[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>

1 files changed, 92 insertions, 85 deletions

diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index b4cc2fc4031e..1dbc01f4ed4d 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -4,19 +4,8 @@
  * para-virtualization: those hooks are defined here. */
 
 #ifdef CONFIG_PARAVIRT
-#include <linux/stringify.h>
 #include <asm/page.h>
 
-/* 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
@@ -191,6 +180,28 @@ struct paravirt_ops
 
 extern struct paravirt_ops paravirt_ops;
 
+#define PARAVIRT_PATCH(x)                                       \
+        (offsetof(struct paravirt_ops, x) / sizeof(void *))
+
+#define paravirt_type(type)                                     \
+        [paravirt_typenum] "i" (PARAVIRT_PATCH(type))
+#define paravirt_clobber(clobber)               \
+        [paravirt_clobber] "i" (clobber)
+
+#define PARAVIRT_CALL   "call *paravirt_ops+%c[paravirt_typenum]*4;"
+
+#define _paravirt_alt(insn_string, type, clobber)       \
+        "771:\n\t" insn_string "\n" "772:\n"            \
+        ".pushsection .parainstructions,\"a\"\n"        \
+        "  .long 771b\n"                                \
+        "  .byte " type "\n"                            \
+        "  .byte 772b-771b\n"                           \
+        "  .short " clobber "\n"                        \
+        ".popsection\n"
+
+#define paravirt_alt(insn_string)                               \
+        _paravirt_alt(insn_string, "%c[paravirt_typenum]", "%c[paravirt_clobber]")
+
 #define paravirt_enabled() (paravirt_ops.paravirt_enabled)
 
 static inline void load_esp0(struct tss_struct *tss,
@@ -515,93 +526,89 @@ struct paravirt_patch_site {
 extern struct paravirt_patch_site __parainstructions[],
         __parainstructions_end[];
 
-#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");
+        asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
+                                  PARAVIRT_CALL
+                                  "popl %%edx; popl %%ecx")
+                     : "=a"(f)
+                     : paravirt_type(save_fl),
+                       paravirt_clobber(CLBR_NONE)
+                     : "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");
+        asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
+                                  PARAVIRT_CALL
+                                  "popl %%edx; popl %%ecx")
+                     : "=a"(f)
+                     : "0"(f),
+                       paravirt_type(restore_fl),
+                       paravirt_clobber(CLBR_EAX)
+                     : "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");
+        asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
+                                  PARAVIRT_CALL
+                                  "popl %%edx; popl %%ecx")
+                     :
+                     : paravirt_type(irq_disable),
+                       paravirt_clobber(CLBR_EAX)
+                     : "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");
+        asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
+                                  PARAVIRT_CALL
+                                  "popl %%edx; popl %%ecx")
+                     :
+                     : paravirt_type(irq_enable),
+                       paravirt_clobber(CLBR_EAX)
+                     : "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");
+        f = __raw_local_save_flags();
+        raw_local_irq_disable();
         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 CLI_STRING                                                      \
+        _paravirt_alt("pushl %%ecx; pushl %%edx;"                       \
+                      "call *paravirt_ops+%c[paravirt_cli_type]*4;"     \
+                      "popl %%edx; popl %%ecx",                         \
+                      "%c[paravirt_cli_type]", "%c[paravirt_clobber]")
+
+#define STI_STRING                                                      \
+        _paravirt_alt("pushl %%ecx; pushl %%edx;"                       \
+                      "call *paravirt_ops+%c[paravirt_sti_type]*4;"     \
+                      "popl %%edx; popl %%ecx",                         \
+                      "%c[paravirt_sti_type]", "%c[paravirt_clobber]")
 
-#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 \
+#define CLI_STI_INPUT_ARGS                                              \
         ,                                                               \
-        [irq_disable] "i" (offsetof(struct paravirt_ops, irq_disable)), \
-        [irq_enable] "i" (offsetof(struct paravirt_ops, irq_enable))
+        [paravirt_cli_type] "i" (PARAVIRT_PATCH(irq_disable)),          \
+        [paravirt_sti_type] "i" (PARAVIRT_PATCH(irq_enable)),           \
+        paravirt_clobber(CLBR_EAX)
+
+#undef PARAVIRT_CALL
 
 #else  /* __ASSEMBLY__ */
 
-#define PARA_PATCH(ptype, clobbers, ops)        \
+#define PARA_PATCH(off) ((off) / 4)
+
+#define PARA_SITE(ptype, clobbers, ops)         \
 771:;                                           \
         ops;                                    \
 772:;                                           \
@@ -612,25 +619,25 @@ static inline unsigned long __raw_local_irq_save(void)
          .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 INTERRUPT_RETURN                                        \
+        PARA_SITE(PARA_PATCH(PARAVIRT_iret), CLBR_ANY,          \
+                  jmp *%cs:paravirt_ops+PARAVIRT_iret)
+
+#define DISABLE_INTERRUPTS(clobbers)                                    \
+        PARA_SITE(PARA_PATCH(PARAVIRT_irq_disable), clobbers,           \
+                  pushl %ecx; pushl %edx;                               \
+                  call *%cs:paravirt_ops+PARAVIRT_irq_disable;          \
+                  popl %edx; popl %ecx)                                 \
+
+#define ENABLE_INTERRUPTS(clobbers)                                     \
+        PARA_SITE(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_SITE(PARA_PATCH(PARAVIRT_irq_enable_sysexit), CLBR_ANY,    \
+                  jmp *%cs:paravirt_ops+PARAVIRT_irq_enable_sysexit)
 
 #define GET_CR0_INTO_EAX                        \
         call *paravirt_ops+PARAVIRT_read_cr0