[PATCH] paravirt: Patch inline replacements for paravirt intercepts

It turns out that the most called ops, by several orders of magnitude,
are the interrupt manipulation ops.  These are obvious candidates for
patching, so mark them up and create infrastructure for it.

The method used is that the ops structure has a patch function, which
is called for each place which needs to be patched: this returns a
number of instructions (the rest are NOP-padded).

Usually we can spare a register (%eax) for the binary patched code to
use, but in a couple of critical places in entry.S we can't: we make
the clobbers explicit at the call site, and manually clobber the
allowed registers in debug mode as an extra check.

And:

Don't abuse CONFIG_DEBUG_KERNEL, add CONFIG_DEBUG_PARAVIRT.

And:

AK:  Fix warnings in x86-64 alternative.c build

And:

AK: Fix compilation with defconfig

And:

^From: Andrew Morton <akpm@osdl.org>

Some binutlises still like to emit references to __stop_parainstructions and
__start_parainstructions.

And:

AK: Fix warnings about unused variables when PARAVIRT is disabled.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>

6 files changed, 297 insertions, 163 deletions

diff --git a/include/asm-i386/alternative.h b/include/asm-i386/alternative.h
index b01a7ec409c..b8fa9557c53 100644
--- a/include/asm-i386/alternative.h
+++ b/include/asm-i386/alternative.h
@@ -4,7 +4,7 @@
 #ifdef __KERNEL__
 
 #include <asm/types.h>
-
+#include <linux/stddef.h>
 #include <linux/types.h>
 
 struct alt_instr {
@@ -118,4 +118,15 @@ static inline void alternatives_smp_switch(int smp) {}
 #define LOCK_PREFIX ""
 #endif
 
+struct paravirt_patch;
+#ifdef CONFIG_PARAVIRT
+void apply_paravirt(struct paravirt_patch *start, struct paravirt_patch *end);
+#else
+static inline void
+apply_paravirt(struct paravirt_patch *start, struct paravirt_patch *end)
+{}
+#define __start_parainstructions NULL
+#define __stop_parainstructions NULL
+#endif
+
 #endif /* _I386_ALTERNATIVE_H */
diff --git a/include/asm-i386/desc.h b/include/asm-i386/desc.h
index f19820f0834..f398cc45644 100644
--- a/include/asm-i386/desc.h
+++ b/include/asm-i386/desc.h
@@ -81,31 +81,15 @@ static inline void load_TLS(struct thread_struct *t, unsigned int cpu)
 #undef C
 }
 
-static inline void write_dt_entry(void *dt, int entry, __u32 entry_a, __u32 entry_b)
-{
-        __u32 *lp = (__u32 *)((char *)dt + entry*8);
-        *lp = entry_a;
-        *(lp+1) = entry_b;
-}
-
 #define write_ldt_entry(dt, entry, a, b) write_dt_entry(dt, entry, a, b)
 #define write_gdt_entry(dt, entry, a, b) write_dt_entry(dt, entry, a, b)
 #define write_idt_entry(dt, entry, a, b) write_dt_entry(dt, entry, a, b)
 
-static inline void _set_gate(int gate, unsigned int type, void *addr, unsigned short seg)
-{
-        __u32 a, b;
-        pack_gate(&a, &b, (unsigned long)addr, seg, type, 0);
-        write_idt_entry(idt_table, gate, a, b);
-}
-
-static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, const void *addr)
+static inline void write_dt_entry(void *dt, int entry, __u32 entry_a, __u32 entry_b)
 {
-        __u32 a, b;
-        pack_descriptor(&a, &b, (unsigned long)addr,
-                        offsetof(struct tss_struct, __cacheline_filler) - 1,
-                        DESCTYPE_TSS, 0);
-        write_gdt_entry(get_cpu_gdt_table(cpu), entry, a, b);
+        __u32 *lp = (__u32 *)((char *)dt + entry*8);
+        *lp = entry_a;
+        *(lp+1) = entry_b;
 }
 
 #define set_ldt native_set_ldt
@@ -128,6 +112,23 @@ static inline fastcall void native_set_ldt(const void *addr,
         }
 }
 
+static inline void _set_gate(int gate, unsigned int type, void *addr, unsigned short seg)
+{
+        __u32 a, b;
+        pack_gate(&a, &b, (unsigned long)addr, seg, type, 0);
+        write_idt_entry(idt_table, gate, a, b);
+}
+
+static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, const void *addr)
+{
+        __u32 a, b;
+        pack_descriptor(&a, &b, (unsigned long)addr,
+                        offsetof(struct tss_struct, __cacheline_filler) - 1,
+                        DESCTYPE_TSS, 0);
+        write_gdt_entry(get_cpu_gdt_table(cpu), entry, a, b);
+}
+
+
 #define set_tss_desc(cpu,addr) __set_tss_desc(cpu, GDT_ENTRY_TSS, addr)
 
 #define LDT_entry_a(info) \
diff --git a/include/asm-i386/irqflags.h b/include/asm-i386/irqflags.h
index 9ce01f3fb7b..17b18cf4fe9 100644
--- a/include/asm-i386/irqflags.h
+++ b/include/asm-i386/irqflags.h
@@ -79,8 +79,8 @@ static inline unsigned long __raw_local_irq_save(void)
 }
 
 #else
-#define DISABLE_INTERRUPTS              cli
-#define ENABLE_INTERRUPTS               sti
+#define DISABLE_INTERRUPTS(clobbers)    cli
+#define ENABLE_INTERRUPTS(clobbers)     sti
 #define ENABLE_INTERRUPTS_SYSEXIT       sti; sysexit
 #define INTERRUPT_RETURN                iret
 #define GET_CR0_INTO_EAX                movl %cr0, %eax
diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index a7551a44686..081194751ad 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 */
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h
index 6c2c4457be0..5f0418d0078 100644
--- a/include/asm-i386/processor.h
+++ b/include/asm-i386/processor.h
@@ -156,59 +156,6 @@ static inline fastcall void native_cpuid(unsigned int *eax, unsigned int *ebx,
                 : "0" (*eax), "2" (*ecx));
 }
 
-/*
- * Generic CPUID function
- * clear %ecx since some cpus (Cyrix MII) do not set or clear %ecx
- * resulting in stale register contents being returned.
- */
-static inline void cpuid(unsigned int op, unsigned int *eax, unsigned int *ebx, unsigned int *ecx, unsigned int *edx)
-{
-        *eax = op;
-        *ecx = 0;
-        __cpuid(eax, ebx, ecx, edx);
-}
-
-/* Some CPUID calls want 'count' to be placed in ecx */
-static inline void cpuid_count(int op, int count, int *eax, int *ebx, int *ecx,
-                               int *edx)
-{
-        *eax = op;
-        *ecx = count;
-        __cpuid(eax, ebx, ecx, edx);
-}
-
-/*
- * CPUID functions returning a single datum
- */
-static inline unsigned int cpuid_eax(unsigned int op)
-{
-        unsigned int eax, ebx, ecx, edx;
-
-        cpuid(op, &eax, &ebx, &ecx, &edx);
-        return eax;
-}
-static inline unsigned int cpuid_ebx(unsigned int op)
-{
-        unsigned int eax, ebx, ecx, edx;
-
-        cpuid(op, &eax, &ebx, &ecx, &edx);
-        return ebx;
-}
-static inline unsigned int cpuid_ecx(unsigned int op)
-{
-        unsigned int eax, ebx, ecx, edx;
-
-        cpuid(op, &eax, &ebx, &ecx, &edx);
-        return ecx;
-}
-static inline unsigned int cpuid_edx(unsigned int op)
-{
-        unsigned int eax, ebx, ecx, edx;
-
-        cpuid(op, &eax, &ebx, &ecx, &edx);
-        return edx;
-}
-
 #define load_cr3(pgdir) write_cr3(__pa(pgdir))
 
 /*
@@ -491,22 +438,6 @@ struct thread_struct {
         .io_bitmap      = { [ 0 ... IO_BITMAP_LONGS] = ~0 },            \
 }
 
-#ifdef CONFIG_PARAVIRT
-#include <asm/paravirt.h>
-#else
-#define paravirt_enabled() 0
-#define __cpuid native_cpuid
-
-static inline void load_esp0(struct tss_struct *tss, struct thread_struct *thread)
-{
-        tss->esp0 = thread->esp0;
-        /* This can only happen when SEP is enabled, no need to test "SEP"arately */
-        if (unlikely(tss->ss1 != thread->sysenter_cs)) {
-                tss->ss1 = thread->sysenter_cs;
-                wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0);
-        }
-}
-
 #define start_thread(regs, new_eip, new_esp) do {               \
         __asm__("movl %0,%%fs": :"r" (0));                      \
         regs->xgs = 0;                                          \
@@ -519,36 +450,6 @@ static inline void load_esp0(struct tss_struct *tss, struct thread_struct *threa
         regs->esp = new_esp;                                    \
 } while (0)
 
-/*
- * These special macros can be used to get or set a debugging register
- */
-#define get_debugreg(var, register)                             \
-                __asm__("movl %%db" #register ", %0"            \
-                        :"=r" (var))
-#define set_debugreg(value, register)                   \
-                __asm__("movl %0,%%db" #register                \
-                        : /* no output */                       \
-                        :"r" (value))
-
-#define set_iopl_mask native_set_iopl_mask
-#endif /* CONFIG_PARAVIRT */
-
-/*
- * Set IOPL bits in EFLAGS from given mask
- */
-static fastcall inline void native_set_iopl_mask(unsigned mask)
-{
-        unsigned int reg;
-        __asm__ __volatile__ ("pushfl;"
-                              "popl %0;"
-                              "andl %1, %0;"
-                              "orl %2, %0;"
-                              "pushl %0;"
-                              "popfl"
-                                : "=&r" (reg)
-                                : "i" (~X86_EFLAGS_IOPL), "r" (mask));
-}
-
 /* Forward declaration, a strange C thing */
 struct task_struct;
 struct mm_struct;
@@ -640,6 +541,105 @@ static inline void rep_nop(void)
 
 #define cpu_relax()     rep_nop()
 
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#else
+#define paravirt_enabled() 0
+#define __cpuid native_cpuid
+
+static inline void load_esp0(struct tss_struct *tss, struct thread_struct *thread)
+{
+        tss->esp0 = thread->esp0;
+        /* This can only happen when SEP is enabled, no need to test "SEP"arately */
+        if (unlikely(tss->ss1 != thread->sysenter_cs)) {
+                tss->ss1 = thread->sysenter_cs;
+                wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0);
+        }
+}
+
+/*
+ * These special macros can be used to get or set a debugging register
+ */
+#define get_debugreg(var, register)                             \
+                __asm__("movl %%db" #register ", %0"            \
+                        :"=r" (var))
+#define set_debugreg(value, register)                   \
+                __asm__("movl %0,%%db" #register                \
+                        : /* no output */                       \
+                        :"r" (value))
+
+#define set_iopl_mask native_set_iopl_mask
+#endif /* CONFIG_PARAVIRT */
+
+/*
+ * Set IOPL bits in EFLAGS from given mask
+ */
+static fastcall inline void native_set_iopl_mask(unsigned mask)
+{
+        unsigned int reg;
+        __asm__ __volatile__ ("pushfl;"
+                              "popl %0;"
+                              "andl %1, %0;"
+                              "orl %2, %0;"
+                              "pushl %0;"
+                              "popfl"
+                                : "=&r" (reg)
+                                : "i" (~X86_EFLAGS_IOPL), "r" (mask));
+}
+
+/*
+ * Generic CPUID function
+ * clear %ecx since some cpus (Cyrix MII) do not set or clear %ecx
+ * resulting in stale register contents being returned.
+ */
+static inline void cpuid(unsigned int op, unsigned int *eax, unsigned int *ebx, unsigned int *ecx, unsigned int *edx)
+{
+        *eax = op;
+        *ecx = 0;
+        __cpuid(eax, ebx, ecx, edx);
+}
+
+/* Some CPUID calls want 'count' to be placed in ecx */
+static inline void cpuid_count(int op, int count, int *eax, int *ebx, int *ecx,
+                               int *edx)
+{
+        *eax = op;
+        *ecx = count;
+        __cpuid(eax, ebx, ecx, edx);
+}
+
+/*
+ * CPUID functions returning a single datum
+ */
+static inline unsigned int cpuid_eax(unsigned int op)
+{
+        unsigned int eax, ebx, ecx, edx;
+
+        cpuid(op, &eax, &ebx, &ecx, &edx);
+        return eax;
+}
+static inline unsigned int cpuid_ebx(unsigned int op)
+{
+        unsigned int eax, ebx, ecx, edx;
+
+        cpuid(op, &eax, &ebx, &ecx, &edx);
+        return ebx;
+}
+static inline unsigned int cpuid_ecx(unsigned int op)
+{
+        unsigned int eax, ebx, ecx, edx;
+
+        cpuid(op, &eax, &ebx, &ecx, &edx);
+        return ecx;
+}
+static inline unsigned int cpuid_edx(unsigned int op)
+{
+        unsigned int eax, ebx, ecx, edx;
+
+        cpuid(op, &eax, &ebx, &ecx, &edx);
+        return edx;
+}
+
 /* generic versions from gas */
 #define GENERIC_NOP1    ".byte 0x90\n"
 #define GENERIC_NOP2            ".byte 0x89,0xf6\n"
diff --git a/include/asm-i386/spinlock.h b/include/asm-i386/spinlock.h
index dea60709db2..d3bcebed60c 100644
--- a/include/asm-i386/spinlock.h
+++ b/include/asm-i386/spinlock.h
@@ -12,6 +12,8 @@
 #else
 #define CLI_STRING      "cli"
 #define STI_STRING      "sti"
+#define CLI_STI_CLOBBERS
+#define CLI_STI_INPUT_ARGS
 #endif /* CONFIG_PARAVIRT */
 
 /*
@@ -57,25 +59,28 @@ static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long fla
 {
         asm volatile(
                 "\n1:\t"
-                LOCK_PREFIX " ; decb %0\n\t"
+                LOCK_PREFIX " ; decb %[slock]\n\t"
                 "jns 5f\n"
                 "2:\t"
-                "testl $0x200, %1\n\t"
+                "testl $0x200, %[flags]\n\t"
                 "jz 4f\n\t"
                 STI_STRING "\n"
                 "3:\t"
                 "rep;nop\n\t"
-                "cmpb $0, %0\n\t"
+                "cmpb $0, %[slock]\n\t"
                 "jle 3b\n\t"
                 CLI_STRING "\n\t"
                 "jmp 1b\n"
                 "4:\t"
                 "rep;nop\n\t"
-                "cmpb $0, %0\n\t"
+                "cmpb $0, %[slock]\n\t"
                 "jg 1b\n\t"
                 "jmp 4b\n"
                 "5:\n\t"
-                : "+m" (lock->slock) : "r" (flags) : "memory");
+                : [slock] "+m" (lock->slock)
+                : [flags] "r" (flags)
+                  CLI_STI_INPUT_ARGS
+                : "memory" CLI_STI_CLOBBERS);
 }
 #endif