[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>

1 files changed, 82 insertions, 6 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);