1/* 2 * Asm versions of Xen pv-ops, suitable for either direct use or 3 * inlining. The inline versions are the same as the direct-use 4 * versions, with the pre- and post-amble chopped off. 5 * 6 * This code is encoded for size rather than absolute efficiency, with 7 * a view to being able to inline as much as possible. 8 * 9 * We only bother with direct forms (ie, vcpu in percpu data) of the 10 * operations here; the indirect forms are better handled in C, since 11 * they're generally too large to inline anyway. 12 */ 13 14#include <asm/asm-offsets.h> 15#include <asm/percpu.h> 16#include <asm/processor-flags.h> 17 18#include "xen-asm.h" 19 20/* 21 * Enable events. This clears the event mask and tests the pending 22 * event status with one and operation. If there are pending events, 23 * then enter the hypervisor to get them handled. 24 */ 25ENTRY(xen_irq_enable_direct) 26 /* Unmask events */ 27 movb $0, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask 28 29 /* 30 * Preempt here doesn't matter because that will deal with any 31 * pending interrupts. The pending check may end up being run 32 * on the wrong CPU, but that doesn't hurt. 33 */ 34 35 /* Test for pending */ 36 testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending 37 jz 1f 38 392: call check_events 401: 41ENDPATCH(xen_irq_enable_direct) 42 ret 43 ENDPROC(xen_irq_enable_direct) 44 RELOC(xen_irq_enable_direct, 2b+1) 45 46 47/* 48 * Disabling events is simply a matter of making the event mask 49 * non-zero. 50 */ 51ENTRY(xen_irq_disable_direct) 52 movb $1, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask 53ENDPATCH(xen_irq_disable_direct) 54 ret 55 ENDPROC(xen_irq_disable_direct) 56 RELOC(xen_irq_disable_direct, 0) 57 58/* 59 * (xen_)save_fl is used to get the current interrupt enable status. 60 * Callers expect the status to be in X86_EFLAGS_IF, and other bits 61 * may be set in the return value. We take advantage of this by 62 * making sure that X86_EFLAGS_IF has the right value (and other bits 63 * in that byte are 0), but other bits in the return value are 64 * undefined. We need to toggle the state of the bit, because Xen and 65 * x86 use opposite senses (mask vs enable). 66 */ 67ENTRY(xen_save_fl_direct) 68 testb $0xff, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask 69 setz %ah 70 addb %ah, %ah 71ENDPATCH(xen_save_fl_direct) 72 ret 73 ENDPROC(xen_save_fl_direct) 74 RELOC(xen_save_fl_direct, 0) 75 76 77/* 78 * In principle the caller should be passing us a value return from 79 * xen_save_fl_direct, but for robustness sake we test only the 80 * X86_EFLAGS_IF flag rather than the whole byte. After setting the 81 * interrupt mask state, it checks for unmasked pending events and 82 * enters the hypervisor to get them delivered if so. 83 */ 84ENTRY(xen_restore_fl_direct) 85#ifdef CONFIG_X86_64 86 testw $X86_EFLAGS_IF, %di 87#else 88 testb $X86_EFLAGS_IF>>8, %ah 89#endif 90 setz PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_mask 91 /* 92 * Preempt here doesn't matter because that will deal with any 93 * pending interrupts. The pending check may end up being run 94 * on the wrong CPU, but that doesn't hurt. 95 */ 96 97 /* check for unmasked and pending */ 98 cmpw $0x0001, PER_CPU_VAR(xen_vcpu_info) + XEN_vcpu_info_pending 99 jnz 1f 1002: call check_events 1011: 102ENDPATCH(xen_restore_fl_direct) 103 ret 104 ENDPROC(xen_restore_fl_direct) 105 RELOC(xen_restore_fl_direct, 2b+1) 106 107 108/* 109 * Force an event check by making a hypercall, but preserve regs 110 * before making the call. 111 */ 112check_events: 113#ifdef CONFIG_X86_32 114 push %eax 115 push %ecx 116 push %edx 117 call xen_force_evtchn_callback 118 pop %edx 119 pop %ecx 120 pop %eax 121#else 122 push %rax 123 push %rcx 124 push %rdx 125 push %rsi 126 push %rdi 127 push %r8 128 push %r9 129 push %r10 130 push %r11 131 call xen_force_evtchn_callback 132 pop %r11 133 pop %r10 134 pop %r9 135 pop %r8 136 pop %rdi 137 pop %rsi 138 pop %rdx 139 pop %rcx 140 pop %rax 141#endif 142 ret 143