xen: Attempt to patch inline versions of common operations
This patchs adds the mechanism to allow us to patch inline versions of
common operations.
The implementations of the direct-access versions save_fl, restore_fl,
irq_enable and irq_disable are now in assembler, and the same code is
used for both out of line and inline uses.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Keir Fraser <keir@xensource.com>
diff --git a/arch/i386/xen/enlighten.c b/arch/i386/xen/enlighten.c
index e33fa09..4fa62a4 100644
--- a/arch/i386/xen/enlighten.c
+++ b/arch/i386/xen/enlighten.c
@@ -115,6 +115,7 @@
/* This cpu is using the registered vcpu info, even if
later ones fail to. */
per_cpu(xen_vcpu, cpu) = vcpup;
+
printk(KERN_DEBUG "cpu %d using vcpu_info at %p\n",
cpu, vcpup);
}
@@ -177,20 +178,6 @@
return (-flags) & X86_EFLAGS_IF;
}
-static unsigned long xen_save_fl_direct(void)
-{
- unsigned long flags;
-
- /* flag has opposite sense of mask */
- flags = !x86_read_percpu(xen_vcpu_info.evtchn_upcall_mask);
-
- /* convert to IF type flag
- -0 -> 0x00000000
- -1 -> 0xffffffff
- */
- return (-flags) & X86_EFLAGS_IF;
-}
-
static void xen_restore_fl(unsigned long flags)
{
struct vcpu_info *vcpu;
@@ -217,25 +204,6 @@
}
}
-static void xen_restore_fl_direct(unsigned long flags)
-{
- /* convert from IF type flag */
- flags = !(flags & X86_EFLAGS_IF);
-
- /* This is an atomic update, so no need to worry about
- preemption. */
- x86_write_percpu(xen_vcpu_info.evtchn_upcall_mask, flags);
-
- /* If we get preempted here, then any pending event will be
- handled anyway. */
-
- if (flags == 0) {
- barrier(); /* unmask then check (avoid races) */
- if (unlikely(x86_read_percpu(xen_vcpu_info.evtchn_upcall_pending)))
- force_evtchn_callback();
- }
-}
-
static void xen_irq_disable(void)
{
/* There's a one instruction preempt window here. We need to
@@ -246,12 +214,6 @@
preempt_enable_no_resched();
}
-static void xen_irq_disable_direct(void)
-{
- /* Atomic update, so preemption not a concern. */
- x86_write_percpu(xen_vcpu_info.evtchn_upcall_mask, 1);
-}
-
static void xen_irq_enable(void)
{
struct vcpu_info *vcpu;
@@ -272,19 +234,6 @@
force_evtchn_callback();
}
-static void xen_irq_enable_direct(void)
-{
- /* Atomic update, so preemption not a concern. */
- x86_write_percpu(xen_vcpu_info.evtchn_upcall_mask, 0);
-
- /* Doesn't matter if we get preempted here, because any
- pending event will get dealt with anyway. */
-
- barrier(); /* unmask then check (avoid races) */
- if (unlikely(x86_read_percpu(xen_vcpu_info.evtchn_upcall_pending)))
- force_evtchn_callback();
-}
-
static void xen_safe_halt(void)
{
/* Blocking includes an implicit local_irq_enable(). */
@@ -892,6 +841,57 @@
}
}
+static unsigned xen_patch(u8 type, u16 clobbers, void *insns, unsigned len)
+{
+ char *start, *end, *reloc;
+ unsigned ret;
+
+ start = end = reloc = NULL;
+
+#define SITE(x) \
+ case PARAVIRT_PATCH(x): \
+ if (have_vcpu_info_placement) { \
+ start = (char *)xen_##x##_direct; \
+ end = xen_##x##_direct_end; \
+ reloc = xen_##x##_direct_reloc; \
+ } \
+ goto patch_site
+
+ switch (type) {
+ SITE(irq_enable);
+ SITE(irq_disable);
+ SITE(save_fl);
+ SITE(restore_fl);
+#undef SITE
+
+ patch_site:
+ if (start == NULL || (end-start) > len)
+ goto default_patch;
+
+ ret = paravirt_patch_insns(insns, len, start, end);
+
+ /* Note: because reloc is assigned from something that
+ appears to be an array, gcc assumes it's non-null,
+ but doesn't know its relationship with start and
+ end. */
+ if (reloc > start && reloc < end) {
+ int reloc_off = reloc - start;
+ long *relocp = (long *)(insns + reloc_off);
+ long delta = start - (char *)insns;
+
+ *relocp += delta;
+ }
+ break;
+
+ default_patch:
+ default:
+ ret = paravirt_patch_default(type, clobbers, insns, len);
+ break;
+ }
+
+ return ret;
+}
+
static const struct paravirt_ops xen_paravirt_ops __initdata = {
.paravirt_enabled = 1,
.shared_kernel_pmd = 0,
@@ -899,7 +899,7 @@
.name = "Xen",
.banner = xen_banner,
- .patch = paravirt_patch_default,
+ .patch = xen_patch,
.memory_setup = xen_memory_setup,
.arch_setup = xen_arch_setup,
@@ -1076,6 +1076,7 @@
.emergency_restart = xen_emergency_restart,
};
+
/* First C function to be called on Xen boot */
asmlinkage void __init xen_start_kernel(void)
{