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Commit e17f8234 authored by Boris Ostrovsky's avatar Boris Ostrovsky Committed by Ingo Molnar
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x86/entry/64/paravirt: Use paravirt-safe macro to access eflags 



Commit 1d3e53e8 ("x86/entry/64: Refactor IRQ stacks and make them
NMI-safe") added DEBUG_ENTRY_ASSERT_IRQS_OFF macro that acceses eflags
using 'pushfq' instruction when testing for IF bit. On PV Xen guests
looking at IF flag directly will always see it set, resulting in 'ud2'.

Introduce SAVE_FLAGS() macro that will use appropriate save_fl pv op when
running paravirt.

Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20171204150604.899457242@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 2aeb0736

arch/x86/entry/entry_64.S

+4 −3
Original line number Diff line number Diff line
@@ -462,12 +462,13 @@ END(irq_entries_start) 


.macro DEBUG_ENTRY_ASSERT_IRQS_OFF

#ifdef CONFIG_DEBUG_ENTRY

	pushfq

	testl $X86_EFLAGS_IF, (%rsp)

	pushq %rax

	SAVE_FLAGS(CLBR_RAX)

	testl $X86_EFLAGS_IF, %eax

	jz .Lokay_\@

	ud2

.Lokay_\@:

	addq $8, %rsp

	popq %rax

#endif

.endm

arch/x86/include/asm/irqflags.h

+3 −0
Original line number Diff line number Diff line
@@ -142,6 +142,9 @@ static inline notrace unsigned long arch_local_irq_save(void) 
	swapgs;					\

	sysretl



#ifdef CONFIG_DEBUG_ENTRY

#define SAVE_FLAGS(x)		pushfq; popq %rax

#endif

#else

#define INTERRUPT_RETURN		iret

#define ENABLE_INTERRUPTS_SYSEXIT	sti; sysexit

arch/x86/include/asm/paravirt.h

+9 −0
Original line number Diff line number Diff line
@@ -927,6 +927,15 @@ extern void default_banner(void); 
	PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usergs_sysret64),	\

		  CLBR_NONE,						\

		  jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_usergs_sysret64))



#ifdef CONFIG_DEBUG_ENTRY

#define SAVE_FLAGS(clobbers)                                        \

	PARA_SITE(PARA_PATCH(pv_irq_ops, PV_IRQ_save_fl), clobbers, \

		  PV_SAVE_REGS(clobbers | CLBR_CALLEE_SAVE);        \

		  call PARA_INDIRECT(pv_irq_ops+PV_IRQ_save_fl);    \

		  PV_RESTORE_REGS(clobbers | CLBR_CALLEE_SAVE);)

#endif



#endif	/* CONFIG_X86_32 */



#endif /* __ASSEMBLY__ */

arch/x86/kernel/asm-offsets_64.c

+3 −0
Original line number Diff line number Diff line
@@ -23,6 +23,9 @@ int main(void) 
#ifdef CONFIG_PARAVIRT

	OFFSET(PV_CPU_usergs_sysret64, pv_cpu_ops, usergs_sysret64);

	OFFSET(PV_CPU_swapgs, pv_cpu_ops, swapgs);

#ifdef CONFIG_DEBUG_ENTRY

	OFFSET(PV_IRQ_save_fl, pv_irq_ops, save_fl);

#endif

	BLANK();

#endif