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Commit 6fcac6d3 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

xen64: set up syscall and sysenter entrypoints for 64-bit 



We set up entrypoints for syscall and sysenter.  sysenter is only used
for 32-bit compat processes, whereas syscall can be used in by both 32
and 64-bit processes.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.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 d6182fbf

arch/x86/xen/enlighten.c

+4 −0
Original line number Diff line number Diff line
@@ -1139,6 +1139,10 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = { 


	.iret = xen_iret,

	.irq_enable_sysexit = xen_sysexit,

#ifdef CONFIG_X86_64

	.usergs_sysret32 = xen_sysret32,

	.usergs_sysret64 = xen_sysret64,

#endif



	.load_tr_desc = paravirt_nop,

	.set_ldt = xen_set_ldt,

arch/x86/xen/setup.c

+39 −3
Original line number Diff line number Diff line
@@ -86,9 +86,11 @@ static void xen_idle(void) 
 */

static void __init fiddle_vdso(void)

{

#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)

	extern const char vdso32_default_start;

	u32 *mask = VDSO32_SYMBOL(&vdso32_default_start, NOTE_MASK);

	*mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;

#endif

}



static __cpuinit int register_callback(unsigned type, const void *func)
@@ -106,15 +108,48 @@ void __cpuinit xen_enable_sysenter(void) 
{

	int cpu = smp_processor_id();

	extern void xen_sysenter_target(void);

	int ret;



#ifdef CONFIG_X86_32

	if (!boot_cpu_has(X86_FEATURE_SEP)) {

		return;

	}

#else

	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL &&

	    boot_cpu_data.x86_vendor != X86_VENDOR_CENTAUR) {

		return;

	}

#endif



	if (!boot_cpu_has(X86_FEATURE_SEP) ||

	    register_callback(CALLBACKTYPE_sysenter,

			      xen_sysenter_target) != 0) {

	ret = register_callback(CALLBACKTYPE_sysenter, xen_sysenter_target);

	if(ret != 0) {

		clear_cpu_cap(&cpu_data(cpu), X86_FEATURE_SEP);

		clear_cpu_cap(&boot_cpu_data, X86_FEATURE_SEP);

	}

}



void __cpuinit xen_enable_syscall(void)

{

#ifdef CONFIG_X86_64

	int cpu = smp_processor_id();

	int ret;

	extern void xen_syscall_target(void);

	extern void xen_syscall32_target(void);



	ret = register_callback(CALLBACKTYPE_syscall, xen_syscall_target);

	if (ret != 0) {

		printk("failed to set syscall: %d\n", ret);

		clear_cpu_cap(&cpu_data(cpu), X86_FEATURE_SYSCALL);

		clear_cpu_cap(&boot_cpu_data, X86_FEATURE_SYSCALL);

	} else {

		ret = register_callback(CALLBACKTYPE_syscall32,

					xen_syscall32_target);

		if (ret != 0)

			printk("failed to set 32-bit syscall: %d\n", ret);

	}

#endif /* CONFIG_X86_64 */

}



void __init xen_arch_setup(void)

{

	struct physdev_set_iopl set_iopl;
@@ -131,6 +166,7 @@ void __init xen_arch_setup(void) 
		BUG();



	xen_enable_sysenter();

	xen_enable_syscall();



	set_iopl.iopl = 1;

	rc = HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);

arch/x86/xen/smp.c

+1 −0
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ static __cpuinit void cpu_bringup_and_idle(void) 
	preempt_disable();



	xen_enable_sysenter();

	xen_enable_syscall();



	cpu = smp_processor_id();

	smp_store_cpu_info(cpu);

arch/x86/xen/xen-asm_64.S

+127 −2
Original line number Diff line number Diff line
@@ -15,6 +15,8 @@ 


#include <asm/asm-offsets.h>

#include <asm/processor-flags.h>

#include <asm/errno.h>

#include <asm/segment.h>



#include <xen/interface/xen.h>
@@ -138,9 +140,132 @@ ENTRY(xen_adjust_exception_frame) 
	mov 8+8(%rsp),%r11

	ret $16



hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32

/*

	Xen64 iret frame:



	ss

	rsp

	rflags

	cs

	rip		<-- standard iret frame



	flags



	rcx		}

	r11		}<-- pushed by hypercall page

rsp ->	rax		}

 */

ENTRY(xen_iret)

	pushq $0

	jmp hypercall_page + __HYPERVISOR_iret * 32

1:	jmp hypercall_iret

ENDPATCH(xen_iret)

RELOC(xen_iret, 1b+1)



/*

	sysexit is not used for 64-bit processes, so it's

	only ever used to return to 32-bit compat userspace.

 */

ENTRY(xen_sysexit)

	ud2a
 
	pushq $__USER32_DS

	pushq %rcx

	pushq $X86_EFLAGS_IF

	pushq $__USER32_CS

	pushq %rdx



	pushq $VGCF_in_syscall

1:	jmp hypercall_iret

ENDPATCH(xen_sysexit)

RELOC(xen_sysexit, 1b+1)



ENTRY(xen_sysret64)

	/* We're already on the usermode stack at this point, but still

	   with the kernel gs, so we can easily switch back */

	movq %rsp, %gs:pda_oldrsp

	movq %gs:pda_kernelstack,%rsp



	pushq $__USER_DS

	pushq %gs:pda_oldrsp

	pushq %r11

	pushq $__USER_CS

	pushq %rcx



	pushq $VGCF_in_syscall

1:	jmp hypercall_iret

ENDPATCH(xen_sysret64)

RELOC(xen_sysret64, 1b+1)



ENTRY(xen_sysret32)

	/* We're already on the usermode stack at this point, but still

	   with the kernel gs, so we can easily switch back */

	movq %rsp, %gs:pda_oldrsp

	movq %gs:pda_kernelstack, %rsp



	pushq $__USER32_DS

	pushq %gs:pda_oldrsp

	pushq %r11

	pushq $__USER32_CS

	pushq %rcx



	pushq $VGCF_in_syscall

1:	jmp hypercall_iret

ENDPATCH(xen_sysret32)

RELOC(xen_sysret32, 1b+1)



/*

	Xen handles syscall callbacks much like ordinary exceptions,

	which means we have:

	 - kernel gs

	 - kernel rsp

	 - an iret-like stack frame on the stack (including rcx and r11):

		ss

		rsp

		rflags

		cs

		rip

		r11

	rsp->	rcx



	In all the entrypoints, we undo all that to make it look

	like a CPU-generated syscall/sysenter and jump to the normal

	entrypoint.

 */



.macro undo_xen_syscall

	mov 0*8(%rsp),%rcx

	mov 1*8(%rsp),%r11

	mov 5*8(%rsp),%rsp

.endm



/* Normal 64-bit system call target */

ENTRY(xen_syscall_target)

	undo_xen_syscall

	jmp system_call_after_swapgs

ENDPROC(xen_syscall_target)



#ifdef CONFIG_IA32_EMULATION



/* 32-bit compat syscall target */

ENTRY(xen_syscall32_target)

	undo_xen_syscall

	jmp ia32_cstar_target

ENDPROC(xen_syscall32_target)



/* 32-bit compat sysenter target */

ENTRY(xen_sysenter_target)

	undo_xen_syscall

	jmp ia32_sysenter_target

ENDPROC(xen_sysenter_target)



#else /* !CONFIG_IA32_EMULATION */



ENTRY(xen_syscall32_target)

ENTRY(xen_sysenter_target)

	lea 16(%rsp), %rsp	/* strip %rcx,%r11 */

	mov $-ENOSYS, %rax

	pushq $VGCF_in_syscall

	jmp hypercall_iret

ENDPROC(xen_syscall32_target)

ENDPROC(xen_sysenter_target)



#endif	/* CONFIG_IA32_EMULATION */

arch/x86/xen/xen-ops.h

+3 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ char * __init xen_memory_setup(void); 
void __init xen_arch_setup(void);

void __init xen_init_IRQ(void);

void xen_enable_sysenter(void);

void xen_enable_syscall(void);

void xen_vcpu_restore(void);



void __init xen_build_dynamic_phys_to_machine(void);
@@ -70,6 +71,8 @@ DECL_ASM(void, xen_restore_fl_direct, unsigned long); 
/* These are not functions, and cannot be called normally */

void xen_iret(void);

void xen_sysexit(void);

void xen_sysret32(void);

void xen_sysret64(void);

void xen_adjust_exception_frame(void);



#endif /* XEN_OPS_H */