[PATCH] ppc64: remove another fixed address constraint

Presently the LparMap, one of the structures the kernel shares with the
legacy iSeries hypervisor has a fixed offset address in head.S.  This patch
changes this so the LparMap is a normally initialized structure, without
fixed address.  This allows us to use macros to compute some of the values
in the structure, which wasn't previously possible because the assembler
always uses signed-% which gets the wrong answers for the computations in
question.

Unfortunately, a gcc bug means that doing this requires another structure
(hvReleaseData) to be initialized in asm instead of C, but on the whole the
result is cleaner than before.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

5 files changed, 109 insertions, 49 deletions

diff --git a/arch/ppc64/kernel/LparData.c b/arch/ppc64/kernel/LparData.c
index 6ffcf67dd507..76cfd1449d52 100644
--- a/arch/ppc64/kernel/LparData.c
+++ b/arch/ppc64/kernel/LparData.c
@@ -33,17 +33,36 @@
  * the hypervisor and Linux.  
  */
 
+/*
+ * WARNING - magic here
+ *
+ * Ok, this is a horrid hack below, but marginally better than the
+ * alternatives.  What we really want is just to initialize
+ * hvReleaseData in C as in the #if 0 section here.  However, gcc
+ * refuses to believe that (u32)&x is a constant expression, so will
+ * not allow the xMsNucDataOffset field to be properly initialized.
+ * So, we declare hvReleaseData in inline asm instead.  We use inline
+ * asm, rather than a .S file, because the assembler won't generate
+ * the necessary relocation for the LparMap either, unless that symbol
+ * is declared in the same source file.  Finally, we put the asm in a
+ * dummy, attribute-used function, instead of at file scope, because
+ * file scope asms don't allow contraints.  We want to use the "i"
+ * constraints to put sizeof() and offsetof() expressions in there,
+ * because including asm/offsets.h in C code then stringifying causes
+ * all manner of warnings.
+ */
+#if 0
 struct HvReleaseData hvReleaseData = {
         .xDesc = 0xc8a5d9c4,    /* "HvRD" ebcdic */
         .xSize = sizeof(struct HvReleaseData),
         .xVpdAreasPtrOffset = offsetof(struct naca_struct, xItVpdAreas),
         .xSlicNacaAddr = &naca,         /* 64-bit Naca address */
-        .xMsNucDataOffset = 0x4800,     /* offset of LparMap within loadarea (see head.S) */
-        .xTagsMode = 1,                 /* tags inactive       */
-        .xAddressSize = 0,              /* 64 bit              */
-        .xNoSharedProcs = 0,            /* shared processors   */
-        .xNoHMT = 0,                    /* HMT allowed         */
-        .xRsvd2 = 6,                    /* TEMP: This allows non-GA driver */
+        .xMsNucDataOffset = (u32)((unsigned long)&xLparMap - KERNELBASE),
+        .xFlags = HVREL_TAGSINACTIVE    /* tags inactive       */
+                                        /* 64 bit              */
+                                        /* shared processors   */
+                                        /* HMT allowed         */
+                  | 6,                  /* TEMP: This allows non-GA driver */
         .xVrmIndex = 4,                 /* We are v5r2m0               */
         .xMinSupportedPlicVrmIndex = 3,         /* v5r1m0 */
         .xMinCompatablePlicVrmIndex = 3,        /* v5r1m0 */
@@ -51,6 +70,63 @@ struct HvReleaseData hvReleaseData = {
                 0xa7, 0x40, 0xf2, 0x4b,
                 0xf4, 0x4b, 0xf6, 0xf4 },
 };
+#endif
+
+
+extern struct HvReleaseData hvReleaseData;
+
+static void __attribute_used__ hvReleaseData_wrapper(void)
+{
+        /* This doesn't appear to need any alignment (even 4 byte) */
+        asm volatile (
+                "       lparMapPhys = xLparMap - %3\n"
+                "       .data\n"
+                "       .globl  hvReleaseData\n"
+                "hvReleaseData:\n"
+                "       .long   0xc8a5d9c4\n"   /* xDesc */
+                                                /* "HvRD" in ebcdic */
+                "       .short  %0\n"           /* xSize */
+                "       .short  %1\n"           /* xVpdAreasPtrOffset */
+                "       .llong  naca\n"         /* xSlicNacaAddr */
+                "       .long   lparMapPhys\n"  /* xMsNucDataOffset */
+                "       .long   0\n"            /* xRsvd1 */
+                "       .short  %2\n"           /* xFlags */
+                "       .short  4\n"    /* xVrmIndex  - v5r2m0 */
+                "       .short  3\n"    /* xMinSupportedPlicVrmIndex - v5r1m0 */
+                "       .short  3\n"    /* xMinCompatablePlicVrmIndex - v5r1m0 */
+                "       .long   0xd38995a4\n"   /* xVrmName */
+                "       .long   0xa740f24b\n"   /*   "Linux 2.4.64" ebcdic */
+                "       .long   0xf44bf6f4\n"
+                "       . = hvReleaseData + %0\n"
+                "       .previous\n"
+                : : "i"(sizeof(hvReleaseData)),
+                "i"(offsetof(struct naca_struct, xItVpdAreas)),
+                "i"(HVREL_TAGSINACTIVE /* tags inactive, 64 bit, */
+                                       /* shared processors, HMT allowed */
+                    | 6), /* TEMP: This allows non-GA drivers */
+                "i"(KERNELBASE)
+                );
+}
+
+struct LparMap __attribute__((aligned (16))) xLparMap = {
+        .xNumberEsids = HvEsidsToMap,
+        .xNumberRanges = HvRangesToMap,
+        .xSegmentTableOffs = STAB0_PAGE,
+
+        .xEsids = {
+                { .xKernelEsid = GET_ESID(KERNELBASE),
+                  .xKernelVsid = KERNEL_VSID(KERNELBASE), },
+                { .xKernelEsid = GET_ESID(VMALLOCBASE),
+                  .xKernelVsid = KERNEL_VSID(VMALLOCBASE), },
+        },
+
+        .xRanges = {
+                { .xPages = HvPagesToMap,
+                  .xOffset = 0,
+                  .xVPN = KERNEL_VSID(KERNELBASE) << (SID_SHIFT - PAGE_SHIFT),
+                },
+        },
+};
 
 extern void system_reset_iSeries(void);
 extern void machine_check_iSeries(void);
diff --git a/arch/ppc64/kernel/head.S b/arch/ppc64/kernel/head.S
index 3f447712e3ff..74fc3bc68604 100644
--- a/arch/ppc64/kernel/head.S
+++ b/arch/ppc64/kernel/head.S
@@ -522,36 +522,9 @@ __end_interrupts:
 #ifdef CONFIG_PPC_ISERIES
         .globl naca
 naca:
-        .llong itVpdAreas
-
-        /*
-         * The iSeries LPAR map is at this fixed address
-         * so that the HvReleaseData structure can address
-         * it with a 32-bit offset.
-         *
-         * The VSID values below are dependent on the
-         * VSID generation algorithm.  See include/asm/mmu_context.h.
-         */
-
-        . = 0x4800
-
-        .llong  2               /* # ESIDs to be mapped by hypervisor    */
-        .llong  1               /* # memory ranges to be mapped by hypervisor */
-        .llong  STAB0_PAGE      /* Page # of segment table within load area     */
-        .llong  0               /* Reserved */
-        .llong  0               /* Reserved */
-        .llong  0               /* Reserved */
-        .llong  0               /* Reserved */
-        .llong  0               /* Reserved */
-        .llong  (KERNELBASE>>SID_SHIFT)
-        .llong  0x408f92c94     /* KERNELBASE VSID */
-        /* We have to list the bolted VMALLOC segment here, too, so that it
-         * will be restored on shared processor switch */
-        .llong  (VMALLOCBASE>>SID_SHIFT)
-        .llong  0xf09b89af5     /* VMALLOCBASE VSID */
-        .llong  8192            /* # pages to map (32 MB) */
-        .llong  0               /* Offset from start of loadarea to start of map */
-        .llong  0x408f92c940000 /* VPN of first page to map */
+        .llong  itVpdAreas
+        .llong  0               /* xRamDisk */
+        .llong  0               /* xRamDiskSize */
 
         . = 0x6100
 
diff --git a/include/asm-ppc64/iSeries/HvReleaseData.h b/include/asm-ppc64/iSeries/HvReleaseData.h
index 01a1f13ea4a0..c8162e5ccb21 100644
--- a/include/asm-ppc64/iSeries/HvReleaseData.h
+++ b/include/asm-ppc64/iSeries/HvReleaseData.h
@@ -39,6 +39,11 @@
  * know that this PLIC does not support running an OS "that old".
  */
 
+#define HVREL_TAGSINACTIVE      0x8000
+#define HVREL_32BIT             0x4000
+#define HVREL_NOSHAREDPROCS     0x2000
+#define HVREL_NOHMT             0x1000
+
 struct HvReleaseData {
         u32     xDesc;          /* Descriptor "HvRD" ebcdic     x00-x03 */
         u16     xSize;          /* Size of this control block   x04-x05 */
@@ -46,11 +51,7 @@ struct HvReleaseData {
         struct  naca_struct     *xSlicNacaAddr; /* Virt addr of SLIC NACA x08-x0F */
         u32     xMsNucDataOffset; /* Offset of Linux Mapping Data x10-x13 */
         u32     xRsvd1;         /* Reserved                     x14-x17 */
-        u16     xTagsMode:1;    /* 0 == tags active, 1 == tags inactive */
-        u16     xAddressSize:1; /* 0 == 64-bit, 1 == 32-bit */
-        u16     xNoSharedProcs:1; /* 0 == shared procs, 1 == no shared */
-        u16     xNoHMT:1;       /* 0 == allow HMT, 1 == no HMT */
-        u16     xRsvd2:12;      /* Reserved                     x18-x19 */
+        u16     xFlags;
         u16     xVrmIndex;      /* VRM Index of OS image        x1A-x1B */
         u16     xMinSupportedPlicVrmIndex; /* Min PLIC level  (soft) x1C-x1D */
         u16     xMinCompatablePlicVrmIndex; /* Min PLIC levelP (hard) x1E-x1F */
diff --git a/include/asm-ppc64/iSeries/LparMap.h b/include/asm-ppc64/iSeries/LparMap.h
index 038e5df7e9f8..5c32e38c1c01 100644
--- a/include/asm-ppc64/iSeries/LparMap.h
+++ b/include/asm-ppc64/iSeries/LparMap.h
@@ -49,19 +49,26 @@
  * entry to map the Esid to the Vsid.
 */
 
+#define HvEsidsToMap    2
+#define HvRangesToMap   1
+
 /* Hypervisor initially maps 32MB of the load area */
 #define HvPagesToMap    8192
 
 struct LparMap {
-        u64     xNumberEsids;   // Number of ESID/VSID pairs (1)
-        u64     xNumberRanges;  // Number of VA ranges to map (1)
-        u64     xSegmentTableOffs; // Page number within load area of seg table (0)
+        u64     xNumberEsids;   // Number of ESID/VSID pairs
+        u64     xNumberRanges;  // Number of VA ranges to map
+        u64     xSegmentTableOffs; // Page number within load area of seg table
         u64     xRsvd[5];
-        u64     xKernelEsid;    // Esid used to map kernel load (0x0C00000000)
-        u64     xKernelVsid;    // Vsid used to map kernel load (0x0C00000000)
-        u64     xPages;         // Number of pages to be mapped (8192)
-        u64     xOffset;        // Offset from start of load area (0)
-        u64     xVPN;           // Virtual Page Number (0x000C000000000000)
+        struct {
+                u64     xKernelEsid;    // Esid used to map kernel load
+                u64     xKernelVsid;    // Vsid used to map kernel load
+        } xEsids[HvEsidsToMap];
+        struct {
+                u64     xPages;         // Number of pages to be mapped
+                u64     xOffset;        // Offset from start of load area
+                u64     xVPN;           // Virtual Page Number
+        } xRanges[HvRangesToMap];
 };
 
 extern struct LparMap           xLparMap;
diff --git a/include/asm-ppc64/mmu.h b/include/asm-ppc64/mmu.h
index 889118036803..70348a851313 100644
--- a/include/asm-ppc64/mmu.h
+++ b/include/asm-ppc64/mmu.h
@@ -338,6 +338,9 @@ static inline unsigned long get_vsid(unsigned long context, unsigned long ea)
                              | (ea >> SID_SHIFT));
 }
 
+#define VSID_SCRAMBLE(pvsid)    (((pvsid) * VSID_MULTIPLIER) % VSID_MODULUS)
+#define KERNEL_VSID(ea)         VSID_SCRAMBLE(GET_ESID(ea))
+
 #endif /* __ASSEMBLY */
 
 #endif /* _PPC64_MMU_H_ */