)
- {
+ if (__sec) {
tv->tv_usec %= 1000000;
tv->tv_sec += __sec;
}
}
-static force_inline void do_vgettimeofday(struct timeval * tv)
+static __always_inline void do_vgettimeofday(struct timeval * tv)
{
long sequence, t;
unsigned long sec, usec;
sequence = read_seqbegin(&__xtime_lock);
sec = __xtime.tv_sec;
- usec = (__xtime.tv_nsec / 1000) +
- (__jiffies - __wall_jiffies) * (1000000 / HZ);
+ usec = __xtime.tv_nsec / 1000;
- if (__vxtime.mode == VXTIME_TSC) {
- sync_core();
- rdtscll(t);
- if (t < __vxtime.last_tsc) t = __vxtime.last_tsc;
+ if (__vxtime.mode != VXTIME_HPET) {
+ t = get_cycles_sync();
+ if (t < __vxtime.last_tsc)
+ t = __vxtime.last_tsc;
usec += ((t - __vxtime.last_tsc) *
__vxtime.tsc_quot) >> 32;
- /* See comment in x86_64 do_gettimeofday. */
+ /* See comment in x86_64 do_gettimeofday. */
} else {
- usec += ((readl((void *)fix_to_virt(VSYSCALL_HPET) + 0xf0) -
+ usec += ((readl((void __iomem *)
+ fix_to_virt(VSYSCALL_HPET) + 0xf0) -
__vxtime.last) * __vxtime.quot) >> 32;
}
} while (read_seqretry(&__xtime_lock, sequence));
}
/* RED-PEN may want to readd seq locking, but then the variable should be write-once. */
-static force_inline void do_get_tz(struct timezone * tz)
+static __always_inline void do_get_tz(struct timezone * tz)
{
- *tz = __sys_tz;
+ *tz = __sys_tz;
}
-
-static force_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
+static __always_inline int gettimeofday(struct timeval *tv, struct timezone *tz)
{
int ret;
- asm volatile("syscall"
+ asm volatile("vsysc2: syscall"
: "=a" (ret)
: "0" (__NR_gettimeofday),"D" (tv),"S" (tz) : __syscall_clobber );
return ret;
}
-static force_inline long time_syscall(long *t)
+static __always_inline long time_syscall(long *t)
{
long secs;
- asm volatile("syscall"
+ asm volatile("vsysc1: syscall"
: "=a" (secs)
: "0" (__NR_time),"D" (t) : __syscall_clobber);
return secs;
}
-static int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
+int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz)
{
- if (unlikely(!__sysctl_vsyscall))
- return gettimeofday(tv,tz);
+ if (!__sysctl_vsyscall)
+ return gettimeofday(tv,tz);
if (tv)
do_vgettimeofday(tv);
if (tz)
/* This will break when the xtime seconds get inaccurate, but that is
* unlikely */
-static time_t __vsyscall(1) vtime(time_t *t)
+time_t __vsyscall(1) vtime(time_t *t)
{
- if (unlikely(!__sysctl_vsyscall))
+ if (!__sysctl_vsyscall)
return time_syscall(t);
else if (t)
*t = __xtime.tv_sec;
return __xtime.tv_sec;
}
-static long __vsyscall(2) venosys_0(void)
+/* Fast way to get current CPU and node.
+ This helps to do per node and per CPU caches in user space.
+ The result is not guaranteed without CPU affinity, but usually
+ works out because the scheduler tries to keep a thread on the same
+ CPU.
+
+ tcache must point to a two element sized long array.
+ All arguments can be NULL. */
+long __vsyscall(2)
+vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
+{
+ unsigned int dummy, p;
+ unsigned long j = 0;
+
+ /* Fast cache - only recompute value once per jiffies and avoid
+ relatively costly rdtscp/cpuid otherwise.
+ This works because the scheduler usually keeps the process
+ on the same CPU and this syscall doesn't guarantee its
+ results anyways.
+ We do this here because otherwise user space would do it on
+ its own in a likely inferior way (no access to jiffies).
+ If you don't like it pass NULL. */
+ if (tcache && tcache->blob[0] == (j = __jiffies)) {
+ p = tcache->blob[1];
+ } else if (__vgetcpu_mode == VGETCPU_RDTSCP) {
+ /* Load per CPU data from RDTSCP */
+ rdtscp(dummy, dummy, p);
+ } else {
+ /* Load per CPU data from GDT */
+ asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
+ }
+ if (tcache) {
+ tcache->blob[0] = j;
+ tcache->blob[1] = p;
+ }
+ if (cpu)
+ *cpu = p & 0xfff;
+ if (node)
+ *node = p >> 12;
+ return 0;
+}
+
+long __vsyscall(3) venosys_1(void)
{
return -ENOSYS;
}
-static long __vsyscall(3) venosys_1(void)
+#ifdef CONFIG_SYSCTL
+
+#define SYSCALL 0x050f
+#define NOP2 0x9090
+
+/*
+ * NOP out syscall in vsyscall page when not needed.
+ */
+static int vsyscall_sysctl_change(ctl_table *ctl, int write, struct file * filp,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ extern u16 vsysc1, vsysc2;
+ u16 __iomem *map1;
+ u16 __iomem *map2;
+ int ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
+ if (!write)
+ return ret;
+ /* gcc has some trouble with __va(__pa()), so just do it this
+ way. */
+ map1 = ioremap(__pa_symbol(&vsysc1), 2);
+ if (!map1)
+ return -ENOMEM;
+ map2 = ioremap(__pa_symbol(&vsysc2), 2);
+ if (!map2) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ if (!sysctl_vsyscall) {
+ writew(SYSCALL, map1);
+ writew(SYSCALL, map2);
+ } else {
+ writew(NOP2, map1);
+ writew(NOP2, map2);
+ }
+ iounmap(map2);
+out:
+ iounmap(map1);
+ return ret;
+}
+
+static int vsyscall_sysctl_nostrat(ctl_table *t, int __user *name, int nlen,
+ void __user *oldval, size_t __user *oldlenp,
+ void __user *newval, size_t newlen)
{
return -ENOSYS;
+}
+
+static ctl_table kernel_table2[] = {
+ { .ctl_name = 99, .procname = "vsyscall64",
+ .data = &sysctl_vsyscall, .maxlen = sizeof(int), .mode = 0644,
+ .strategy = vsyscall_sysctl_nostrat,
+ .proc_handler = vsyscall_sysctl_change },
+ { 0, }
+};
+
+static ctl_table kernel_root_table2[] = {
+ { .ctl_name = CTL_KERN, .procname = "kernel", .mode = 0555,
+ .child = kernel_table2 },
+ { 0 },
+};
+
+#endif
+#ifndef CONFIG_XEN
+/* Assume __initcall executes before all user space. Hopefully kmod
+ doesn't violate that. We'll find out if it does. */
+static void __cpuinit vsyscall_set_cpu(int cpu)
+{
+ unsigned long *d;
+ unsigned long node = 0;
+#ifdef CONFIG_NUMA
+ node = cpu_to_node[cpu];
+#endif
+ if (cpu_has(&cpu_data[cpu], X86_FEATURE_RDTSCP))
+ write_rdtscp_aux((node << 12) | cpu);
+
+ /* Store cpu number in limit so that it can be loaded quickly
+ in user space in vgetcpu.
+ 12 bits for the CPU and 8 bits for the node. */
+ d = (unsigned long *)(cpu_gdt(cpu) + GDT_ENTRY_PER_CPU);
+ *d = 0x0f40000000000ULL;
+ *d |= cpu;
+ *d |= (node & 0xf) << 12;
+ *d |= (node >> 4) << 48;
+}
+
+static void __cpuinit cpu_vsyscall_init(void *arg)
+{
+ /* preemption should be already off */
+ vsyscall_set_cpu(raw_smp_processor_id());
}
+static int __cpuinit
+cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg)
+{
+ long cpu = (long)arg;
+ if (action == CPU_ONLINE)
+ smp_call_function_single(cpu, cpu_vsyscall_init, NULL, 0, 1);
+ return NOTIFY_DONE;
+}
+#endif
+
static void __init map_vsyscall(void)
{
extern char __vsyscall_0;
unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
+ /* Note that VSYSCALL_MAPPED_PAGES must agree with the code below. */
__set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
}
+#ifdef CONFIG_XEN
+static void __init map_vsyscall_user(void)
+{
+ extern void __set_fixmap_user(enum fixed_addresses, unsigned long, pgprot_t);
+ extern char __vsyscall_0;
+ unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
+
+ __set_fixmap_user(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
+}
+#endif
+
static int __init vsyscall_init(void)
{
- BUG_ON(((unsigned long) &vgettimeofday !=
- VSYSCALL_ADDR(__NR_vgettimeofday)));
+ BUG_ON(((unsigned long) &vgettimeofday !=
+ VSYSCALL_ADDR(__NR_vgettimeofday)));
BUG_ON((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime));
BUG_ON((VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE)));
+ BUG_ON((unsigned long) &vgetcpu != VSYSCALL_ADDR(__NR_vgetcpu));
map_vsyscall();
- sysctl_vsyscall = 1;
-
+#ifdef CONFIG_XEN
+ map_vsyscall_user();
+ sysctl_vsyscall = 0; /* disable vgettimeofay() */
+#endif
+#ifdef CONFIG_SYSCTL
+ register_sysctl_table(kernel_root_table2, 0);
+#endif
+#ifndef CONFIG_XEN
+ on_each_cpu(cpu_vsyscall_init, NULL, 0, 1);
+ hotcpu_notifier(cpu_vsyscall_notifier, 0);
+#endif
return 0;
}
git://git.onelab.eu / linux-2.6.git / blobdiff