Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=87a72f9e171e558a0288aa83ef1dc6ae4af32224
Commit:     87a72f9e171e558a0288aa83ef1dc6ae4af32224
Parent:     64f2758514e3bad19cab03d22851ab37654399a4
Author:     Paul Mackerras <[EMAIL PROTECTED]>
AuthorDate: Thu Oct 4 14:18:01 2007 +1000
Committer:  Paul Mackerras <[EMAIL PROTECTED]>
CommitDate: Thu Oct 11 21:37:50 2007 +1000

    [POWERPC] Fix performance monitor on machines with logical PVR
    
    Some IBM machines supply a "logical" PVR (processor version register)
    value in the device tree in the cpu nodes rather than the real PVR.
    This is used for instance to indicate that the processors in a POWER6
    partition have been configured by the hypervisor to run in POWER5+
    mode rather than POWER6 mode.  To cope with this, we call identify_cpu
    a second time with the logical PVR value (the first call is with the
    real PVR value in the very early setup code).
    
    However, POWER5+ machines can also supply a logical PVR value, and use
    the same value (the value that indicates a v2.04 architecture
    compliant processor).  This causes problems for code that uses the
    performance monitor (such as oprofile), because the PMU registers are
    different in POWER6 (even in POWER5+ mode) from the real POWER5+.
    
    This change works around this problem by taking out the PMU
    information from the cputable entries for the logical PVR values, and
    changing identify_cpu so that the second call to it won't overwrite
    the PMU information that was established by the first call (the one
    with the real PVR), but does update the other fields.  Specifically,
    if the cputable entry for the logical PVR value has num_pmcs == 0,
    none of the PMU-related fields get used.
    
    So that we can create a mixed cputable entry, we now make cur_cpu_spec
    point to a single static struct cpu_spec, and copy stuff from
    cpu_specs[i] into it.  This has the side-effect that we can now make
    cpu_specs[] be initdata.
    
    Ultimately it would be good to move the PMU-related fields out to a
    separate structure, pointed to by the cputable entries, and change
    identify_cpu so that it saves the PMU info pointer, copies the whole
    structure, and restores the PMU info pointer, rather than identify_cpu
    having to list all the fields that are *not* PMU-related.
    
    Signed-off-by: Paul Mackerras <[EMAIL PROTECTED]>
    Acked-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]>
---
 arch/powerpc/kernel/cputable.c |   45 +++++++++++++++++++++------------------
 include/asm-powerpc/cputable.h |    1 +
 2 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index b03a442..8662cf0 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -71,7 +71,7 @@ extern void __restore_cpu_ppc970(void);
 #define COMMON_USER_BOOKE      (PPC_FEATURE_32 | PPC_FEATURE_HAS_MMU | \
                                 PPC_FEATURE_BOOKE)
 
-static struct cpu_spec cpu_specs[] = {
+static struct cpu_spec __initdata cpu_specs[] = {
 #ifdef CONFIG_PPC64
        {       /* Power3 */
                .pvr_mask               = 0xffff0000,
@@ -327,14 +327,6 @@ static struct cpu_spec cpu_specs[] = {
                .cpu_user_features      = COMMON_USER_POWER5_PLUS,
                .icache_bsize           = 128,
                .dcache_bsize           = 128,
-               .num_pmcs               = 6,
-               .pmc_type               = PPC_PMC_IBM,
-               .oprofile_cpu_type      = "ppc64/power6",
-               .oprofile_type          = PPC_OPROFILE_POWER4,
-               .oprofile_mmcra_sihv    = POWER6_MMCRA_SIHV,
-               .oprofile_mmcra_sipr    = POWER6_MMCRA_SIPR,
-               .oprofile_mmcra_clear   = POWER6_MMCRA_THRM |
-                       POWER6_MMCRA_OTHER,
                .platform               = "power5+",
        },
        {       /* Power6 */
@@ -364,14 +356,6 @@ static struct cpu_spec cpu_specs[] = {
                .cpu_user_features      = COMMON_USER_POWER6,
                .icache_bsize           = 128,
                .dcache_bsize           = 128,
-               .num_pmcs               = 6,
-               .pmc_type               = PPC_PMC_IBM,
-               .oprofile_cpu_type      = "ppc64/power6",
-               .oprofile_type          = PPC_OPROFILE_POWER4,
-               .oprofile_mmcra_sihv    = POWER6_MMCRA_SIHV,
-               .oprofile_mmcra_sipr    = POWER6_MMCRA_SIPR,
-               .oprofile_mmcra_clear   = POWER6_MMCRA_THRM |
-                       POWER6_MMCRA_OTHER,
                .platform               = "power6",
        },
        {       /* Cell Broadband Engine */
@@ -1316,18 +1300,37 @@ static struct cpu_spec cpu_specs[] = {
 #endif /* CONFIG_PPC32 */
 };
 
-struct cpu_spec *identify_cpu(unsigned long offset, unsigned int pvr)
+static struct cpu_spec the_cpu_spec;
+
+struct cpu_spec * __init identify_cpu(unsigned long offset, unsigned int pvr)
 {
        struct cpu_spec *s = cpu_specs;
-       struct cpu_spec **cur = &cur_cpu_spec;
+       struct cpu_spec *t = &the_cpu_spec;
        int i;
 
        s = PTRRELOC(s);
-       cur = PTRRELOC(cur);
+       t = PTRRELOC(t);
 
        for (i = 0; i < ARRAY_SIZE(cpu_specs); i++,s++)
                if ((pvr & s->pvr_mask) == s->pvr_value) {
-                       *cur = cpu_specs + i;
+                       /*
+                        * If we are overriding a previous value derived
+                        * from the real PVR with a new value obtained
+                        * using a logical PVR value, don't modify the
+                        * performance monitor fields.
+                        */
+                       if (t->num_pmcs && !s->num_pmcs) {
+                               t->cpu_name = s->cpu_name;
+                               t->cpu_features = s->cpu_features;
+                               t->cpu_user_features = s->cpu_user_features;
+                               t->icache_bsize = s->icache_bsize;
+                               t->dcache_bsize = s->dcache_bsize;
+                               t->cpu_setup = s->cpu_setup;
+                               t->cpu_restore = s->cpu_restore;
+                               t->platform = s->platform;
+                       } else
+                               *t = *s;
+                       *PTRRELOC(&cur_cpu_spec) = &the_cpu_spec;
 #if defined(CONFIG_PPC64) || defined(CONFIG_BOOKE)
                        /* ppc64 and booke expect identify_cpu to also call 
                         * setup_cpu for that processor. I will consolidate
diff --git a/include/asm-powerpc/cputable.h b/include/asm-powerpc/cputable.h
index c9b8f64..d913f46 100644
--- a/include/asm-powerpc/cputable.h
+++ b/include/asm-powerpc/cputable.h
@@ -57,6 +57,7 @@ enum powerpc_pmc_type {
        PPC_PMC_PA6T = 2,
 };
 
+/* NOTE WELL: Update identify_cpu() if fields are added or removed! */
 struct cpu_spec {
        /* CPU is matched via (PVR & pvr_mask) == pvr_value */
        unsigned int    pvr_mask;
-
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