1 files changed, 153 insertions, 36 deletions

diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index a7551a44686f..081194751ade 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -3,8 +3,26 @@
 /* Various instructions on x86 need to be replaced for
  * para-virtualization: those hooks are defined here. */
 #include <linux/linkage.h>
+#include <linux/stringify.h>
 
 #ifdef CONFIG_PARAVIRT
+/* These are the most performance critical ops, so we want to be able to patch
+ * callers */
+#define PARAVIRT_IRQ_DISABLE 0
+#define PARAVIRT_IRQ_ENABLE 1
+#define PARAVIRT_RESTORE_FLAGS 2
+#define PARAVIRT_SAVE_FLAGS 3
+#define PARAVIRT_SAVE_FLAGS_IRQ_DISABLE 4
+#define PARAVIRT_INTERRUPT_RETURN 5
+#define PARAVIRT_STI_SYSEXIT 6
+
+/* Bitmask of what can be clobbered: usually at least eax. */
+#define CLBR_NONE 0x0
+#define CLBR_EAX 0x1
+#define CLBR_ECX 0x2
+#define CLBR_EDX 0x4
+#define CLBR_ANY 0x7
+
 #ifndef __ASSEMBLY__
 struct thread_struct;
 struct Xgt_desc_struct;
@@ -15,6 +33,15 @@ struct paravirt_ops
         int paravirt_enabled;
         const char *name;
 
+        /*
+         * Patch may replace one of the defined code sequences with arbitrary
+         * code, subject to the same register constraints.  This generally
+         * means the code is not free to clobber any registers other than EAX.
+         * The patch function should return the number of bytes of code
+         * generated, as we nop pad the rest in generic code.
+         */
+        unsigned (*patch)(u8 type, u16 clobber, void *firstinsn, unsigned len);
+
         void (*arch_setup)(void);
         char *(*memory_setup)(void);
         void (*init_IRQ)(void);
@@ -147,35 +174,6 @@ static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
 #define read_cr4_safe(x) paravirt_ops.read_cr4_safe()
 #define write_cr4(x) paravirt_ops.write_cr4(x)
 
-static inline unsigned long __raw_local_save_flags(void)
-{
-        return paravirt_ops.save_fl();
-}
-
-static inline void raw_local_irq_restore(unsigned long flags)
-{
-        return paravirt_ops.restore_fl(flags);
-}
-
-static inline void raw_local_irq_disable(void)
-{
-        paravirt_ops.irq_disable();
-}
-
-static inline void raw_local_irq_enable(void)
-{
-        paravirt_ops.irq_enable();
-}
-
-static inline unsigned long __raw_local_irq_save(void)
-{
-        unsigned long flags = paravirt_ops.save_fl();
-
-        paravirt_ops.irq_disable();
-
-        return flags;
-}
-
 static inline void raw_safe_halt(void)
 {
         paravirt_ops.safe_halt();
@@ -267,15 +265,134 @@ static inline void slow_down_io(void) {
 #endif
 }
 
-#define CLI_STRING      "pushl %eax; pushl %ecx; pushl %edx; call *paravirt_ops+PARAVIRT_irq_disable; popl %edx; popl %ecx; popl %eax"
-#define STI_STRING      "pushl %eax; pushl %ecx; pushl %edx; call *paravirt_ops+PARAVIRT_irq_enable; popl %edx; popl %ecx; popl %eax"
+/* These all sit in the .parainstructions section to tell us what to patch. */
+struct paravirt_patch {
+        u8 *instr;              /* original instructions */
+        u8 instrtype;           /* type of this instruction */
+        u8 len;                 /* length of original instruction */
+        u16 clobbers;           /* what registers you may clobber */
+};
+
+#define paravirt_alt(insn_string, typenum, clobber)     \
+        "771:\n\t" insn_string "\n" "772:\n"            \
+        ".pushsection .parainstructions,\"a\"\n"        \
+        "  .long 771b\n"                                \
+        "  .byte " __stringify(typenum) "\n"            \
+        "  .byte 772b-771b\n"                           \
+        "  .short " __stringify(clobber) "\n"           \
+        ".popsection"
+
+static inline unsigned long __raw_local_save_flags(void)
+{
+        unsigned long f;
+
+        __asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
+                                           "call *%1;"
+                                           "popl %%edx; popl %%ecx",
+                                          PARAVIRT_SAVE_FLAGS, CLBR_NONE)
+                             : "=a"(f): "m"(paravirt_ops.save_fl)
+                             : "memory", "cc");
+        return f;
+}
+
+static inline void raw_local_irq_restore(unsigned long f)
+{
+        __asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
+                                           "call *%1;"
+                                           "popl %%edx; popl %%ecx",
+                                          PARAVIRT_RESTORE_FLAGS, CLBR_EAX)
+                             : "=a"(f) : "m" (paravirt_ops.restore_fl), "0"(f)
+                             : "memory", "cc");
+}
+
+static inline void raw_local_irq_disable(void)
+{
+        __asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
+                                           "call *%0;"
+                                           "popl %%edx; popl %%ecx",
+                                          PARAVIRT_IRQ_DISABLE, CLBR_EAX)
+                             : : "m" (paravirt_ops.irq_disable)
+                             : "memory", "eax", "cc");
+}
+
+static inline void raw_local_irq_enable(void)
+{
+        __asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
+                                           "call *%0;"
+                                           "popl %%edx; popl %%ecx",
+                                          PARAVIRT_IRQ_ENABLE, CLBR_EAX)
+                             : : "m" (paravirt_ops.irq_enable)
+                             : "memory", "eax", "cc");
+}
+
+static inline unsigned long __raw_local_irq_save(void)
+{
+        unsigned long f;
+
+        __asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
+                                           "call *%1; pushl %%eax;"
+                                           "call *%2; popl %%eax;"
+                                           "popl %%edx; popl %%ecx",
+                                          PARAVIRT_SAVE_FLAGS_IRQ_DISABLE,
+                                          CLBR_NONE)
+                             : "=a"(f)
+                             : "m" (paravirt_ops.save_fl),
+                               "m" (paravirt_ops.irq_disable)
+                             : "memory", "cc");
+        return f;
+}
+
+#define CLI_STRING paravirt_alt("pushl %%ecx; pushl %%edx;"             \
+                     "call *paravirt_ops+%c[irq_disable];"              \
+                     "popl %%edx; popl %%ecx",                          \
+                     PARAVIRT_IRQ_DISABLE, CLBR_EAX)
+
+#define STI_STRING paravirt_alt("pushl %%ecx; pushl %%edx;"             \
+                     "call *paravirt_ops+%c[irq_enable];"               \
+                     "popl %%edx; popl %%ecx",                          \
+                     PARAVIRT_IRQ_ENABLE, CLBR_EAX)
+#define CLI_STI_CLOBBERS , "%eax"
+#define CLI_STI_INPUT_ARGS \
+        ,                                                               \
+        [irq_disable] "i" (offsetof(struct paravirt_ops, irq_disable)), \
+        [irq_enable] "i" (offsetof(struct paravirt_ops, irq_enable))
+
 #else  /* __ASSEMBLY__ */
 
-#define INTERRUPT_RETURN        jmp *%cs:paravirt_ops+PARAVIRT_iret
-#define DISABLE_INTERRUPTS      pushl %eax; pushl %ecx; pushl %edx; call *paravirt_ops+PARAVIRT_irq_disable; popl %edx; popl %ecx; popl %eax
-#define ENABLE_INTERRUPTS       pushl %eax; pushl %ecx; pushl %edx; call *%cs:paravirt_ops+PARAVIRT_irq_enable; popl %edx; popl %ecx; popl %eax
-#define ENABLE_INTERRUPTS_SYSEXIT       jmp *%cs:paravirt_ops+PARAVIRT_irq_enable_sysexit
-#define GET_CR0_INTO_EAX        call *paravirt_ops+PARAVIRT_read_cr0
+#define PARA_PATCH(ptype, clobbers, ops)        \
+771:;                                           \
+        ops;                                    \
+772:;                                           \
+        .pushsection .parainstructions,"a";     \
+         .long 771b;                            \
+         .byte ptype;                           \
+         .byte 772b-771b;                       \
+         .short clobbers;                       \
+        .popsection
+
+#define INTERRUPT_RETURN                                \
+        PARA_PATCH(PARAVIRT_INTERRUPT_RETURN, CLBR_ANY, \
+        jmp *%cs:paravirt_ops+PARAVIRT_iret)
+
+#define DISABLE_INTERRUPTS(clobbers)                    \
+        PARA_PATCH(PARAVIRT_IRQ_DISABLE, clobbers,      \
+        pushl %ecx; pushl %edx;                         \
+        call *paravirt_ops+PARAVIRT_irq_disable;        \
+        popl %edx; popl %ecx)                           \
+
+#define ENABLE_INTERRUPTS(clobbers)                     \
+        PARA_PATCH(PARAVIRT_IRQ_ENABLE, clobbers,       \
+        pushl %ecx; pushl %edx;                         \
+        call *%cs:paravirt_ops+PARAVIRT_irq_enable;     \
+        popl %edx; popl %ecx)
+
+#define ENABLE_INTERRUPTS_SYSEXIT                       \
+        PARA_PATCH(PARAVIRT_STI_SYSEXIT, CLBR_ANY,      \
+        jmp *%cs:paravirt_ops+PARAVIRT_irq_enable_sysexit)
+
+#define GET_CR0_INTO_EAX                        \
+        call *paravirt_ops+PARAVIRT_read_cr0
+
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_PARAVIRT */
 #endif  /* __ASM_PARAVIRT_H */