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x86/vm86: Eliminate 'struct kernel_vm86_struct'

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Now there is no vm86-specific data left on the kernel stack
while in userspace, except for the 32-bit regs.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438148483-11932-4-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Brian Gerst
2015-07-29 01:41:18 -04:00
committed by Ingo Molnar
parent d4ce0f26c7
commit 90c6085a24
2 changed files with 42 additions and 78 deletions
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25
arch/x86/include/asm/vm86.h
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@@ -27,32 +27,9 @@ struct kernel_vm86_regs {
unsigned short gs, __gsh;
};
struct kernel_vm86_struct {
struct kernel_vm86_regs regs;
/*
* the below part remains on the kernel stack while we are in VM86 mode.
* 'tss.esp0' then contains the address of VM86_TSS_ESP0 below, and when we
* get forced back from VM86, the CPU and "SAVE_ALL" will restore the above
* 'struct kernel_vm86_regs' with the then actual values.
* 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 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
* this way. In front of 'return-eip' may be some data, depending on
* compilation, so we don't rely on this and save the pointer to 'oldregs'
* in 'regs32' above.
* However, with GCC-2.7.2 and the current CFLAGS you see exactly this:
long return-eip; from call to vm86()
struct pt_regs oldregs; user space registers as saved by syscall
*/
};
struct vm86 {
struct vm86plus_struct __user *vm86_info;
struct pt_regs *regs32;
unsigned long v86flags;
unsigned long v86mask;
unsigned long saved_sp0;