sparc64: Fix race in TLB batch processing.
David S. Miller [Fri, 19 Apr 2013 21:26:26 +0000 (17:26 -0400)]
[ Commits f36391d2790d04993f48da6a45810033a2cdf847 and
  f0af97070acbad5d6a361f485828223a4faaa0ee upstream. ]

As reported by Dave Kleikamp, when we emit cross calls to do batched
TLB flush processing we have a race because we do not synchronize on
the sibling cpus completing the cross call.

So meanwhile the TLB batch can be reset (tb->tlb_nr set to zero, etc.)
and either flushes are missed or flushes will flush the wrong
addresses.

Fix this by using generic infrastructure to synchonize on the
completion of the cross call.

This first required getting the flush_tlb_pending() call out from
switch_to() which operates with locks held and interrupts disabled.
The problem is that smp_call_function_many() cannot be invoked with
IRQs disabled and this is explicitly checked for with WARN_ON_ONCE().

We get the batch processing outside of locked IRQ disabled sections by
using some ideas from the powerpc port. Namely, we only batch inside
of arch_{enter,leave}_lazy_mmu_mode() calls.  If we're not in such a
region, we flush TLBs synchronously.

1) Get rid of xcall_flush_tlb_pending and per-cpu type
   implementations.

2) Do TLB batch cross calls instead via:

smp_call_function_many()
tlb_pending_func()
__flush_tlb_pending()

3) Batch only in lazy mmu sequences:

a) Add 'active' member to struct tlb_batch
b) Define __HAVE_ARCH_ENTER_LAZY_MMU_MODE
c) Set 'active' in arch_enter_lazy_mmu_mode()
d) Run batch and clear 'active' in arch_leave_lazy_mmu_mode()
e) Check 'active' in tlb_batch_add_one() and do a synchronous
           flush if it's clear.

4) Add infrastructure for synchronous TLB page flushes.

a) Implement __flush_tlb_page and per-cpu variants, patch
   as needed.
b) Likewise for xcall_flush_tlb_page.
c) Implement smp_flush_tlb_page() to invoke the cross-call.
d) Wire up global_flush_tlb_page() to the right routine based
           upon CONFIG_SMP

5) It turns out that singleton batches are very common, 2 out of every
   3 batch flushes have only a single entry in them.

   The batch flush waiting is very expensive, both because of the poll
   on sibling cpu completeion, as well as because passing the tlb batch
   pointer to the sibling cpus invokes a shared memory dereference.

   Therefore, in flush_tlb_pending(), if there is only one entry in
   the batch perform a completely asynchronous global_flush_tlb_page()
   instead.

Reported-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/sparc/include/asm/pgtable_64.h
arch/sparc/include/asm/switch_to_64.h
arch/sparc/include/asm/tlbflush_64.h
arch/sparc/kernel/smp_64.c
arch/sparc/mm/tlb.c
arch/sparc/mm/tsb.c
arch/sparc/mm/ultra.S

index 76e4a52..656de8b 100644 (file)
@@ -780,6 +780,7 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
        return remap_pfn_range(vma, from, phys_base >> PAGE_SHIFT, size, prot);
 }
 
+#include <asm/tlbflush.h>
 #include <asm-generic/pgtable.h>
 
 /* We provide our own get_unmapped_area to cope with VA holes and
index 7923c4a..9c2a92d 100644 (file)
@@ -18,8 +18,7 @@ do {                                          \
         * and 2 stores in this critical code path.  -DaveM
         */
 #define switch_to(prev, next, last)                                    \
-do {   flush_tlb_pending();                                            \
-       save_and_clear_fpu();                                           \
+do {   save_and_clear_fpu();                                           \
        /* If you are tempted to conditionalize the following */        \
        /* so that ASI is only written if it changes, think again. */   \
        __asm__ __volatile__("wr %%g0, %0, %%asi"                       \
index 2ef4634..f0d6a97 100644 (file)
 struct tlb_batch {
        struct mm_struct *mm;
        unsigned long tlb_nr;
+       unsigned long active;
        unsigned long vaddrs[TLB_BATCH_NR];
 };
 
 extern void flush_tsb_kernel_range(unsigned long start, unsigned long end);
 extern void flush_tsb_user(struct tlb_batch *tb);
+extern void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr);
 
 /* TLB flush operations. */
 
-extern void flush_tlb_pending(void);
+static inline void flush_tlb_mm(struct mm_struct *mm)
+{
+}
+
+static inline void flush_tlb_page(struct vm_area_struct *vma,
+                                 unsigned long vmaddr)
+{
+}
+
+static inline void flush_tlb_range(struct vm_area_struct *vma,
+                                  unsigned long start, unsigned long end)
+{
+}
+
+#define __HAVE_ARCH_ENTER_LAZY_MMU_MODE
 
-#define flush_tlb_range(vma,start,end) \
-       do { (void)(start); flush_tlb_pending(); } while (0)
-#define flush_tlb_page(vma,addr)       flush_tlb_pending()
-#define flush_tlb_mm(mm)               flush_tlb_pending()
+extern void flush_tlb_pending(void);
+extern void arch_enter_lazy_mmu_mode(void);
+extern void arch_leave_lazy_mmu_mode(void);
+#define arch_flush_lazy_mmu_mode()      do {} while (0)
 
 /* Local cpu only.  */
 extern void __flush_tlb_all(void);
-
+extern void __flush_tlb_page(unsigned long context, unsigned long vaddr);
 extern void __flush_tlb_kernel_range(unsigned long start, unsigned long end);
 
 #ifndef CONFIG_SMP
@@ -38,15 +54,24 @@ do {        flush_tsb_kernel_range(start,end); \
        __flush_tlb_kernel_range(start,end); \
 } while (0)
 
+static inline void global_flush_tlb_page(struct mm_struct *mm, unsigned long vaddr)
+{
+       __flush_tlb_page(CTX_HWBITS(mm->context), vaddr);
+}
+
 #else /* CONFIG_SMP */
 
 extern void smp_flush_tlb_kernel_range(unsigned long start, unsigned long end);
+extern void smp_flush_tlb_page(struct mm_struct *mm, unsigned long vaddr);
 
 #define flush_tlb_kernel_range(start, end) \
 do {   flush_tsb_kernel_range(start,end); \
        smp_flush_tlb_kernel_range(start, end); \
 } while (0)
 
+#define global_flush_tlb_page(mm, vaddr) \
+       smp_flush_tlb_page(mm, vaddr)
+
 #endif /* ! CONFIG_SMP */
 
 #endif /* _SPARC64_TLBFLUSH_H */
index 3b1bd7c..bb2886a 100644 (file)
@@ -856,7 +856,7 @@ void smp_tsb_sync(struct mm_struct *mm)
 }
 
 extern unsigned long xcall_flush_tlb_mm;
-extern unsigned long xcall_flush_tlb_pending;
+extern unsigned long xcall_flush_tlb_page;
 extern unsigned long xcall_flush_tlb_kernel_range;
 extern unsigned long xcall_fetch_glob_regs;
 extern unsigned long xcall_receive_signal;
@@ -1070,23 +1070,56 @@ local_flush_and_out:
        put_cpu();
 }
 
+struct tlb_pending_info {
+       unsigned long ctx;
+       unsigned long nr;
+       unsigned long *vaddrs;
+};
+
+static void tlb_pending_func(void *info)
+{
+       struct tlb_pending_info *t = info;
+
+       __flush_tlb_pending(t->ctx, t->nr, t->vaddrs);
+}
+
 void smp_flush_tlb_pending(struct mm_struct *mm, unsigned long nr, unsigned long *vaddrs)
 {
        u32 ctx = CTX_HWBITS(mm->context);
+       struct tlb_pending_info info;
        int cpu = get_cpu();
 
+       info.ctx = ctx;
+       info.nr = nr;
+       info.vaddrs = vaddrs;
+
        if (mm == current->mm && atomic_read(&mm->mm_users) == 1)
                cpumask_copy(mm_cpumask(mm), cpumask_of(cpu));
        else
-               smp_cross_call_masked(&xcall_flush_tlb_pending,
-                                     ctx, nr, (unsigned long) vaddrs,
-                                     mm_cpumask(mm));
+               smp_call_function_many(mm_cpumask(mm), tlb_pending_func,
+                                      &info, 1);
 
        __flush_tlb_pending(ctx, nr, vaddrs);
 
        put_cpu();
 }
 
+void smp_flush_tlb_page(struct mm_struct *mm, unsigned long vaddr)
+{
+       unsigned long context = CTX_HWBITS(mm->context);
+       int cpu = get_cpu();
+
+       if (mm == current->mm && atomic_read(&mm->mm_users) == 1)
+               cpumask_copy(mm_cpumask(mm), cpumask_of(cpu));
+       else
+               smp_cross_call_masked(&xcall_flush_tlb_page,
+                                     context, vaddr, 0,
+                                     mm_cpumask(mm));
+       __flush_tlb_page(context, vaddr);
+
+       put_cpu();
+}
+
 void smp_flush_tlb_kernel_range(unsigned long start, unsigned long end)
 {
        start &= PAGE_MASK;
index b1f279c..afd021e 100644 (file)
@@ -24,11 +24,17 @@ static DEFINE_PER_CPU(struct tlb_batch, tlb_batch);
 void flush_tlb_pending(void)
 {
        struct tlb_batch *tb = &get_cpu_var(tlb_batch);
+       struct mm_struct *mm = tb->mm;
 
-       if (tb->tlb_nr) {
-               flush_tsb_user(tb);
+       if (!tb->tlb_nr)
+               goto out;
 
-               if (CTX_VALID(tb->mm->context)) {
+       flush_tsb_user(tb);
+
+       if (CTX_VALID(mm->context)) {
+               if (tb->tlb_nr == 1) {
+                       global_flush_tlb_page(mm, tb->vaddrs[0]);
+               } else {
 #ifdef CONFIG_SMP
                        smp_flush_tlb_pending(tb->mm, tb->tlb_nr,
                                              &tb->vaddrs[0]);
@@ -37,12 +43,30 @@ void flush_tlb_pending(void)
                                            tb->tlb_nr, &tb->vaddrs[0]);
 #endif
                }
-               tb->tlb_nr = 0;
        }
 
+       tb->tlb_nr = 0;
+
+out:
        put_cpu_var(tlb_batch);
 }
 
+void arch_enter_lazy_mmu_mode(void)
+{
+       struct tlb_batch *tb = &__get_cpu_var(tlb_batch);
+
+       tb->active = 1;
+}
+
+void arch_leave_lazy_mmu_mode(void)
+{
+       struct tlb_batch *tb = &__get_cpu_var(tlb_batch);
+
+       if (tb->tlb_nr)
+               flush_tlb_pending();
+       tb->active = 0;
+}
+
 void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr,
                   pte_t *ptep, pte_t orig, int fullmm)
 {
@@ -90,6 +114,12 @@ no_cache_flush:
                nr = 0;
        }
 
+       if (!tb->active) {
+               global_flush_tlb_page(mm, vaddr);
+               flush_tsb_user_page(mm, vaddr);
+               goto out;
+       }
+
        if (nr == 0)
                tb->mm = mm;
 
@@ -98,5 +128,6 @@ no_cache_flush:
        if (nr >= TLB_BATCH_NR)
                flush_tlb_pending();
 
+out:
        put_cpu_var(tlb_batch);
 }
index c52add7..f4e84f3 100644 (file)
@@ -7,11 +7,10 @@
 #include <linux/preempt.h>
 #include <linux/slab.h>
 #include <asm/page.h>
-#include <asm/tlbflush.h>
-#include <asm/tlb.h>
-#include <asm/mmu_context.h>
 #include <asm/pgtable.h>
+#include <asm/mmu_context.h>
 #include <asm/tsb.h>
+#include <asm/tlb.h>
 #include <asm/oplib.h>
 
 extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];
@@ -46,23 +45,27 @@ void flush_tsb_kernel_range(unsigned long start, unsigned long end)
        }
 }
 
-static void __flush_tsb_one(struct tlb_batch *tb, unsigned long hash_shift,
-                           unsigned long tsb, unsigned long nentries)
+static void __flush_tsb_one_entry(unsigned long tsb, unsigned long v,
+                                 unsigned long hash_shift,
+                                 unsigned long nentries)
 {
-       unsigned long i;
+       unsigned long tag, ent, hash;
 
-       for (i = 0; i < tb->tlb_nr; i++) {
-               unsigned long v = tb->vaddrs[i];
-               unsigned long tag, ent, hash;
+       v &= ~0x1UL;
+       hash = tsb_hash(v, hash_shift, nentries);
+       ent = tsb + (hash * sizeof(struct tsb));
+       tag = (v >> 22UL);
 
-               v &= ~0x1UL;
+       tsb_flush(ent, tag);
+}
 
-               hash = tsb_hash(v, hash_shift, nentries);
-               ent = tsb + (hash * sizeof(struct tsb));
-               tag = (v >> 22UL);
+static void __flush_tsb_one(struct tlb_batch *tb, unsigned long hash_shift,
+                           unsigned long tsb, unsigned long nentries)
+{
+       unsigned long i;
 
-               tsb_flush(ent, tag);
-       }
+       for (i = 0; i < tb->tlb_nr; i++)
+               __flush_tsb_one_entry(tsb, tb->vaddrs[i], hash_shift, nentries);
 }
 
 void flush_tsb_user(struct tlb_batch *tb)
@@ -90,6 +93,30 @@ void flush_tsb_user(struct tlb_batch *tb)
        spin_unlock_irqrestore(&mm->context.lock, flags);
 }
 
+void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr)
+{
+       unsigned long nentries, base, flags;
+
+       spin_lock_irqsave(&mm->context.lock, flags);
+
+       base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
+       nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
+       if (tlb_type == cheetah_plus || tlb_type == hypervisor)
+               base = __pa(base);
+       __flush_tsb_one_entry(base, vaddr, PAGE_SHIFT, nentries);
+
+#if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
+       if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
+               base = (unsigned long) mm->context.tsb_block[MM_TSB_HUGE].tsb;
+               nentries = mm->context.tsb_block[MM_TSB_HUGE].tsb_nentries;
+               if (tlb_type == cheetah_plus || tlb_type == hypervisor)
+                       base = __pa(base);
+               __flush_tsb_one_entry(base, vaddr, HPAGE_SHIFT, nentries);
+       }
+#endif
+       spin_unlock_irqrestore(&mm->context.lock, flags);
+}
+
 #if defined(CONFIG_SPARC64_PAGE_SIZE_8KB)
 #define HV_PGSZ_IDX_BASE       HV_PGSZ_IDX_8K
 #define HV_PGSZ_MASK_BASE      HV_PGSZ_MASK_8K
index 874162a..dd10caa 100644 (file)
@@ -53,6 +53,33 @@ __flush_tlb_mm:              /* 18 insns */
        nop
 
        .align          32
+       .globl          __flush_tlb_page
+__flush_tlb_page:      /* 22 insns */
+       /* %o0 = context, %o1 = vaddr */
+       rdpr            %pstate, %g7
+       andn            %g7, PSTATE_IE, %g2
+       wrpr            %g2, %pstate
+       mov             SECONDARY_CONTEXT, %o4
+       ldxa            [%o4] ASI_DMMU, %g2
+       stxa            %o0, [%o4] ASI_DMMU
+       andcc           %o1, 1, %g0
+       andn            %o1, 1, %o3
+       be,pn           %icc, 1f
+        or             %o3, 0x10, %o3
+       stxa            %g0, [%o3] ASI_IMMU_DEMAP
+1:     stxa            %g0, [%o3] ASI_DMMU_DEMAP
+       membar          #Sync
+       stxa            %g2, [%o4] ASI_DMMU
+       sethi           %hi(KERNBASE), %o4
+       flush           %o4
+       retl
+        wrpr           %g7, 0x0, %pstate
+       nop
+       nop
+       nop
+       nop
+
+       .align          32
        .globl          __flush_tlb_pending
 __flush_tlb_pending:   /* 26 insns */
        /* %o0 = context, %o1 = nr, %o2 = vaddrs[] */
@@ -203,6 +230,31 @@ __cheetah_flush_tlb_mm: /* 19 insns */
        retl
         wrpr           %g7, 0x0, %pstate
 
+__cheetah_flush_tlb_page:      /* 22 insns */
+       /* %o0 = context, %o1 = vaddr */
+       rdpr            %pstate, %g7
+       andn            %g7, PSTATE_IE, %g2
+       wrpr            %g2, 0x0, %pstate
+       wrpr            %g0, 1, %tl
+       mov             PRIMARY_CONTEXT, %o4
+       ldxa            [%o4] ASI_DMMU, %g2
+       srlx            %g2, CTX_PGSZ1_NUC_SHIFT, %o3
+       sllx            %o3, CTX_PGSZ1_NUC_SHIFT, %o3
+       or              %o0, %o3, %o0   /* Preserve nucleus page size fields */
+       stxa            %o0, [%o4] ASI_DMMU
+       andcc           %o1, 1, %g0
+       be,pn           %icc, 1f
+        andn           %o1, 1, %o3
+       stxa            %g0, [%o3] ASI_IMMU_DEMAP
+1:     stxa            %g0, [%o3] ASI_DMMU_DEMAP
+       membar          #Sync
+       stxa            %g2, [%o4] ASI_DMMU
+       sethi           %hi(KERNBASE), %o4
+       flush           %o4
+       wrpr            %g0, 0, %tl
+       retl
+        wrpr           %g7, 0x0, %pstate
+
 __cheetah_flush_tlb_pending:   /* 27 insns */
        /* %o0 = context, %o1 = nr, %o2 = vaddrs[] */
        rdpr            %pstate, %g7
@@ -269,6 +321,20 @@ __hypervisor_flush_tlb_mm: /* 10 insns */
        retl
         nop
 
+__hypervisor_flush_tlb_page: /* 11 insns */
+       /* %o0 = context, %o1 = vaddr */
+       mov             %o0, %g2
+       mov             %o1, %o0              /* ARG0: vaddr + IMMU-bit */
+       mov             %g2, %o1              /* ARG1: mmu context */
+       mov             HV_MMU_ALL, %o2       /* ARG2: flags */
+       srlx            %o0, PAGE_SHIFT, %o0
+       sllx            %o0, PAGE_SHIFT, %o0
+       ta              HV_MMU_UNMAP_ADDR_TRAP
+       brnz,pn         %o0, __hypervisor_tlb_tl0_error
+        mov            HV_MMU_UNMAP_ADDR_TRAP, %o1
+       retl
+        nop
+
 __hypervisor_flush_tlb_pending: /* 16 insns */
        /* %o0 = context, %o1 = nr, %o2 = vaddrs[] */
        sllx            %o1, 3, %g1
@@ -339,6 +405,13 @@ cheetah_patch_cachetlbops:
        call            tlb_patch_one
         mov            19, %o2
 
+       sethi           %hi(__flush_tlb_page), %o0
+       or              %o0, %lo(__flush_tlb_page), %o0
+       sethi           %hi(__cheetah_flush_tlb_page), %o1
+       or              %o1, %lo(__cheetah_flush_tlb_page), %o1
+       call            tlb_patch_one
+        mov            22, %o2
+
        sethi           %hi(__flush_tlb_pending), %o0
        or              %o0, %lo(__flush_tlb_pending), %o0
        sethi           %hi(__cheetah_flush_tlb_pending), %o1
@@ -397,10 +470,9 @@ xcall_flush_tlb_mm:        /* 21 insns */
        nop
        nop
 
-       .globl          xcall_flush_tlb_pending
-xcall_flush_tlb_pending:       /* 21 insns */
-       /* %g5=context, %g1=nr, %g7=vaddrs[] */
-       sllx            %g1, 3, %g1
+       .globl          xcall_flush_tlb_page
+xcall_flush_tlb_page:  /* 17 insns */
+       /* %g5=context, %g1=vaddr */
        mov             PRIMARY_CONTEXT, %g4
        ldxa            [%g4] ASI_DMMU, %g2
        srlx            %g2, CTX_PGSZ1_NUC_SHIFT, %g4
@@ -408,20 +480,16 @@ xcall_flush_tlb_pending:  /* 21 insns */
        or              %g5, %g4, %g5
        mov             PRIMARY_CONTEXT, %g4
        stxa            %g5, [%g4] ASI_DMMU
-1:     sub             %g1, (1 << 3), %g1
-       ldx             [%g7 + %g1], %g5
-       andcc           %g5, 0x1, %g0
+       andcc           %g1, 0x1, %g0
        be,pn           %icc, 2f
-
-        andn           %g5, 0x1, %g5
+        andn           %g1, 0x1, %g5
        stxa            %g0, [%g5] ASI_IMMU_DEMAP
 2:     stxa            %g0, [%g5] ASI_DMMU_DEMAP
        membar          #Sync
-       brnz,pt         %g1, 1b
-        nop
        stxa            %g2, [%g4] ASI_DMMU
        retry
        nop
+       nop
 
        .globl          xcall_flush_tlb_kernel_range
 xcall_flush_tlb_kernel_range:  /* 25 insns */
@@ -596,15 +664,13 @@ __hypervisor_xcall_flush_tlb_mm: /* 21 insns */
        membar          #Sync
        retry
 
-       .globl          __hypervisor_xcall_flush_tlb_pending
-__hypervisor_xcall_flush_tlb_pending: /* 21 insns */
-       /* %g5=ctx, %g1=nr, %g7=vaddrs[], %g2,%g3,%g4,g6=scratch */
-       sllx            %g1, 3, %g1
+       .globl          __hypervisor_xcall_flush_tlb_page
+__hypervisor_xcall_flush_tlb_page: /* 17 insns */
+       /* %g5=ctx, %g1=vaddr */
        mov             %o0, %g2
        mov             %o1, %g3
        mov             %o2, %g4
-1:     sub             %g1, (1 << 3), %g1
-       ldx             [%g7 + %g1], %o0        /* ARG0: virtual address */
+       mov             %g1, %o0                /* ARG0: virtual address */
        mov             %g5, %o1                /* ARG1: mmu context */
        mov             HV_MMU_ALL, %o2         /* ARG2: flags */
        srlx            %o0, PAGE_SHIFT, %o0
@@ -613,8 +679,6 @@ __hypervisor_xcall_flush_tlb_pending: /* 21 insns */
        mov             HV_MMU_UNMAP_ADDR_TRAP, %g6
        brnz,a,pn       %o0, __hypervisor_tlb_xcall_error
         mov            %o0, %g5
-       brnz,pt         %g1, 1b
-        nop
        mov             %g2, %o0
        mov             %g3, %o1
        mov             %g4, %o2
@@ -697,6 +761,13 @@ hypervisor_patch_cachetlbops:
        call            tlb_patch_one
         mov            10, %o2
 
+       sethi           %hi(__flush_tlb_page), %o0
+       or              %o0, %lo(__flush_tlb_page), %o0
+       sethi           %hi(__hypervisor_flush_tlb_page), %o1
+       or              %o1, %lo(__hypervisor_flush_tlb_page), %o1
+       call            tlb_patch_one
+        mov            11, %o2
+
        sethi           %hi(__flush_tlb_pending), %o0
        or              %o0, %lo(__flush_tlb_pending), %o0
        sethi           %hi(__hypervisor_flush_tlb_pending), %o1
@@ -728,12 +799,12 @@ hypervisor_patch_cachetlbops:
        call            tlb_patch_one
         mov            21, %o2
 
-       sethi           %hi(xcall_flush_tlb_pending), %o0
-       or              %o0, %lo(xcall_flush_tlb_pending), %o0
-       sethi           %hi(__hypervisor_xcall_flush_tlb_pending), %o1
-       or              %o1, %lo(__hypervisor_xcall_flush_tlb_pending), %o1
+       sethi           %hi(xcall_flush_tlb_page), %o0
+       or              %o0, %lo(xcall_flush_tlb_page), %o0
+       sethi           %hi(__hypervisor_xcall_flush_tlb_page), %o1
+       or              %o1, %lo(__hypervisor_xcall_flush_tlb_page), %o1
        call            tlb_patch_one
-        mov            21, %o2
+        mov            17, %o2
 
        sethi           %hi(xcall_flush_tlb_kernel_range), %o0
        or              %o0, %lo(xcall_flush_tlb_kernel_range), %o0