From d4ce0f26c790af8e829d3fad0a6787f40f98e24f Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Wed, 29 Jul 2015 01:41:17 -0400 Subject: [PATCH] x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86' Move the non-regs fields to the off-stack data. Signed-off-by: Brian Gerst Acked-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1438148483-11932-3-git-send-email-brgerst@gmail.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/vm86.h | 16 +++++++------- arch/x86/kernel/vm86_32.c | 42 +++++++++++++++++++------------------ 2 files changed, 30 insertions(+), 28 deletions(-) diff --git a/arch/x86/include/asm/vm86.h b/arch/x86/include/asm/vm86.h index 20b43b7a950b..47c7648338ee 100644 --- a/arch/x86/include/asm/vm86.h +++ b/arch/x86/include/asm/vm86.h @@ -37,13 +37,7 @@ struct kernel_vm86_struct { * Therefore, pt_regs in fact points to a complete 'kernel_vm86_struct' * in kernelspace, hence we need not reget the data from userspace. */ -#define VM86_TSS_ESP0 flags - unsigned long flags; - unsigned long screen_bitmap; - unsigned long cpu_type; - struct revectored_struct int_revectored; - struct revectored_struct int21_revectored; - struct vm86plus_info_struct vm86plus; +#define VM86_TSS_ESP0 regs32 struct pt_regs *regs32; /* here we save the pointer to the old regs */ /* * The below is not part of the structure, but the stack layout continues @@ -59,10 +53,16 @@ struct kernel_vm86_struct { struct vm86 { struct vm86plus_struct __user *vm86_info; - unsigned long screen_bitmap; unsigned long v86flags; unsigned long v86mask; unsigned long saved_sp0; + + unsigned long flags; + unsigned long screen_bitmap; + unsigned long cpu_type; + struct revectored_struct int_revectored; + struct revectored_struct int21_revectored; + struct vm86plus_info_struct vm86plus; }; #ifdef CONFIG_VM86 diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c index bfa59b1400b9..f71b4b9452f1 100644 --- a/arch/x86/kernel/vm86_32.c +++ b/arch/x86/kernel/vm86_32.c @@ -68,7 +68,6 @@ #define KVM86 ((struct kernel_vm86_struct *)regs) -#define VMPI KVM86->vm86plus /* @@ -114,7 +113,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs) set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->v86mask); user = vm86->vm86_info; - if (!access_ok(VERIFY_WRITE, user, VMPI.is_vm86pus ? + if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.is_vm86pus ? sizeof(struct vm86plus_struct) : sizeof(struct vm86_struct))) { pr_alert("could not access userspace vm86_info\n"); @@ -282,25 +281,27 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus, get_user_ex(info->regs.fs, &v86->regs.fs); get_user_ex(info->regs.gs, &v86->regs.gs); - get_user_ex(info->flags, &v86->flags); - get_user_ex(info->screen_bitmap, &v86->screen_bitmap); - get_user_ex(info->cpu_type, &v86->cpu_type); + get_user_ex(vm86->flags, &v86->flags); + get_user_ex(vm86->screen_bitmap, &v86->screen_bitmap); + get_user_ex(vm86->cpu_type, &v86->cpu_type); } get_user_catch(err); if (err) return err; - if (copy_from_user(&info->int_revectored, &v86->int_revectored, + if (copy_from_user(&vm86->int_revectored, &v86->int_revectored, sizeof(struct revectored_struct))) return -EFAULT; - if (copy_from_user(&info->int21_revectored, &v86->int21_revectored, + if (copy_from_user(&vm86->int21_revectored, &v86->int21_revectored, sizeof(struct revectored_struct))) return -EFAULT; if (plus) { - if (copy_from_user(&info->vm86plus, &v86->vm86plus, + if (copy_from_user(&vm86->vm86plus, &v86->vm86plus, sizeof(struct vm86plus_info_struct))) return -EFAULT; - info->vm86plus.is_vm86pus = 1; - } + vm86->vm86plus.is_vm86pus = 1; + } else + memset(&vm86->vm86plus, 0, + sizeof(struct vm86plus_info_struct)); info->regs32 = current_pt_regs(); vm86->vm86_info = v86; @@ -317,7 +318,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus, info->regs.pt.orig_ax = info->regs32->orig_ax; - switch (info->cpu_type) { + switch (vm86->cpu_type) { case CPU_286: vm86->v86mask = 0; break; @@ -346,8 +347,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus, load_sp0(tss, &tsk->thread); put_cpu(); - vm86->screen_bitmap = info->screen_bitmap; - if (info->flags & VM86_SCREEN_BITMAP) + if (vm86->flags & VM86_SCREEN_BITMAP) mark_screen_rdonly(tsk->mm); /*call __audit_syscall_exit since we do not exit via the normal paths */ @@ -539,12 +539,13 @@ static void do_int(struct kernel_vm86_regs *regs, int i, { unsigned long __user *intr_ptr; unsigned long segoffs; + struct kernel_vm86_info *vm86 = current->thread.vm86; if (regs->pt.cs == BIOSSEG) goto cannot_handle; - if (is_revectored(i, &KVM86->int_revectored)) + if (is_revectored(i, &vm86->int_revectored)) goto cannot_handle; - if (i == 0x21 && is_revectored(AH(regs), &KVM86->int21_revectored)) + if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) goto cannot_handle; intr_ptr = (unsigned long __user *) (i << 2); if (get_user(segoffs, intr_ptr)) @@ -568,7 +569,7 @@ static void do_int(struct kernel_vm86_regs *regs, int i, int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno) { - if (VMPI.is_vm86pus) { + if (current->thread.vm86->vm86plus.is_vm86pus) { if ((trapno == 3) || (trapno == 1)) { KVM86->regs32->ax = VM86_TRAP + (trapno << 8); /* setting this flag forces the code in entry_32.S to @@ -595,12 +596,13 @@ void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) unsigned char __user *ssp; unsigned short ip, sp, orig_flags; int data32, pref_done; + struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus; #define CHECK_IF_IN_TRAP \ - if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \ + if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \ newflags |= X86_EFLAGS_TF #define VM86_FAULT_RETURN do { \ - if (VMPI.force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \ + if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \ return_to_32bit(regs, VM86_PICRETURN); \ if (orig_flags & X86_EFLAGS_TF) \ handle_vm86_trap(regs, 0, 1); \ @@ -670,8 +672,8 @@ void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code) case 0xcd: { int intno = popb(csp, ip, simulate_sigsegv); IP(regs) = ip; - if (VMPI.vm86dbg_active) { - if ((1 << (intno & 7)) & VMPI.vm86dbg_intxxtab[intno >> 3]) + if (vmpi->vm86dbg_active) { + if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3]) return_to_32bit(regs, VM86_INTx + (intno << 8)); } do_int(regs, intno, ssp, sp);