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Commit 2be29982 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

x86/paravirt: add sysret/sysexit pvops for returning to 32-bit compatibility userspace 



In a 64-bit system, we need separate sysret/sysexit operations to
return to a 32-bit userspace.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citirx.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c7245da6

arch/x86/ia32/ia32entry.S

+15 −6
Original line number Diff line number Diff line
@@ -61,6 +61,19 @@ 
	CFI_UNDEFINED	r15

	.endm



#ifdef CONFIG_PARAVIRT

ENTRY(native_usergs_sysret32)

	swapgs

	sysretl

ENDPROC(native_usergs_sysret32)



ENTRY(native_irq_enable_sysexit)

	swapgs

	sti

	sysexit

ENDPROC(native_irq_enable_sysexit)

#endif



/*

 * 32bit SYSENTER instruction entry.

 *
@@ -151,10 +164,7 @@ sysenter_do_call: 
	CFI_ADJUST_CFA_OFFSET -8

	CFI_REGISTER rsp,rcx

	TRACE_IRQS_ON

	swapgs

	sti		/* sti only takes effect after the next instruction */

	/* sysexit */

	.byte	0xf, 0x35

	ENABLE_INTERRUPTS_SYSEXIT32



sysenter_tracesys:

	CFI_RESTORE_STATE
@@ -254,8 +264,7 @@ cstar_do_call: 
	TRACE_IRQS_ON

	movl RSP-ARGOFFSET(%rsp),%esp

	CFI_RESTORE rsp

	swapgs

	sysretl

	USERGS_SYSRET32

	

cstar_tracesys:	

	CFI_RESTORE_STATE

arch/x86/kernel/asm-offsets_64.c

+3 −1
Original line number Diff line number Diff line
@@ -62,7 +62,9 @@ int main(void) 
	OFFSET(PV_IRQ_irq_disable, pv_irq_ops, irq_disable);

	OFFSET(PV_IRQ_irq_enable, pv_irq_ops, irq_enable);

	OFFSET(PV_CPU_iret, pv_cpu_ops, iret);

	OFFSET(PV_CPU_usergs_sysret, pv_cpu_ops, usergs_sysret);

	OFFSET(PV_CPU_usergs_sysret32, pv_cpu_ops, usergs_sysret32);

	OFFSET(PV_CPU_usergs_sysret64, pv_cpu_ops, usergs_sysret64);

	OFFSET(PV_CPU_irq_enable_sysexit, pv_cpu_ops, irq_enable_sysexit);

	OFFSET(PV_CPU_swapgs, pv_cpu_ops, swapgs);

	OFFSET(PV_MMU_read_cr2, pv_mmu_ops, read_cr2);

#endif

arch/x86/kernel/entry_64.S

+2 −2
Original line number Diff line number Diff line
@@ -59,7 +59,7 @@ 
#endif	



#ifdef CONFIG_PARAVIRT

ENTRY(native_usergs_sysret)

ENTRY(native_usergs_sysret64)

	swapgs

	sysretq

#endif /* CONFIG_PARAVIRT */
@@ -275,7 +275,7 @@ sysret_check: 
	RESTORE_ARGS 0,-ARG_SKIP,1

	/*CFI_REGISTER	rflags,r11*/

	movq	%gs:pda_oldrsp, %rsp

	USERGS_SYSRET

	USERGS_SYSRET64



	CFI_RESTORE_STATE

	/* Handle reschedules */

arch/x86/kernel/paravirt.c

+7 −5
Original line number Diff line number Diff line
@@ -141,7 +141,8 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf, 
		ret = paravirt_patch_nop();

	else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||

		 type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) ||

		 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret))

		 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret32) ||

		 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))

		/* If operation requires a jmp, then jmp */

		ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);

	else
@@ -193,7 +194,8 @@ static void native_flush_tlb_single(unsigned long addr) 
/* These are in entry.S */

extern void native_iret(void);

extern void native_irq_enable_sysexit(void);

extern void native_usergs_sysret(void);

extern void native_usergs_sysret32(void);

extern void native_usergs_sysret64(void);



static int __init print_banner(void)

{
@@ -329,10 +331,10 @@ struct pv_cpu_ops pv_cpu_ops = { 
	.write_idt_entry = native_write_idt_entry,

	.load_sp0 = native_load_sp0,



#ifdef CONFIG_X86_32

	.irq_enable_sysexit = native_irq_enable_sysexit,

#else

	.usergs_sysret = native_usergs_sysret,

#ifdef CONFIG_X86_64

	.usergs_sysret32 = native_usergs_sysret32,

	.usergs_sysret64 = native_usergs_sysret64,

#endif

	.iret = native_iret,

	.swapgs = native_swapgs,

arch/x86/kernel/paravirt_patch_64.c

+6 −3
Original line number Diff line number Diff line
@@ -14,8 +14,9 @@ DEF_NATIVE(pv_mmu_ops, flush_tlb_single, "invlpg (%rdi)"); 
DEF_NATIVE(pv_cpu_ops, clts, "clts");

DEF_NATIVE(pv_cpu_ops, wbinvd, "wbinvd");



/* the three commands give us more control to how to return from a syscall */

DEF_NATIVE(pv_cpu_ops, usergs_sysret, "swapgs; sysretq;");

DEF_NATIVE(pv_cpu_ops, irq_enable_sysexit, "swapgs; sti; sysexit");

DEF_NATIVE(pv_cpu_ops, usergs_sysret64, "swapgs; sysretq");

DEF_NATIVE(pv_cpu_ops, usergs_sysret32, "swapgs; sysretl");

DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs");



unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
@@ -35,7 +36,9 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf, 
		PATCH_SITE(pv_irq_ops, irq_enable);

		PATCH_SITE(pv_irq_ops, irq_disable);

		PATCH_SITE(pv_cpu_ops, iret);

		PATCH_SITE(pv_cpu_ops, usergs_sysret);

		PATCH_SITE(pv_cpu_ops, irq_enable_sysexit);

		PATCH_SITE(pv_cpu_ops, usergs_sysret32);

		PATCH_SITE(pv_cpu_ops, usergs_sysret64);

		PATCH_SITE(pv_cpu_ops, swapgs);

		PATCH_SITE(pv_mmu_ops, read_cr2);

		PATCH_SITE(pv_mmu_ops, read_cr3);