[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>

2 files changed, 85 insertions, 36 deletions

diff --git a/arch/ppc64/kernel/LparData.c b/arch/ppc64/kernel/LparData.c
index 6ffcf67dd50..76cfd1449d5 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 3f447712e3f..74fc3bc6860 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