[POWERPC] Add 1TB workaround for PA6T

PA6T has a bug where the slbie instruction does not honor the large
segment bit.  As a result, we have to always use slbia when switching
context.

We don't have to worry about changing the slbie's during fault processing,
since they should never be replacing one VSID with another using the
same ESID.  I.e. there's no risk for inserting duplicate entries due to a
failed slbie of the old entry.  So as long as we clear it out on context
switch we should be fine.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 0ec1340..148a354 100644 (file)
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -408,6 +408,12 @@ END_FTR_SECTION_IFSET(CPU_FTR_1T_SEGMENT)
        std     r7,SLBSHADOW_STACKVSID(r9)  /* Save VSID */
        std     r0,SLBSHADOW_STACKESID(r9)  /* Save ESID */
 
+       /* No need to check for CPU_FTR_NO_SLBIE_B here, since when
+        * we have 1TB segments, the only CPUs known to have the errata
+        * only support less than 1TB of system memory and we'll never
+        * actually hit this code path.
+        */
+
        slbie   r6
        slbie   r6              /* Workaround POWER5 < DD2.1 issue */
        slbmte  r7,r0

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 09da90b..c78dc91 100644 (file)
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -212,6 +212,7 @@ static int __init htab_dt_scan_seg_sizes(unsigned long node,
                        return 1;
                }
        }
+       cur_cpu_spec->cpu_features &= ~CPU_FTR_NO_SLBIE_B;
        return 0;
 }
 

diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 6c164ce..bbd2c51 100644 (file)
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -157,7 +157,8 @@ void switch_slb(struct task_struct *tsk, struct mm_struct *mm)
        unsigned long stack = KSTK_ESP(tsk);
        unsigned long unmapped_base;
 
-       if (offset <= SLB_CACHE_ENTRIES) {
+       if (!cpu_has_feature(CPU_FTR_NO_SLBIE_B) &&
+           offset <= SLB_CACHE_ENTRIES) {
                int i;
                asm volatile("isync" : : : "memory");
                for (i = 0; i < offset; i++) {

diff --git a/include/asm-powerpc/cputable.h b/include/asm-powerpc/cputable.h
index ae093ef..9d74338 100644 (file)
--- a/include/asm-powerpc/cputable.h
+++ b/include/asm-powerpc/cputable.h
@@ -165,6 +165,7 @@ extern void do_feature_fixups(unsigned long value, void *fixup_start,
 #define CPU_FTR_SPURR                  LONG_ASM_CONST(0x0001000000000000)
 #define CPU_FTR_DSCR                   LONG_ASM_CONST(0x0002000000000000)
 #define CPU_FTR_1T_SEGMENT             LONG_ASM_CONST(0x0004000000000000)
+#define CPU_FTR_NO_SLBIE_B             LONG_ASM_CONST(0x0008000000000000)
 
 #ifndef __ASSEMBLY__
 
@@ -367,7 +368,7 @@ extern void do_feature_fixups(unsigned long value, void *fixup_start,
 #define CPU_FTRS_PA6T (CPU_FTR_USE_TB | \
            CPU_FTR_HPTE_TABLE | CPU_FTR_PPCAS_ARCH_V2 | \
            CPU_FTR_ALTIVEC_COMP | CPU_FTR_CI_LARGE_PAGE | \
-           CPU_FTR_PURR | CPU_FTR_REAL_LE)
+           CPU_FTR_PURR | CPU_FTR_REAL_LE | CPU_FTR_NO_SLBIE_B)
 #define CPU_FTRS_COMPATIBLE    (CPU_FTR_USE_TB | \
            CPU_FTR_HPTE_TABLE | CPU_FTR_PPCAS_ARCH_V2)