Rely less on initialized data.

(1) Don't statically initialize HWRPB and PCBB.
(2) Use SwpPal at the end of do_start to install the PCBB and PTBR,
    rather than setting those up in __start in PALmode.
(3) Use -mbuild-constants to prevent the compiler using static data.

1 files changed, 154 insertions, 124 deletions

diff --git a/init.c b/init.c
index f0a0483..25ca743 100644
--- a/init.c
+++ b/init.c
@@ -8,131 +8,44 @@
 #define PAGE_SIZE	(1ul << PAGE_SHIFT)
 #define PAGE_OFFSET	0xfffffc0000000000UL
 
-#if 1
-#define PA(VA)		((unsigned long)(unsigned int)(VA))
-#else
-#define PA(VA)		((VA) - PAGE_OFFSET)
-#endif
-#define VA(PA)		((PA) + PAGE_OFFSET)
+#define VPTPTR		0xfffffffe00000000UL
 
-#define HZ	1024
+#define PA(VA)		((unsigned long)(VA) & 0xfffffffffful)
+#define VA(PA)		((void *)(PA) + PAGE_OFFSET)
 
-struct pcb_struct pal_pcb __attribute__((section(".sbss")));
+#define HZ	1024
 
 struct hwrpb_combine {
   struct hwrpb_struct hwrpb;
   struct percpu_struct processor;
   struct memdesc_struct md;
   struct memclust_struct mc[2];
-} hwrpb __attribute__((section(".data.hwrpb"))) = {
-  /* This is HWRPB\0\0\0.  */
-  .hwrpb.id = 0x4857525042000000,
-
-  .hwrpb.size = sizeof(struct hwrpb_struct),
-  .hwrpb.pagesize = PAGE_SIZE,
-  .hwrpb.ssn = "MILO QEMU",
-
-  /* ??? This should match TARGET_PHYS_ADDR_SPACE_BITS from qemu.  */
-  .hwrpb.pa_bits = 44,
-
-  /* ??? Should we be truethful and say 1 asn, or simply pretend we
-     have ASNs but ignore them?  */
-  .hwrpb.max_asn = 127,
-
-  /* For now, hard-code emulation of sx164.  */
-  .hwrpb.cpuid = PCA56_CPU,
-  .processor.type = PCA56_CPU,
-  .hwrpb.sys_type = ST_DEC_EB164,
-  .hwrpb.sys_variation = 15 << 10,
-  .hwrpb.sys_revision = 0,
-
-  .hwrpb.intr_freq = HZ * 4096,
+};
 
-  /* ??? What the hell should we put here.  Measure like the kernel will?  */
-  .hwrpb.cycle_freq = 400000000,
+extern char stack[PAGE_SIZE] __attribute__((section(".sbss")));
+extern char _end[] __attribute__((visibility("hidden"), nocommon));
 
-  .hwrpb.vptb = 0x200000000UL,
-  .hwrpb.nr_processors = 1,
-  .hwrpb.processor_size = sizeof(struct percpu_struct),
-  .hwrpb.processor_offset = offsetof(struct hwrpb_combine, processor),
+struct pcb_struct pcb __attribute__((section(".sbss")));
 
-  .hwrpb.mddt_offset = offsetof(struct hwrpb_combine, md),
-  .md.numclusters = 2,
-  .mc[0].usage = 2
-};
+static unsigned long page_dir[1024] __attribute__((aligned(PAGE_SIZE)));
 
-unsigned long page_dir[1024] __attribute__((aligned(PAGE_SIZE)));
+/* The HWRPB must be aligned because it is exported at INIT_HWRPB.  */
+struct hwrpb_combine hwrpb __attribute__((aligned(PAGE_SIZE)));
 
-extern char _end[];
-static unsigned long last_alloc = (unsigned long)_end;
+static void *last_alloc;
 
 static void *
 alloc (unsigned long size, unsigned long align)
 {
-  unsigned long p = (last_alloc + align - 1) & ~(align - 1);
+  void *p = (void *)(((unsigned long)last_alloc + align - 1) & ~(align - 1));
   last_alloc = p + size;
-  return memset ((void *)p, 0, size);
+  return memset (p, 0, size);
 }
 
-static unsigned long
-init_cpuid (void)
-{
-  unsigned long implver, amask;
-
-  __asm ("implver %0" : "=r"(implver));
-  __asm ("amask %1,%0" : "=r"(amask) : "r"(-1));
-  amask = ~amask;
-
-  switch (implver)
-    {
-    case 0: /* EV4 */
-      return EV4_CPU;
-
-    case 1: /* EV5 */
-      if ((amask & 0x101) == 0x101)	/* MAX + BWX */
-	return PCA56_CPU;
-      if (amask & 1)			/* BWX */
-	return EV56_CPU;
-      return EV5_CPU;
-
-    case 2: /* EV6 */
-      if (amask & 4)			/* CIX */
-	return EV67_CPU;
-      return EV6_CPU;
-    }
-    return 0;
-}
-
-static void
-hwrpb_update_checksum (void)
-{
-  unsigned long sum = 0, *l;
-  for (l = (unsigned long *) &hwrpb.hwrpb; l < &hwrpb.hwrpb.chksum; ++l)
-    sum += *l;
-  hwrpb.hwrpb.chksum = sum;
-}
-
-static void
-init_hwrpb (unsigned long memsize)
-{
-  unsigned long pal_pages;
-
-  hwrpb.hwrpb.phys_addr = PA((unsigned long)&hwrpb);
-
-  pal_pages = (PA(last_alloc) + PAGE_SIZE - 1) >> PAGE_SHIFT;
-
-  hwrpb.mc[0].numpages = pal_pages;
-  hwrpb.mc[1].start_pfn = pal_pages;
-  hwrpb.mc[1].numpages = (memsize >> PAGE_SHIFT) - pal_pages;
-
-  hwrpb_update_checksum ();
-}
-
-static void
-init_pcb (void)
+static inline unsigned long
+pt_index(unsigned long addr, int level)
 {
-  pal_pcb.ptbr = PA((unsigned long)page_dir);
-  pal_pcb.flags = 1;
+  return (addr >> (PAGE_SHIFT + (10 * level))) & 0x3ff;
 }
 
 static inline unsigned long
@@ -149,7 +62,7 @@ build_pte (void *page)
 static inline void *
 pte_page (unsigned long pte)
 {
-  return (void *)VA(pte >> 32 << PAGE_SHIFT);
+  return VA(pte >> 32 << PAGE_SHIFT);
 }
 
 static void
@@ -158,7 +71,7 @@ set_pte (unsigned long addr, void *page)
   unsigned long *pt = page_dir;
   unsigned long index;
 
-  index = (addr >> (PAGE_SHIFT+20)) % 1024;
+  index = pt_index(addr, 2);
   if (pt[index] != 0)
     pt = pte_page (pt[index]);
   else
@@ -168,7 +81,7 @@ set_pte (unsigned long addr, void *page)
       pt = npt;
     }
 
-  index = (addr >> (PAGE_SHIFT+10)) % 1024;
+  index = pt_index(addr, 1);
   if (pt[index] != 0)
     pt = pte_page (pt[index]);
   else
@@ -178,39 +91,156 @@ set_pte (unsigned long addr, void *page)
       pt = npt;
     }
 
-  index = (addr >> PAGE_SHIFT) % 1024;
+  index = pt_index(addr, 0);
   pt[index] = build_pte (page);
 }
 
 static void
-init_page_table (unsigned long memsize)
+init_page_table(void)
 {
-  unsigned long i, addr, max_addr, page;
+  /* Install the self-reference for the virtual page table base register.  */
+  page_dir[pt_index(VPTPTR, 2)] = build_pte(page_dir);
 
   set_pte ((unsigned long)INIT_HWRPB, &hwrpb);
   
-  /* SRM places the self-map for the VPTBR in the second entry.  */
-  /* MILO places the self-map for the VPTBR in the last entry.  */
-  page_dir[1023] = build_pte (page_dir);
+  /* ??? SRM maps some amount of memory at 0x20000000 for use by programs
+     started from the console prompt.  Including the bootloader.  While
+     we're emulating MILO, don't bother as we jump straight to the kernel
+     loaded into KSEG.  */
+}
+
+static inline unsigned long
+init_cpuid (void)
+{
+  unsigned long implver, amask;
+
+  implver = __builtin_alpha_implver();
+  amask = ~__builtin_alpha_amask(-1);
+
+  switch (implver)
+    {
+    case 0: /* EV4 */
+      return EV4_CPU;
+
+    case 1: /* EV5 */
+      if ((amask & 0x101) == 0x101)	/* MAX + BWX */
+	return PCA56_CPU;
+      if (amask & 1)			/* BWX */
+	return EV56_CPU;
+      return EV5_CPU;
+
+    case 2: /* EV6 */
+      if (amask & 4)			/* CIX */
+	return EV67_CPU;
+      return EV6_CPU;
+    }
+    return 0;
+}
+
+static void
+init_hwrpb (unsigned long memsize)
+{
+  unsigned long pal_pages;
+  
+  hwrpb.hwrpb.phys_addr = PA(&hwrpb);
+
+  /* Yes, the 'HWRPB' magic is in big-endian byte ordering.  */
+  hwrpb.hwrpb.id = ( (long)'H' << 56
+		   | (long)'W' << 48
+		   | (long)'R' << 40
+		   | (long)'P' << 32
+		   | (long)'B' << 24);
+
+  hwrpb.hwrpb.size = sizeof(struct hwrpb_struct);
+
+  /* The inclusion of MILO here tells the Linux kernel that we do
+     not (yet) support any of the extended console support routines
+     that are in SRM.  */
+  ((int *)hwrpb.hwrpb.ssn)[0] = ( 'M' << 0
+				| 'I' << 8
+				| 'L' << 16
+				| 'O' << 24);
+  ((int *)hwrpb.hwrpb.ssn)[1] = ( ' ' << 0
+				| 'Q' << 8
+				| 'E' << 16
+				| 'M' << 24);
+  ((int *)hwrpb.hwrpb.ssn)[2] = ( 'U' << 0);
+
+  /* For now, hard-code emulation of sx164.  */
+  hwrpb.hwrpb.cpuid = PCA56_CPU;
+  hwrpb.hwrpb.pagesize = PAGE_SIZE;
+  hwrpb.hwrpb.pa_bits = 40;
+  hwrpb.hwrpb.max_asn = 127;
+  hwrpb.hwrpb.sys_type = ST_DEC_EB164;
+  hwrpb.hwrpb.sys_variation = 15 << 10;
+  hwrpb.hwrpb.sys_revision = 0;
+  hwrpb.processor.type = PCA56_CPU;
+
+  hwrpb.hwrpb.intr_freq = HZ * 4096;
+
+  /* ??? What the hell should we put here.  Measure like the kernel will?  */
+  hwrpb.hwrpb.cycle_freq = 400000000;
+
+  hwrpb.hwrpb.vptb = VPTPTR;
+
+  hwrpb.hwrpb.nr_processors = 1;
+  hwrpb.hwrpb.processor_size = sizeof(struct percpu_struct);
+  hwrpb.hwrpb.processor_offset = offsetof(struct hwrpb_combine, processor);
+
+  hwrpb.hwrpb.mddt_offset = offsetof(struct hwrpb_combine, md);
+  hwrpb.md.numclusters = 2;
+
+  pal_pages = (PA(last_alloc) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+  hwrpb.mc[0].numpages = pal_pages;
+  hwrpb.mc[0].usage = 1;
+  hwrpb.mc[1].start_pfn = pal_pages;
+  hwrpb.mc[1].numpages = (memsize >> PAGE_SHIFT) - pal_pages;
 
-  /* Write the SRM vptptr.  */
   {
-    register unsigned long a0 __asm__("$16") = 0xfffffffe00000000UL;
-    __asm ("call_pal 0x2d" : : "r"(a0));
+    unsigned long sum = 0, *l;
+    for (l = (unsigned long *) &hwrpb.hwrpb; l < &hwrpb.hwrpb.chksum; ++l)
+      sum += *l;
+    hwrpb.hwrpb.chksum = sum;
   }
 }
 
+static void
+init_pcb (void)
+{
+  pcb.ksp = (unsigned long)stack + sizeof(stack);
+  pcb.ptbr = PA(page_dir);
+  pcb.flags = 1; /* FEN */
+}
+
+void
+do_hello(void)
+{
+  uart_puts(COM1, "Hello, World!\n");
+  asm ("halt");
+  __builtin_unreachable ();
+}
+
 void
 do_start(unsigned long memsize, void (*kernel_entry)(void))
 {
-  init_page_table (memsize);
-  init_hwrpb (memsize);
-  init_pcb ();
+  last_alloc = _end;
 
-  uart_init ();
-  uart_puts (COM1, "Hello, World!\n");
+  init_page_table();
+  init_hwrpb(memsize);
+  init_pcb();
+  uart_init();
 
-  if (kernel_entry)
-    kernel_entry();
-  asm ("halt");
+  {
+    register int variant __asm__("$16") = 2;	/* OSF/1 PALcode */
+    register void (*pc)(void) __asm__("$17");
+    register unsigned long pa_pcb __asm__("$18");
+    register unsigned long vptptr __asm__("$19");
+
+    pc = (kernel_entry ? kernel_entry : do_hello);
+    pa_pcb = PA(&pcb);
+    vptptr = VPTPTR;
+    asm("call_pal 0x0a" : : "r"(variant), "r"(pc), "r"(pa_pcb), "r"(vptptr));
+  }
+  __builtin_unreachable ();
 }