[PATCH] i386: PARAVIRT: Use patch site IDs computed from offset in paravirt_ops structure

Use patch type identifiers derived from the offset of the operation in
the paravirt_ops structure.  This avoids having to maintain a separate
enum for patch site types.

Also, since the identifier is derived from the offset into
paravirt_ops, the offset can be derived from the identifier.  This is
used to remove replicated information in the various callsite macros,
which has been a source of bugs in the past.

This patch also drops the fused save_fl+cli operation, which doesn't
really add much and makes things more complex - specifically because
it breaks the 1:1 relationship between identifiers and offsets.  If
this operation turns out to be particularly beneficial, then the right
answer is to define a new entrypoint for it.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>

2 files changed, 12 insertions, 41 deletions

diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c
index 54cc14d99740..f2982832d3b9 100644
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -58,7 +58,6 @@ DEF_NATIVE(cli, "cli");
 DEF_NATIVE(sti, "sti");
 DEF_NATIVE(popf, "push %eax; popf");
 DEF_NATIVE(pushf, "pushf; pop %eax");
-DEF_NATIVE(pushf_cli, "pushf; pop %eax; cli");
 DEF_NATIVE(iret, "iret");
 DEF_NATIVE(sti_sysexit, "sti; sysexit");
 
@@ -66,13 +65,12 @@ static const struct native_insns
 {
         const char *start, *end;
 } native_insns[] = {
-        [PARAVIRT_IRQ_DISABLE] = { start_cli, end_cli },
-        [PARAVIRT_IRQ_ENABLE] = { start_sti, end_sti },
-        [PARAVIRT_RESTORE_FLAGS] = { start_popf, end_popf },
-        [PARAVIRT_SAVE_FLAGS] = { start_pushf, end_pushf },
-        [PARAVIRT_SAVE_FLAGS_IRQ_DISABLE] = { start_pushf_cli, end_pushf_cli },
-        [PARAVIRT_INTERRUPT_RETURN] = { start_iret, end_iret },
-        [PARAVIRT_STI_SYSEXIT] = { start_sti_sysexit, end_sti_sysexit },
+        [PARAVIRT_PATCH(irq_disable)] = { start_cli, end_cli },
+        [PARAVIRT_PATCH(irq_enable)] = { start_sti, end_sti },
+        [PARAVIRT_PATCH(restore_fl)] = { start_popf, end_popf },
+        [PARAVIRT_PATCH(save_fl)] = { start_pushf, end_pushf },
+        [PARAVIRT_PATCH(iret)] = { start_iret, end_iret },
+        [PARAVIRT_PATCH(irq_enable_sysexit)] = { start_sti_sysexit, end_sti_sysexit },
 };
 
 static unsigned native_patch(u8 type, u16 clobbers, void *insns, unsigned len)
diff --git a/arch/i386/kernel/vmi.c b/arch/i386/kernel/vmi.c
index ea77d93f59dd..b8d01c3cbff4 100644
--- a/arch/i386/kernel/vmi.c
+++ b/arch/i386/kernel/vmi.c
@@ -83,11 +83,6 @@ extern struct paravirt_patch __start_parainstructions[],
 #define MNEM_JMP  0xe9
 #define MNEM_RET  0xc3
 
-static char irq_save_disable_callout[] = {
-        MNEM_CALL, 0, 0, 0, 0,
-        MNEM_CALL, 0, 0, 0, 0,
-        MNEM_RET
-};
 #define IRQ_PATCH_INT_MASK 0
 #define IRQ_PATCH_DISABLE  5
 
@@ -135,33 +130,17 @@ static unsigned patch_internal(int call, unsigned len, void *insns)
 static unsigned vmi_patch(u8 type, u16 clobbers, void *insns, unsigned len)
 {
         switch (type) {
-                case PARAVIRT_IRQ_DISABLE:
+                case PARAVIRT_PATCH(irq_disable):
                         return patch_internal(VMI_CALL_DisableInterrupts, len, insns);
-                case PARAVIRT_IRQ_ENABLE:
+                case PARAVIRT_PATCH(irq_enable):
                         return patch_internal(VMI_CALL_EnableInterrupts, len, insns);
-                case PARAVIRT_RESTORE_FLAGS:
+                case PARAVIRT_PATCH(restore_fl):
                         return patch_internal(VMI_CALL_SetInterruptMask, len, insns);
-                case PARAVIRT_SAVE_FLAGS:
+                case PARAVIRT_PATCH(save_fl):
                         return patch_internal(VMI_CALL_GetInterruptMask, len, insns);
-                case PARAVIRT_SAVE_FLAGS_IRQ_DISABLE:
-                        if (len >= 10) {
-                                patch_internal(VMI_CALL_GetInterruptMask, len, insns);
-                                patch_internal(VMI_CALL_DisableInterrupts, len-5, insns+5);
-                                return 10;
-                        } else {
-                                /*
-                                 * You bastards didn't leave enough room to
-                                 * patch save_flags_irq_disable inline.  Patch
-                                 * to a helper
-                                 */
-                                BUG_ON(len < 5);
-                                *(char *)insns = MNEM_CALL;
-                                patch_offset(insns, irq_save_disable_callout);
-                                return 5;
-                        }
-                case PARAVIRT_INTERRUPT_RETURN:
+                case PARAVIRT_PATCH(iret):
                         return patch_internal(VMI_CALL_IRET, len, insns);
-                case PARAVIRT_STI_SYSEXIT:
+                case PARAVIRT_PATCH(irq_enable_sysexit):
                         return patch_internal(VMI_CALL_SYSEXIT, len, insns);
                 default:
                         break;
@@ -796,12 +775,6 @@ static inline int __init activate_vmi(void)
         para_fill(irq_disable, DisableInterrupts);
         para_fill(irq_enable, EnableInterrupts);
 
-        /* irq_save_disable !!! sheer pain */
-        patch_offset(&irq_save_disable_callout[IRQ_PATCH_INT_MASK],
-                     (char *)paravirt_ops.save_fl);
-        patch_offset(&irq_save_disable_callout[IRQ_PATCH_DISABLE],
-                     (char *)paravirt_ops.irq_disable);
-
         para_fill(wbinvd, WBINVD);
         para_fill(read_tsc, RDTSC);