7209a75d20
This moves the espfix64 logic into native_iret. To make this work, it gets rid of the native patch for INTERRUPT_RETURN: INTERRUPT_RETURN on native kernels is now 'jmp native_iret'. This changes the 16-bit SS behavior on Xen from OOPSing to leaking some bits of the Xen hypervisor's RSP (I think). [ hpa: this is a nonzero cost on native, but probably not enough to measure. Xen needs to fix this in their own code, probably doing something equivalent to espfix64. ] Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/7b8f1d8ef6597cb16ae004a43c56980a7de3cf94.1406129132.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: <stable@vger.kernel.org>
209 lines
4 KiB
C
209 lines
4 KiB
C
#ifndef _X86_IRQFLAGS_H_
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#define _X86_IRQFLAGS_H_
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#include <asm/processor-flags.h>
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#ifndef __ASSEMBLY__
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/*
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* Interrupt control:
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*/
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static inline unsigned long native_save_fl(void)
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{
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unsigned long flags;
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/*
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* "=rm" is safe here, because "pop" adjusts the stack before
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* it evaluates its effective address -- this is part of the
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* documented behavior of the "pop" instruction.
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*/
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asm volatile("# __raw_save_flags\n\t"
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"pushf ; pop %0"
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: "=rm" (flags)
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: /* no input */
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: "memory");
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return flags;
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}
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static inline void native_restore_fl(unsigned long flags)
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{
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asm volatile("push %0 ; popf"
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: /* no output */
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:"g" (flags)
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:"memory", "cc");
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}
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static inline void native_irq_disable(void)
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{
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asm volatile("cli": : :"memory");
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}
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static inline void native_irq_enable(void)
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{
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asm volatile("sti": : :"memory");
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}
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static inline void native_safe_halt(void)
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{
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asm volatile("sti; hlt": : :"memory");
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}
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static inline void native_halt(void)
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{
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asm volatile("hlt": : :"memory");
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}
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#endif
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#ifdef CONFIG_PARAVIRT
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#include <asm/paravirt.h>
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#else
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#ifndef __ASSEMBLY__
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#include <linux/types.h>
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static inline notrace unsigned long arch_local_save_flags(void)
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{
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return native_save_fl();
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}
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static inline notrace void arch_local_irq_restore(unsigned long flags)
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{
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native_restore_fl(flags);
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}
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static inline notrace void arch_local_irq_disable(void)
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{
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native_irq_disable();
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}
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static inline notrace void arch_local_irq_enable(void)
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{
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native_irq_enable();
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}
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/*
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* Used in the idle loop; sti takes one instruction cycle
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* to complete:
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*/
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static inline void arch_safe_halt(void)
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{
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native_safe_halt();
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}
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/*
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* Used when interrupts are already enabled or to
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* shutdown the processor:
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*/
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static inline void halt(void)
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{
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native_halt();
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}
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/*
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* For spinlocks, etc:
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*/
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static inline notrace unsigned long arch_local_irq_save(void)
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{
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unsigned long flags = arch_local_save_flags();
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arch_local_irq_disable();
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return flags;
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}
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#else
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#define ENABLE_INTERRUPTS(x) sti
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#define DISABLE_INTERRUPTS(x) cli
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#ifdef CONFIG_X86_64
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#define SWAPGS swapgs
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/*
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* Currently paravirt can't handle swapgs nicely when we
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* don't have a stack we can rely on (such as a user space
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* stack). So we either find a way around these or just fault
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* and emulate if a guest tries to call swapgs directly.
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*
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* Either way, this is a good way to document that we don't
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* have a reliable stack. x86_64 only.
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*/
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#define SWAPGS_UNSAFE_STACK swapgs
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#define PARAVIRT_ADJUST_EXCEPTION_FRAME /* */
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#define INTERRUPT_RETURN jmp native_iret
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#define USERGS_SYSRET64 \
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swapgs; \
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sysretq;
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#define USERGS_SYSRET32 \
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swapgs; \
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sysretl
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#define ENABLE_INTERRUPTS_SYSEXIT32 \
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swapgs; \
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sti; \
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sysexit
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#else
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#define INTERRUPT_RETURN iret
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#define ENABLE_INTERRUPTS_SYSEXIT sti; sysexit
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#define GET_CR0_INTO_EAX movl %cr0, %eax
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#endif
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#endif /* __ASSEMBLY__ */
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#endif /* CONFIG_PARAVIRT */
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#ifndef __ASSEMBLY__
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static inline int arch_irqs_disabled_flags(unsigned long flags)
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{
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return !(flags & X86_EFLAGS_IF);
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}
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static inline int arch_irqs_disabled(void)
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{
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unsigned long flags = arch_local_save_flags();
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return arch_irqs_disabled_flags(flags);
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}
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#else
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#ifdef CONFIG_X86_64
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#define ARCH_LOCKDEP_SYS_EXIT call lockdep_sys_exit_thunk
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#define ARCH_LOCKDEP_SYS_EXIT_IRQ \
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TRACE_IRQS_ON; \
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sti; \
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SAVE_REST; \
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LOCKDEP_SYS_EXIT; \
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RESTORE_REST; \
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cli; \
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TRACE_IRQS_OFF;
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#else
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#define ARCH_LOCKDEP_SYS_EXIT \
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pushl %eax; \
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pushl %ecx; \
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pushl %edx; \
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call lockdep_sys_exit; \
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popl %edx; \
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popl %ecx; \
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popl %eax;
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#define ARCH_LOCKDEP_SYS_EXIT_IRQ
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#endif
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#ifdef CONFIG_TRACE_IRQFLAGS
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# define TRACE_IRQS_ON call trace_hardirqs_on_thunk;
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# define TRACE_IRQS_OFF call trace_hardirqs_off_thunk;
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#else
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# define TRACE_IRQS_ON
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# define TRACE_IRQS_OFF
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#endif
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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# define LOCKDEP_SYS_EXIT ARCH_LOCKDEP_SYS_EXIT
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# define LOCKDEP_SYS_EXIT_IRQ ARCH_LOCKDEP_SYS_EXIT_IRQ
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# else
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# define LOCKDEP_SYS_EXIT
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# define LOCKDEP_SYS_EXIT_IRQ
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# endif
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#endif /* __ASSEMBLY__ */
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#endif
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