X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fx86_64%2Fkernel%2Fvsyscall.c;h=2e5734425949648ea92bd8d7fd9e65e6f99a8ed5;hb=f7f1b0f1e2fbadeab12d24236000e778aa9b1ead;hp=f28a07c77b48562e90573858a28c9eb52c4f2d9f;hpb=6a77f38946aaee1cd85eeec6cf4229b204c15071;p=linux-2.6.git diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c index f28a07c77..2e5734425 100644 --- a/arch/x86_64/kernel/vsyscall.c +++ b/arch/x86_64/kernel/vsyscall.c @@ -9,30 +9,14 @@ * 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 @@ -41,6 +25,7 @@ #include #include #include +#include #include #include @@ -62,8 +47,7 @@ static force_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; } @@ -81,13 +65,14 @@ static force_inline void do_vgettimeofday(struct timeval * tv) usec = (__xtime.tv_nsec / 1000) + (__jiffies - __wall_jiffies) * (1000000 / HZ); - if (__vxtime.mode == VXTIME_TSC) { + if (__vxtime.mode != VXTIME_HPET) { sync_core(); rdtscll(t); - if (t < __vxtime.last_tsc) t = __vxtime.last_tsc; + 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) - __vxtime.last) * __vxtime.quot) >> 32; @@ -101,14 +86,13 @@ static force_inline void do_vgettimeofday(struct timeval * tv) /* 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) { - *tz = __sys_tz; + *tz = __sys_tz; } - static force_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; @@ -117,7 +101,7 @@ static force_inline int gettimeofday(struct timeval *tv, struct timezone *tz) static force_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; @@ -126,7 +110,7 @@ static force_inline long time_syscall(long *t) static int __vsyscall(0) vgettimeofday(struct timeval * tv, struct timezone * tz) { if (unlikely(!__sysctl_vsyscall)) - return gettimeofday(tv,tz); + return gettimeofday(tv,tz); if (tv) do_vgettimeofday(tv); if (tz) @@ -153,9 +137,71 @@ static long __vsyscall(2) venosys_0(void) static long __vsyscall(3) venosys_1(void) { return -ENOSYS; +} + +#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 *map1, *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) { + *map1 = SYSCALL; + *map2 = SYSCALL; + } else { + *map1 = NOP2; + *map2 = NOP2; + } + 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, + void **context) +{ + 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 + static void __init map_vsyscall(void) { extern char __vsyscall_0; @@ -166,13 +212,14 @@ static void __init map_vsyscall(void) 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))); map_vsyscall(); - sysctl_vsyscall = 1; - +#ifdef CONFIG_SYSCTL + register_sysctl_table(kernel_root_table2, 0); +#endif return 0; }