diff options
Diffstat (limited to 'arch/um/sys-x86_64/syscalls.c')
| -rw-r--r-- | arch/um/sys-x86_64/syscalls.c | 73 |
1 files changed, 55 insertions, 18 deletions
diff --git a/arch/um/sys-x86_64/syscalls.c b/arch/um/sys-x86_64/syscalls.c index 73ce4463f70..f309fa9bc23 100644 --- a/arch/um/sys-x86_64/syscalls.c +++ b/arch/um/sys-x86_64/syscalls.c @@ -16,6 +16,7 @@ #include "asm/prctl.h" /* XXX This should get the constants from libc */ #include "choose-mode.h" #include "kern.h" +#include "os.h" asmlinkage long sys_uname64(struct new_utsname __user * name) { @@ -58,40 +59,67 @@ static long arch_prctl_tt(int code, unsigned long addr) #ifdef CONFIG_MODE_SKAS -/* XXX: Must also call arch_prctl in the host, beside saving the segment bases! */ -static long arch_prctl_skas(int code, unsigned long addr) +static long arch_prctl_skas(int code, unsigned long __user *addr) { - long ret = 0; + unsigned long *ptr = addr, tmp; + long ret; + int pid = current->mm->context.skas.id.u.pid; + /* + * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to + * be safe), we need to call arch_prctl on the host because + * setting %fs may result in something else happening (like a + * GDT being set instead). So, we let the host fiddle the + * registers and restore them afterwards. + * + * So, the saved registers are stored to the process (this + * needed because a stub may have been the last thing to run), + * arch_prctl is run on the host, then the registers are read + * back. + */ switch(code){ case ARCH_SET_FS: - current->thread.regs.regs.skas.regs[FS_BASE / sizeof(unsigned long)] = addr; - break; case ARCH_SET_GS: - current->thread.regs.regs.skas.regs[GS_BASE / sizeof(unsigned long)] = addr; + restore_registers(pid, ¤t->thread.regs.regs); + break; + case ARCH_GET_FS: + case ARCH_GET_GS: + /* + * With these two, we read to a local pointer and + * put_user it to the userspace pointer that we were + * given. If addr isn't valid (because it hasn't been + * faulted in or is just bogus), we want put_user to + * fault it in (or return -EFAULT) instead of having + * the host return -EFAULT. + */ + ptr = &tmp; + } + + ret = os_arch_prctl(pid, code, ptr); + if(ret) + return ret; + + switch(code){ + case ARCH_SET_FS: + case ARCH_SET_GS: + save_registers(pid, ¤t->thread.regs.regs); break; case ARCH_GET_FS: - ret = put_user(current->thread.regs.regs.skas. - regs[FS_BASE / sizeof(unsigned long)], - (unsigned long __user *)addr); + ret = put_user(tmp, addr); break; case ARCH_GET_GS: - ret = put_user(current->thread.regs.regs.skas. - regs[GS_BASE / sizeof(unsigned long)], - (unsigned long __user *)addr); + ret = put_user(tmp, addr); break; - default: - ret = -EINVAL; - break; } - return(ret); + return ret; } #endif long sys_arch_prctl(int code, unsigned long addr) { - return(CHOOSE_MODE_PROC(arch_prctl_tt, arch_prctl_skas, code, addr)); + return CHOOSE_MODE_PROC(arch_prctl_tt, arch_prctl_skas, code, + (unsigned long __user *) addr); } long sys_clone(unsigned long clone_flags, unsigned long newsp, @@ -105,5 +133,14 @@ long sys_clone(unsigned long clone_flags, unsigned long newsp, ret = do_fork(clone_flags, newsp, ¤t->thread.regs, 0, parent_tid, child_tid); current->thread.forking = 0; - return(ret); + return ret; +} + +void arch_switch_to_skas(struct task_struct *from, struct task_struct *to) +{ + if(to->thread.arch.fs == 0) + return; + + arch_prctl_skas(ARCH_SET_FS, (void __user *) to->thread.arch.fs); } + |